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Keita MATSUNO
International Institute for Zoonosis Control　Division of Risk Analysis and Management
Associate Professor
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Last Updated :2024/05/09

Researcher Profile and Settings

Affiliation

  • International Institute for Zoonosis Control　Division of Risk Analysis and Management

Job Title

  • Associate Professor

Degree

  • 博士（獣医学）（北海道大学）

Research funding number

  • 40753306

J-Global ID

Educational Organization

Academic & Professional Experience

  • 2023/10 - Today Hokkaido University One Health Research Center Associate Professor
  • 2022/12 - Today Hokkaido University International Institute for Zoonosis Control Associate Professor

Research Activities

Published Papers

  • Mohamed Abdallah Mohamed Moustafa, Wessam M A Mohamed, Elisha Chatanga, Doaa Nagib, Keita Matsuno, Alexander W Gofton, Stephen C Barker, Nariaki Nonaka, Ryo Nakao
    Scientific reports 14 (1) 9961 - 9961 2024/04/30 
    Ticks have a profound impact on public health. Haemaphysalis is one of the most widespread genera in Asia, including Japan. The taxonomy and genetic differentiation of Haemaphysalis spp. is challenging. For instance, previous studies struggled to distinguish Haemaphysalis japonica and Haemaphysalis megaspinosa due to the dearth of nucleotide sequence polymorphisms in widely used barcoding genes. The classification of H. japonica japonica and its related sub-species Haemaphysalis japonica douglasi or Haemaphysalis jezoensis is also confused due to their high morphological similarity and a lack of molecular data that support the current classification. We used mitogenomes and microbiomes of H. japonica and H. megaspinosa to gain deeper insights into the phylogenetic relationships and genetic divergence between two species. Phylogenetic analyses of concatenated nucleotide sequences of protein-coding genes and ribosomal DNA genes distinguished H. japonica and H. megaspinosa as monophyletic clades, with further subdivision within the H. japonica clade. The 16S rRNA and NAD5 genes were valuable markers for distinguishing H. japonica and H. megaspinosa. Population genetic structure analyses indicated that genetic variation within populations accounted for a large proportion of the total variation compared to variation between populations. Microbiome analyses revealed differences in alpha and beta diversity between H. japonica and H. megaspinosa: H. japonica had the higher diversity. Coxiella sp., a likely endosymbiont, was found in both Haemaphysalis species. The abundance profiles of likely endosymbionts, pathogens, and commensals differed between H. japonica and H. megaspinosa: H. megaspinosa was more diverse.
  • Takuma Ariizumi, Koshiro Tabata, Yukari Itakura, Hiroko Kobayashi, William W Hall, Michihito Sasaki, Hirofumi Sawa, Keita Matsuno, Yasuko Orba
    PLoS pathogens 20 (3) e1012101  2024/03 
    Emerging and reemerging tick-borne virus infections caused by orthonairoviruses (family Nairoviridae), which are genetically distinct from Crimean-Congo hemorrhagic fever virus, have been recently reported in East Asia. Here, we have established a mouse infection model using type-I/II interferon receptor-knockout mice (AG129 mice) both for a better understanding of the pathogenesis of these infections and validation of antiviral agents using Yezo virus (YEZV), a novel orthonairovirus causing febrile illnesses associated with tick bites in Japan and China. YEZV-inoculated AG129 mice developed hepatitis with body weight loss and died by 6 days post infection. Blood biochemistry tests showed elevated liver enzyme levels, similar to YEZV-infected human patients. AG129 mice treated with favipiravir survived lethal YEZV infection, demonstrating the anti-YEZV effect of this drug. The present mouse model will help us better understand the pathogenicity of the emerging tick-borne orthonairoviruses and the development of specific antiviral agents for their treatment.
  • Tomokazu Tamura, Keita Mizuma, Hesham Nasser, Sayaka Deguchi, Miguel Padilla-Blanco, Yoshitaka Oda, Keiya Uriu, Jarel E M Tolentino, Shuhei Tsujino, Rigel Suzuki, Isshu Kojima, Naganori Nao, Ryo Shimizu, Lei Wang, Masumi Tsuda, Michael Jonathan, Yusuke Kosugi, Ziyi Guo, Alfredo A Hinay Jr, Olivia Putri, Yoonjin Kim, Yuri L Tanaka, Hiroyuki Asakura, Mami Nagashima, Kenji Sadamasu, Kazuhisa Yoshimura, Akatsuki Saito, Jumpei Ito, Takashi Irie, Shinya Tanaka, Jiri Zahradnik, Terumasa Ikeda, Kazuo Takayama, Keita Matsuno, Takasuke Fukuhara, Kei Sato
    Cell host & microbe 32 (2) 170 - 180 2024/02/14 
    In late 2023, several SARS-CoV-2 XBB descendants, notably EG.5.1, were predominant worldwide. However, a distinct SARS-CoV-2 lineage, the BA.2.86 variant, also emerged. BA.2.86 is phylogenetically distinct from other Omicron sublineages, accumulating over 30 amino acid mutations in its spike protein. Here, we examined the virological characteristics of the BA.2.86 variant. Our epidemic dynamics modeling suggested that the relative reproduction number of BA.2.86 is significantly higher than that of EG.5.1. Additionally, four clinically available antivirals were effective against BA.2.86. Although the fusogenicity of BA.2.86 spike is similar to that of the parental BA.2 spike, the intrinsic pathogenicity of BA.2.86 in hamsters was significantly lower than that of BA.2. Since the growth kinetics of BA.2.86 are significantly lower than those of BA.2 both in vitro and in vivo, the attenuated pathogenicity of BA.2.86 is likely due to its decreased replication capacity. These findings uncover the features of BA.2.86, providing insights for control and treatment.
  • Keiichi Taniguchi, Takeshi Noshi, Shinya Omoto, Akihiko Sato, Takao Shishido, Keita Matsuno, Masatoshi Okamatsu, Scott Krauss, Richard J Webby, Yoshihiro Sakoda, Hiroshi Kida
    Archives of virology 169 (2) 29 - 29 2024/01/12 
    Genetic reassortment of avian, swine, and human influenza A viruses (IAVs) poses potential pandemic risks. Surveillance is important for influenza pandemic preparedness, but the susceptibility of zoonotic IAVs to the cap-dependent endonuclease inhibitor baloxavir acid (BXA) has not been thoroughly researched. Although an amino acid substitution at position 38 in the polymerase acidic protein (PA/I38) in seasonal IAVs reduces BXA susceptibility, PA polymorphisms at position 38 are rarely seen in zoonotic IAVs. Here, we examined the impact of PA/I38 substitutions on the BXA susceptibility of recombinant A(H5N1) viruses. PA mutants that harbored I38T, F, and M were 48.2-, 24.0-, and 15.5-fold less susceptible, respectively, to BXA than wild-type A(H5N1) but were susceptible to the neuraminidase inhibitor oseltamivir acid and the RNA polymerase inhibitor favipiravir. PA mutants exhibited significantly impaired replicative fitness in Madin-Darby canine kidney cells at 24 h postinfection. In addition, in order to investigate new genetic markers for BXA susceptibility, we screened geographically and temporally distinct IAVs isolated worldwide from birds and pigs. The results showed that BXA exhibited antiviral activity against avian and swine viruses with similar levels to seasonal isolates. All viruses tested in the study lacked the PA/I38 substitution and were susceptible to BXA. Isolates harboring amino acid polymorphisms at positions 20, 24, and 37, which have been implicated in the binding of BXA to the PA endonuclease domain, were also susceptible to BXA. These results suggest that monitoring of the PA/I38 substitution in animal-derived influenza viruses is important for preparedness against zoonotic influenza virus outbreaks.
  • Michihito Sasaki, Tatsuki Sugi, Shun Iida, Yuichiro Hirata, Shinji Kusakabe, Kei Konishi, Yukari Itakura, Koshiro Tabata, Mai Kishimoto, Hiroko Kobayashi, Takuma Ariizumi, Kittiya Intaruck, Haruaki Nobori, Shinsuke Toba, Akihiko Sato, Keita Matsuno, Junya Yamagishi, Tadaki Suzuki, William W Hall, Yasuko Orba, Hirofumi Sawa
    EBioMedicine 99 104950 - 104950 2023/12/29 
    BACKGROUND: Pulmonary infection with SARS-CoV-2 stimulates host immune responses and can also result in the progression of dysregulated and critical inflammation. Throughout the pandemic, the management and treatment of COVID-19 has been continuously updated with a range of antiviral drugs and immunomodulators. Monotherapy with oral antivirals has proven to be effective in the treatment of COVID-19. However, treatment should be initiated in the early stages of infection to ensure beneficial therapeutic outcomes, and there is still room for further consideration on therapeutic strategies using antivirals. METHODS: We studied the therapeutic effects of monotherapy with the oral antiviral ensitrelvir or the anti-inflammatory corticosteroid methylprednisolone and combination therapy with ensitrelvir and methylprednisolone in a delayed dosing model of hamsters infected with SARS-CoV-2. FINDINGS: Combination therapy with ensitrelvir and methylprednisolone improved respiratory conditions and reduced the development of pneumonia in hamsters even when the treatment was started after 2 days post-infection. The combination therapy led to a differential histological and transcriptomic pattern in comparison to either of the monotherapies, with reduced lung damage and down-regulation of expression of genes involved in the inflammatory response. Furthermore, we found that the combination treatment is effective in case of infection with either the highly pathogenic delta or circulating omicron variants. INTERPRETATION: Our results demonstrate the advantage of combination therapy with antiviral and corticosteroid drugs in COVID-19 treatment from the perspective of lung pathology and host inflammatory responses. FUNDING: Funding bodies are described in the Acknowledgments section.
  • Shigeru Fujita, Yusuke Kosugi, Izumi Kimura, Kenzo Tokunaga, Jumpei Ito, Kei Sato, Keita Matsuno, Naganori Nao, Hirofumi Sawa, Shinya Tanaka, Masumi Tsuda, Lei Wang, Yoshikata Oda, Zannatul Ferdous, Kenji Shishido, Takasuke Fukuhara, Tomokazu Tamura, Rigel Suzuki, Saori Suzuki, Hayato Ito, Yu Kaku, Naoko Misawa, Arnon Plianchaisuk, Ziyi Guo, Alfredo A. Hinay, Keiya Uriu, Jarel Elgin M. Tolentino, Luo Chen, Lin Pan, Mai Suganami, Mika Chiba, Ryo Yoshimura, Kyoko Yasuda, Keiko Iida, Naomi Ohsumi, Adam P. Strange, Shiho Tanaka, Kazuhisa Yoshimura, Kenji Sadamasu, Mami Nagashima, Hiroyuki Asakura, Isao Yoshida, So Nakagawa, Akifumi Takaori-Kondo, Kayoko Nagata, Ryosuke Nomura, Yoshihito Horisawa, Yusuke Tashiro, Yugo Kawai, Kazuo Takayama, Rina Hashimoto, Sayaka Deguchi, Yukio Watanabe, Ayaka Sakamoto, Naoko Yasuhara, Takao Hashiguchi, Tateki Suzuki, Kanako Kimura, Jiei Sasaki, Yukari Nakajima, Hisano Yajima, Takashi Irie, Ryoko Kawabata, Kaori Tabata, Terumasa Ikeda, Hesham Nasser, Ryo Shimizu, M. S. T. Monira Begum, Michael Jonathan, Yuka Mugita, Otowa Takahashi, Kimiko Ichihara, Chihiro Motozono, Takamasa Ueno, Mako Toyoda, Akatsuki Saito, Maya Shofa, Yuki Shibatani, Tomoko Nishiuchi, Kotaro Shirakawa
    Journal of Virology 97 (10) 0022-538X 2023/10/31 
    ABSTRACT Differences in host angiotensin converting enzyme 2 (ACE2) genes may affect the host range of SARS-CoV-2-related coronaviruses (SC2r-CoVs) and further determine the tropism of host ACE2 for the infection receptor. However, the factor(s) responsible for determining the host tropism of SC2r-CoVs, which may in part be determined by the tropism of host ACE2 usage, remains unclear. Here, we use the pseudoviruses with the spike proteins of two Laotian SC2r-CoVs, BANAL-20-236 and BANAL-20-52, and the cells expressing ACE2 proteins of eight different Rhinolophus bat species to show that these two spikes have different tropisms for Rhinolophus bat ACE2. Through structural analysis and cell culture experiments, we demonstrate that this tropism is determined by residue 493 of the spike and residues 31 and 35 of ACE2. Our results suggest that SC2r-CoVs exhibit differential ACE2 tropism, which may be driven by adaptation to different Rhinolophus bat ACE2 proteins. IMPORTANCE The efficiency of infection receptor use is the first step in determining the species tropism of viruses. After the coronavirus disease 2019 pandemic, a number of SARS-CoV-2-related coronaviruses (SC2r-CoVs) were identified in Rhinolophus bats, and some of them can use human angiotensin converting enzyme 2 (ACE2) for the infection receptor without acquiring additional mutations. This means that the potential of certain SC2r-CoVs to cause spillover from bats to humans is "off-the-shelf." However, both SC2r-CoVs and Rhinolophus bat species are highly diversified, and the host tropism of SC2r-CoVs remains unclear. Here, we focus on two Laotian SC2r-CoVs, BANAL-20-236 and BANAL-20-52, and determine how the tropism of SC2r-CoVs to Rhinolophus bat ACE2 is determined at the amino acid resolution level.
  • Yasuko Orba, Yusuf Eshimutu Abu, Herman M Chambaro, Tapiwa Lundu, Walter Muleya, Yuki Eshita, Yongjin Qiu, Hayato Harima, Masahiro Kajihara, Akina Mori-Kajihara, Keita Matsuno, Michihito Sasaki, William W Hall, Bernard M Hang'ombe, Hirofumi Sawa
    Scientific reports 13 (1) 18165 - 18165 2023/10/24 
    Mosquitoes interact with various organisms in the environment, and female mosquitoes in particular serve as vectors that directly transmit a number of microorganisms to humans and animals by blood-sucking. Comprehensive analysis of mosquito-borne viruses has led to the understanding of the existence of diverse viral species and to the identification of zoonotic arboviruses responsible for significant outbreaks and epidemics. In the present study on mosquito-borne bunyaviruses we employed a broad-spectrum RT-PCR approach and identified eighteen different additional species in the Phenuiviridae family and also a number of related but unclassified bunyaviruses in mosquitoes collected in Zambia. The entire RNA genome segments of the newly identified viruses were further analyzed by RNA sequencing with a ribonuclease R (RNase R) treatment to reduce host-derived RNAs and enrich viral RNAs, taking advantage of the dsRNA panhandle structure of the bunyavirus genome. All three or four genome segments were identified in eight bunyavirus species. Furthermore, L segments of three different novel viruses related to the Leishbunyaviridae were found in mosquitoes together with genes from the suspected host, the Crithidia parasite. In summary, our virus detection approach using a combination of broad-spectrum RT-PCR and RNA sequencing analysis with a simple virus enrichment method allowed the discovery of novel bunyaviruses. The diversity of bunyaviruses is still expanding and studies on this will allow a better understanding of the ecology of hematophagous mosquitoes.
  • Kentaro Uemura, Haruaki Nobori, Akihiko Sato, Shinsuke Toba, Shinji Kusakabe, Michihito Sasaki, Koshiro Tabata, Keita Matsuno, Naoyoshi Maeda, Shiori Ito, Mayu Tanaka, Yuki Anraku, Shunsuke Kita, Mayumi Ishii, Kayoko Kanamitsu, Yasuko Orba, Yoshiharu Matsuura, William W Hall, Hirofumi Sawa, Hiroshi Kida, Akira Matsuda, Katsumi Maenaka
    Proceedings of the National Academy of Sciences of the United States of America 120 (42) e2304139120  2023/10/17 
    Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections are causing significant morbidity and mortality worldwide. Furthermore, over 1 million cases of newly emerging or re-emerging viral infections, specifically dengue virus (DENV), are known to occur annually. Because no virus-specific and fully effective treatments against these or many other viruses have been approved, there is an urgent need for novel, effective therapeutic agents. Here, we identified 2-thiouridine (s2U) as a broad-spectrum antiviral ribonucleoside analogue that exhibited antiviral activity against several positive-sense single-stranded RNA (ssRNA+) viruses, such as DENV, SARS-CoV-2, and its variants of concern, including the currently circulating Omicron subvariants. s2U inhibits RNA synthesis catalyzed by viral RNA-dependent RNA polymerase, thereby reducing viral RNA replication, which improved the survival rate of mice infected with DENV2 or SARS-CoV-2 in our animal models. Our findings demonstrate that s2U is a potential broad-spectrum antiviral agent not only against DENV and SARS-CoV-2 but other ssRNA+ viruses.
  • Shohei Ogata, Rika Umemiya-Shirafuji, Kodai Kusakisako, Keita Kakisaka, Elisha Chatanga, Naoki Hayashi, Yurie Taya, Yuma Ohari, Gita Sadaula Pandey, Abdelbaset Eweda Abdelbaset, Yongjin Qiu, Keita Matsuno, Nariaki Nonaka, Ryo Nakao
    Scientific Reports 13 (1) 13265 - 13265 2023/08/15 
    Abstract Many arthropods harbour bacterial symbionts, which are maintained by vertical and/or horizontal transmission. Spiroplasma is one of the most well-known symbionts of ticks and other arthropods. It is still unclear how Spiroplasma infections have spread in tick populations despite its high prevalence in some tick species. In this study, Ixodes ovatus, which has been reported to harbour Spiroplasma ixodetis at high frequencies, was examined for its vertical transmission potential under experimental conditions. Next, two isolates of tick-derived Spiroplasma, S. ixodetis and Spiroplasma mirum, were experimentally inoculated into Spiroplasma-free Haemaphysalis longicornis colonies and the presence of Spiroplasma in their eggs and larvae was tested. Our experimental data confirmed that S. ixodetis was transmitted to eggs and larvae in a vertical manner in the original host I. ovatus. In the second experiment, there was no significant difference in engorged weight, egg weight, and hatching rate between Spiroplasma-inoculated and control H. longicornis groups. This suggested that Spiroplasma infection does not affect tick reproduction. Spiroplasma DNA was only detected in the eggs and larvae derived from some individuals of S. ixodetis-inoculated groups. This has demonstrated the potential of horizontal transmission between different tick species. These findings may help understand the transmission dynamics of Spiroplasma in nature and its adaptation mechanism to host arthropod species.
  • Tomokazu Tamura, Daichi Yamasoba, Yoshitaka Oda, Jumpei Ito, Tomoko Kamasaki, Naganori Nao, Rina Hashimoto, Yoichiro Fujioka, Rigel Suzuki, Lei Wang, Hayato Ito, Yukie Kashima, Izumi Kimura, Mai Kishimoto, Masumi Tsuda, Hirofumi Sawa, Kumiko Yoshimatsu, Yuki Yamamoto, Tetsuharu Nagamoto, Jun Kanamune, Yutaka Suzuki, Yusuke Ohba, Isao Yokota, Keita Matsuno, Kazuo Takayama, Shinya Tanaka, Kei Sato, Takasuke Fukuhara
    Communications biology 6 (1) 772 - 772 2023/07/24 
    The unremitting emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants necessitates ongoing control measures. Given its rapid spread, the new Omicron subvariant BA.5 requires urgent characterization. Here, we comprehensively analyzed BA.5 with the other Omicron variants BA.1, BA.2, and ancestral B.1.1. Although in vitro growth kinetics of BA.5 was comparable among the Omicron subvariants, BA.5 was much more fusogenic than BA.1 and BA.2. Airway-on-a-chip analysis showed that, among Omicron subvariants, BA.5 had enhanced ability to disrupt the respiratory epithelial and endothelial barriers. Furthermore, in our hamster model, in vivo pathogenicity of BA.5 was slightly higher than that of the other Omicron variants and less than that of ancestral B.1.1. Notably, BA.5 gains efficient virus spread compared with BA.1 and BA.2, leading to prompt immune responses. Our findings suggest that BA.5 has low pathogenicity compared with the ancestral strain but enhanced virus spread /inflammation compared with earlier Omicron subvariants.
  • Shigeru Fujita, Keiya Uriu, Lin Pan, Naganori Nao, Koshiro Tabata, Mai Kishimoto, Yukari Itakura, Hirofumi Sawa, Izumi Kida, Tomokazu Tamura, Takasuke Fukuhara, Jumpei Ito, Keita Matsuno, Kei Sato
    The Journal of infectious diseases 2023/06/27 
    The emergence of SARS-CoV-2 Omicron variants has led to concerns that ancestral SARS-CoV-2-based vaccines may not be effective against newly emerging Omicron subvariants. The concept of "imprinted immunity" suggests that individuals vaccinated with ancestral virus-based vaccines may not develop effective immunity against newly emerging Omicron subvariants, such as BQ.1.1 and XBB.1. Here, we investigated this possibility using hamsters. While natural infection induced effective antiviral immunity, breakthrough infections in hamsters with BQ.1.1 and XBB.1 Omicron subvariants after receiving the 3-dose mRNA-LNP vaccine resulted in only faintly induced humoral immunity, supporting the possibility of imprinted immunity.
  • Tomokazu Tamura, Jumpei Ito, Keiya Uriu, Jiri Zahradnik, Izumi Kida, Yuki Anraku, Hesham Nasser, Maya Shofa, Yoshitaka Oda, Spyros Lytras, Naganori Nao, Yukari Itakura, Sayaka Deguchi, Rigel Suzuki, Lei Wang, Mst Monira Begum, Shunsuke Kita, Hisano Yajima, Jiei Sasaki, Kaori Sasaki-Tabata, Ryo Shimizu, Masumi Tsuda, Yusuke Kosugi, Shigeru Fujita, Lin Pan, Daniel Sauter, Kumiko Yoshimatsu, Saori Suzuki, Hiroyuki Asakura, Mami Nagashima, Kenji Sadamasu, Kazuhisa Yoshimura, Yuki Yamamoto, Tetsuharu Nagamoto, Gideon Schreiber, Katsumi Maenaka, Takao Hashiguchi, Terumasa Ikeda, Takasuke Fukuhara, Akatsuki Saito, Shinya Tanaka, Keita Matsuno, Kazuo Takayama, Kei Sato
    Nature communications 14 (1) 2800 - 2800 2023/05/16 
    In late 2022, SARS-CoV-2 Omicron subvariants have become highly diversified, and XBB is spreading rapidly around the world. Our phylogenetic analyses suggested that XBB emerged through the recombination of two cocirculating BA.2 lineages, BJ.1 and BM.1.1.1 (a progeny of BA.2.75), during the summer of 2022. XBB.1 is the variant most profoundly resistant to BA.2/5 breakthrough infection sera to date and is more fusogenic than BA.2.75. The recombination breakpoint is located in the receptor-binding domain of spike, and each region of the recombinant spike confers immune evasion and increases fusogenicity. We further provide the structural basis for the interaction between XBB.1 spike and human ACE2. Finally, the intrinsic pathogenicity of XBB.1 in male hamsters is comparable to or even lower than that of BA.2.75. Our multiscale investigation provides evidence suggesting that XBB is the first observed SARS-CoV-2 variant to increase its fitness through recombination rather than substitutions.
  • Jumpei Ito, Rigel Suzuki, Keiya Uriu, Yukari Itakura, Jiri Zahradnik, Kanako Terakado Kimura, Sayaka Deguchi, Lei Wang, Spyros Lytras, Tomokazu Tamura, Izumi Kida, Hesham Nasser, Maya Shofa, Mst Monira Begum, Masumi Tsuda, Yoshitaka Oda, Tateki Suzuki, Jiei Sasaki, Kaori Sasaki-Tabata, Shigeru Fujita, Kumiko Yoshimatsu, Hayato Ito, Naganori Nao, Hiroyuki Asakura, Mami Nagashima, Kenji Sadamasu, Kazuhisa Yoshimura, Yuki Yamamoto, Tetsuharu Nagamoto, Jin Kuramochi, Gideon Schreiber, Akatsuki Saito, Keita Matsuno, Kazuo Takayama, Takao Hashiguchi, Shinya Tanaka, Takasuke Fukuhara, Terumasa Ikeda, Kei Sato
    Nature communications 14 (1) 2671 - 2671 2023/05/11 
    In late 2022, various Omicron subvariants emerged and cocirculated worldwide. These variants convergently acquired amino acid substitutions at critical residues in the spike protein, including residues R346, K444, L452, N460, and F486. Here, we characterize the convergent evolution of Omicron subvariants and the properties of one recent lineage of concern, BQ.1.1. Our phylogenetic analysis suggests that these five substitutions are recurrently acquired, particularly in younger Omicron lineages. Epidemic dynamics modelling suggests that the five substitutions increase viral fitness, and a large proportion of the fitness variation within Omicron lineages can be explained by these substitutions. Compared to BA.5, BQ.1.1 evades breakthrough BA.2 and BA.5 infection sera more efficiently, as demonstrated by neutralization assays. The pathogenicity of BQ.1.1 in hamsters is lower than that of BA.5. Our multiscale investigations illuminate the evolutionary rules governing the convergent evolution for known Omicron lineages as of 2022.
  • Kazuya Takehana, Keita Matsuno
    The Journal of veterinary medical science 85 (4) 459 - 462 2023/03/30 
    Elephant endotheliotropic herpesvirus (EEHV) causes a fatal hemorrhagic disease and is a significant cause of mortality in juvenile Asian elephants. A loop-mediated isothermal amplification (LAMP) method was developed to rapidly diagnose EEHV viremia. However, extracting DNA from whole blood samples to perform LAMP hampers diagnosis in a field setting. Here, we established the Direct-LAMP method, using heparinized plasma without extracting the DNA to speed up and simplify the test. EEHV-positive specimens were tested using the Direct-LAMP. The detection limit was calculated to be 101.3 copies/μL using the mimetic samples, which was almost identical to the value determined in LAMP in which DNA was extracted. Hence, the Direct-LAMP provided a more rapid diagnosis to save, which could prevent elephant deaths.
  • 渡り鳥によるYezoウイルス保有マダニの運搬
    西野 綾乃, 立本 完吾, 井上 雄介, 石嶋 慧多, 黒田 雄大, Mendoza Milagros, 原田 倫子, 朴 ウンシル, 下田 宙, 高野 愛, 仲村 昇, 森本 元, 松野 啓太, 前田 健
    衛生動物 日本衛生動物学会 74 (Suppl.) 61 - 61 0424-7086 2023/03
  • Yuta Tsukamoto, Takahiro Hiono, Shintaro Yamada, Keita Matsuno, Aileen Faist, Tobias Claff, Jianyu Hou, Vigneshwaran Namasivayam, Anja Vom Hemdt, Satoko Sugimoto, Jin Ying Ng, Maria H Christensen, Yonas M Tesfamariam, Steven Wolter, Stefan Juranek, Thomas Zillinger, Stefan Bauer, Takatsugu Hirokawa, Florian I Schmidt, Georg Kochs, Masayuki Shimojima, Yi-Shuian Huang, Andreas Pichlmair, Beate M Kümmerer, Yoshihiro Sakoda, Martin Schlee, Linda Brunotte, Christa E Müller, Manabu Igarashi, Hiroki Kato
    Science (New York, N.Y.) 379 (6632) 586 - 591 2023/02/10 
    Orthomyxo- and bunyaviruses steal the 5' cap portion of host RNAs to prime their own transcription in a process called "cap snatching." We report that RNA modification of the cap portion by host 2'-O-ribose methyltransferase 1 (MTr1) is essential for the initiation of influenza A and B virus replication, but not for other cap-snatching viruses. We identified with in silico compound screening and functional analysis a derivative of a natural product from Streptomyces, called trifluoromethyl-tubercidin (TFMT), that inhibits MTr1 through interaction at its S-adenosyl-l-methionine binding pocket to restrict influenza virus replication. Mechanistically, TFMT impairs the association of host cap RNAs with the viral polymerase basic protein 2 subunit in human lung explants and in vivo in mice. TFMT acts synergistically with approved anti-influenza drugs.
  • 国内のネコ・イヌにおける重症熱性血小板減少症候群の発生状況
    石嶋 慧多, 平良 雅克, 松鵜 彩, 朴 ウンシル, 立本 完吾, 木村 昌伸, 藤田 修, 前田 健, 森川 茂, 岡林 環樹, 早坂 大輔, 井上 真吾, 高松 由基, 桃井 康行, 水谷 哲也, 松野 啓太, 山岡 弘二
    病原微生物検出情報月報 国立感染症研究所 44 (2) 31 - 32 0915-5813 2023/02
  • Kien Trung Le, Lam Thanh Nguyen, Loc Tan Huynh, Duc-Huy Chu, Long Van Nguyen, Tien Ngoc Nguyen, Tien Ngoc Tien, Keita Matsuno, Masatoshi Okamatsu, Takahiro Hiono, Norikazu Isoda, Yoshihiro Sakoda
    Microorganisms 11 (2) 2023/01/18 
    The H9 and H6 subtypes of low pathogenicity avian influenza viruses (LPAIVs) cause substantial economic losses in poultry worldwide, including Vietnam. Herein, we characterized Vietnamese H9 and H6 LPAIVs to facilitate the control of avian influenza. The space-time representative viruses of each subtype were selected based on active surveillance from 2014 to 2018 in Vietnam. Phylogenetic analysis using hemagglutinin genes revealed that 54 H9 and 48 H6 Vietnamese LPAIVs were classified into the sublineages Y280/BJ94 and Group II, respectively. Gene constellation analysis indicated that 6 and 19 genotypes of the H9 and H6 subtypes, respectively, belonged to the representative viruses. The Vietnamese viruses are genetically related to the previous isolates and those in neighboring countries, indicating their circulation in poultry after being introduced into Vietnam. The antigenicity of these subtypes was different from that of viruses isolated from wild birds. Antigenicity was more conserved in the H9 viruses than in the H6 viruses. Furthermore, a representative H9 LPAIV exhibited systemic replication in chickens, which was enhanced by coinfection with avian pathogenic Escherichia coli O2. Although H9 and H6 were classified as LPAIVs, their characterization indicated that their silent spread might significantly affect the poultry industry.
  • Takahiro Hiono, Daiki Kobayashi, Atsushi Kobayashi, Tamami Suzuki, Yuki Satake, Rio Harada, Keita Matsuno, Mariko Sashika, Hinako Ban, Maya Kobayashi, Keisuke Aoshima, Fumihito Takaya, Hiroko Fujita, Norikazu Isoda, Takashi Kimura, Yoshihiro Sakoda
    Virology 578 35 - 44 2023/01 [Refereed][Not invited]
     
    In winter/spring 2021-2022, high pathogenicity avian influenza viruses (HPAIVs) that are genetically closely related to each other were detected worldwide. In a public garden in Sapporo, Hokkaido, Japan, a crow die-off by HPAIV infection occurred from March 29 to May 18, 2022. During the event, H5N1 HPAIVs were isolated from an Ezo red fox (Vulpes vulpes schrencki) and a tanuki (Nyctereutes procyonoides albus) found in the same garden. The fox showed viral meningoencephalitis and moderate virus replication in the upper respiratory tract, whereas the tanuki showed viral conjunctivitis and secondary bacterial infection in the eyes accompanied with visceral larva migrans. Viruses isolated from the fox and the tanuki were genetically closely related to those isolated from crows in the same garden. Various α2-3 sialosides were found in the respiratory tracts of these canid mammals, consistent with HPAIV infections in these animals. This study highlighted the importance of monitoring HPAIV infections in wild carnivore mammals to detect the potential virus spreading in nature.
  • Hesham Nasser, Ryo Shimizu, Jumpei Ito, Akatsuki Saito, Kei Sato, Terumasa Ikeda, Keita Matsuno, Naganori Nao, Hirofumi Sawa, Mai Kishimoto, Shinya Tanaka, Masumi Tsuda, Lei Wang, Yoshikata Oda, Marie Kato, Zannatul Ferdous, Hiromi Mouri, Kenji Shishido, Takasuke Fukuhara, Tomokazu Tamura, Rigel Suzuki, Hayato Ito, Daichi Yamasoba, Izumi Kimura, Naoko Misawa, Keiya Uriu, Yusuke Kosugi, Shigeru Fujita, Mai Suganami, Mika Chiba, Ryo Yoshimura, So Nakagawa, Jiaqi Wu, Akifumi Takaori-Kondo, Kotaro Shirakawa, Kayoko Nagata, Yasuhiro Kazuma, Ryosuke Nomura, Yoshihito Horisawa, Yusuke Tashiro, Yugo Kawai, Takashi Irie, Ryoko Kawabata, MST Monira Begum, Otowa Takahashi, Kimiko Ichihara, Takamasa Ueno, Chihiro Motozono, Mako Toyoda, Yuri L. Tanaka, Erika P. Butlertanaka, Maya Shofa, Kazuo Takayama, Rina Hashimoto, Sayaka Deguchi, Takao Hashiguchi, Tateki Suzuki, Kanako Kimura, Jiei Sasaki, Yukari Nakajima, Kaori Tabata
    STAR Protocols 3 (4) 101773 - 101773 2666-1667 2022/12
  • Akatsuki Saito, Tomokazu Tamura, Jiri Zahradnik, Sayaka Deguchi, Koshiro Tabata, Yuki Anraku, Izumi Kimura, Jumpei Ito, Daichi Yamasoba, Hesham Nasser, Mako Toyoda, Kayoko Nagata, Keiya Uriu, Yusuke Kosugi, Shigeru Fujita, Maya Shofa, Mst Monira Begum, Ryo Shimizu, Yoshitaka Oda, Rigel Suzuki, Hayato Ito, Naganori Nao, Lei Wang, Masumi Tsuda, Kumiko Yoshimatsu, Jin Kuramochi, Shunsuke Kita, Kaori Sasaki-Tabata, Hideo Fukuhara, Katsumi Maenaka, Yuki Yamamoto, Tetsuharu Nagamoto, Hiroyuki Asakura, Mami Nagashima, Kenji Sadamasu, Kazuhisa Yoshimura, Takamasa Ueno, Gideon Schreiber, Akifumi Takaori-Kondo, Kotaro Shirakawa, Hirofumi Sawa, Takashi Irie, Takao Hashiguchi, Kazuo Takayama, Keita Matsuno, Shinya Tanaka, Terumasa Ikeda, Takasuke Fukuhara, Kei Sato
    Cell host & microbe 30 (11) 1540 - 1555 2022/11/09 
    The SARS-CoV-2 Omicron BA.2.75 variant emerged in May 2022. BA.2.75 is a BA.2 descendant but is phylogenetically distinct from BA.5, the currently predominant BA.2 descendant. Here, we show that BA.2.75 has a greater effective reproduction number and different immunogenicity profile than BA.5. We determined the sensitivity of BA.2.75 to vaccinee and convalescent sera as well as a panel of clinically available antiviral drugs and antibodies. Antiviral drugs largely retained potency, but antibody sensitivity varied depending on several key BA.2.75-specific substitutions. The BA.2.75 spike exhibited a profoundly higher affinity for its human receptor, ACE2. Additionally, the fusogenicity, growth efficiency in human alveolar epithelial cells, and intrinsic pathogenicity in hamsters of BA.2.75 were greater than those of BA.2. Our multilevel investigations suggest that BA.2.75 acquired virological properties independent of BA.5, and the potential risk of BA.2.75 to global health is greater than that of BA.5.
  • Shinsuke Toba, Akihiko Sato, Makoto Kawai, Yoshiyuki Taoda, Yuto Unoh, Shinji Kusakabe, Haruaki Nobori, Shota Uehara, Kentaro Uemura, Keiichi Taniguchi, Masanori Kobayashi, Takeshi Noshi, Ryu Yoshida, Akira Naito, Takao Shishido, Junki Maruyama, Slobodan Paessler, Michael J Carr, William W Hall, Kumiko Yoshimatsu, Jiro Arikawa, Keita Matsuno, Yoshihiro Sakoda, Michihito Sasaki, Yasuko Orba, Hirofumi Sawa, Hiroshi Kida
    Proceedings of the National Academy of Sciences of the United States of America 119 (36) e2206104119  2022/09/06 
    Viral hemorrhagic fevers caused by members of the order Bunyavirales comprise endemic and emerging human infections that are significant public health concerns. Despite the disease severity, there are few therapeutic options available, and therefore effective antiviral drugs are urgently needed to reduce disease burdens. Bunyaviruses, like influenza viruses (IFVs), possess a cap-dependent endonuclease (CEN) that mediates the critical cap-snatching step of viral RNA transcription. We screened compounds from our CEN inhibitor (CENi) library and identified specific structural compounds that are 100 to 1,000 times more active in vitro than ribavirin against bunyaviruses, including Lassa virus, lymphocytic choriomeningitis virus (LCMV), and Junin virus. To investigate their inhibitory mechanism of action, drug-resistant viruses were selected in culture. Whole-genome sequencing revealed that amino acid substitutions in the CEN region of drug-resistant viruses were located in similar positions as those of the CEN α3-helix loop of IFVs derived under drug selection. Thus, our studies suggest that CENi compounds inhibit both bunyavirus and IFV replication in a mechanistically similar manner. Structural analysis revealed that the side chain of the carboxyl group at the seventh position of the main structure of the compound was essential for the high antiviral activity against bunyaviruses. In LCMV-infected mice, the compounds significantly decreased blood viral load, suppressed symptoms such as thrombocytopenia and hepatic dysfunction, and improved survival rates. These data suggest a potential broad-spectrum clinical utility of CENis for the treatment of both severe influenza and hemorrhagic diseases caused by bunyaviruses.
  • 渡り鳥から採集したマダニ中のYezoウイルス遺伝子解析
    西野 綾乃, 立本 完吾, 井上 雄介, 石嶋 慧多, 黒田 雄大, Mendoza Milagros Virhuez, 原田 倫子, 朴 ウンシル, 下田 宙, 高野 愛, 仲村 昇, 森本 元, 松野 啓太, 前田 健
    日本獣医学会学術集会講演要旨集 (公社)日本獣医学会 165回 [DV2A - 09] 1347-8621 2022/09
  • Izumi Kimura, Daichi Yamasoba, Tomokazu Tamura, Naganori Nao, Tateki Suzuki, Yoshitaka Oda, Shuya Mitoma, Jumpei Ito, Hesham Nasser, Jiri Zahradnik, Keiya Uriu, Shigeru Fujita, Yusuke Kosugi, Lei Wang, Masumi Tsuda, Mai Kishimoto, Hayato Ito, Rigel Suzuki, Ryo Shimizu, M.S.T. Monira Begum, Kumiko Yoshimatsu, Kanako Terakado Kimura, Jiei Sasaki, Kaori Sasaki-Tabata, Yuki Yamamoto, Tetsuharu Nagamoto, Jun Kanamune, Kouji Kobiyama, Hiroyuki Asakura, Mami Nagashima, Kenji Sadamasu, Kazuhisa Yoshimura, Kotaro Shirakawa, Akifumi Takaori-Kondo, Jin Kuramochi, Gideon Schreiber, Ken J. Ishii, Takao Hashiguchi, Terumasa Ikeda, Akatsuki Saito, Takasuke Fukuhara, Shinya Tanaka, Keita Matsuno, Kei Sato
    Cell 185 (21) 3992 - 4007 0092-8674 2022/09 
    After the global spread of the SARS-CoV-2 Omicron BA.2, some BA.2 subvariants, including BA.2.9.1, BA.2.11, BA.2.12.1, BA.4, and BA.5, emerged in multiple countries. Our statistical analysis showed that the effective reproduction numbers of these BA.2 subvariants are greater than that of the original BA.2. Neutralization experiments revealed that the immunity induced by BA.1/2 infections is less effective against BA.4/5. Cell culture experiments showed that BA.2.12.1 and BA.4/5 replicate more efficiently in human alveolar epithelial cells than BA.2, and particularly, BA.4/5 is more fusogenic than BA.2. We further provided the structure of the BA.4/5 spike receptor-binding domain that binds to human ACE2 and considered how the substitutions in the BA.4/5 spike play roles in ACE2 binding and immune evasion. Moreover, experiments using hamsters suggested that BA.4/5 is more pathogenic than BA.2. Our multiscale investigations suggest that the risk of BA.2 subvariants, particularly BA.4/5, to global health is greater than that of original BA.2.
  • Wessam Mohamed Ahmed Mohamed, Mohamed Abdallah Mohamed Moustafa, May June Thu, Keita Kakisaka, Elisha Chatanga, Shohei Ogata, Naoki Hayashi, Yurie Taya, Yuma Ohari, Doaa Naguib, Yongjin Qiu, Keita Matsuno, Saw Bawm, Lat Lat Htun, Stephen C. Barker, Ken Katakura, Kimihito Ito, Nariaki Nonaka, Ryo Nakao
    Evolutionary Applications 15 (7) 1062 - 1078 1752-4571 2022/06/23 
    Ticks are the second most important vector capable of transmitting diseases affecting the health of both humans and animals. Amblyomma testudinarium Koch 1844 (Acari: Ixodidae), is a hard tick species having a wide geographic distribution in Asia. In this study, we analyzed the composition of A. testudinarium whole mitogenomes from various geographical regions in Japan and investigated the population structure, demographic patterns, and phylogeographic relationship with other ixodid species. In addition, we characterized a potentially novel tick species closely related to A. testudinarium from Myanmar. Phylogeographic inference and evolutionary dynamics based on the 15 mitochondrial coding genes supported that A. testudinarium population in Japan is resolved into a star-like haplogroup and suggested a distinct population structure of A. testudinarium from Amami island in Kyushu region. Correlation analysis using Mantel test statistics showed that no significant correlation was observed between the genetic and geographic distances calculated between the A. testudinarium population from different localities in Japan. Finally, demographic analyses, including mismatch analysis and Tajima's D test, suggested a possibility of recent population expansion occurred within Japanese haplogroup after a bottleneck event. Although A. testudinarium has been considered widespread and common in East and Southeast Asia, the current study suggested that potentially several cryptic Amblyomma spp. closely related to A. testudinarium are present in Asia.
  • Kien Trung LE, Norikazu Isoda, Lam Thanh Nguyen, Duc-Huy Chu, Long Van Nguyen, Minh Quang Phan, Diep Thi Nguyen, Tien Ngoc Nguyen, Tien Ngoc Tien, Tung Thanh LE, Takahiro Hiono, Keita Matsuno, Masatoshi Okamatsu, Yoshihiro Sakoda
    The Journal of veterinary medical science 84 (6) 860 - 868 2022/05/13 
    The impact of low pathogenicity avian influenza (LPAI) has been confirmed mainly in farms. Unlike apparent losses caused by the high pathogenicity avian influenza (HPAI), the LPAI impact has been hardly evaluated due to underestimating its spread and damage. In 2019, a questionnaire study was conducted in southern Vietnam to identify the specific risk factors of LPAI virus (LPAIV) circulation and to find associations between husbandry activities and LPAI prevalence. A multilevel regression analysis indicated that keeping Muscovy ducks during farming contributed to LPAIV positivity [Odds ratio=208.2 (95% confidence interval: 13.4-1.1×104)]. In cluster analysis, farmers willing to report avian influenza (AI) events and who agreed with the local AI control policy had a slightly lower risk for LPAIV infection although there was no significance in the correlation between farmer characteristics and LPAI occurrence. These findings indicated that keeping Muscovy ducks without appropriate countermeasures might increase the risk of LPAIV infection. Furthermore, specific control measures at the local level are effective for LPAIV circulation, and the improvement of knowledge about biosecurity and attitude contributes to reducing LPAI damage.
  • Daichi Yamasoba, Izumi Kimura, Hesham Nasser, Yuhei Morioka, Naganori Nao, Jumpei Ito, Keiya Uriu, Masumi Tsuda, Jiri Zahradnik, Kotaro Shirakawa, Rigel Suzuki, Mai Kishimoto, Yusuke Kosugi, Kouji Kobiyama, Teppei Hara, Mako Toyoda, Yuri L Tanaka, Erika P Butlertanaka, Ryo Shimizu, Hayato Ito, Lei Wang, Yoshitaka Oda, Yasuko Orba, Michihito Sasaki, Kayoko Nagata, Kumiko Yoshimatsu, Hiroyuki Asakura, Mami Nagashima, Kenji Sadamasu, Kazuhisa Yoshimura, Jin Kuramochi, Motoaki Seki, Ryoji Fujiki, Atsushi Kaneda, Tadanaga Shimada, Taka-Aki Nakada, Seiichiro Sakao, Takuji Suzuki, Takamasa Ueno, Akifumi Takaori-Kondo, Ken J Ishii, Gideon Schreiber, Hirofumi Sawa, Akatsuki Saito, Takashi Irie, Shinya Tanaka, Keita Matsuno, Takasuke Fukuhara, Terumasa Ikeda, Kei Sato
    Cell 185 (12) 2103 - 2115 2022/05/02 
    Soon after the emergence and global spread of the SARS-CoV-2 Omicron lineage BA.1, another Omicron lineage, BA.2, began outcompeting BA.1. The results of statistical analysis showed that the effective reproduction number of BA.2 is 1.4-fold higher than that of BA.1. Neutralization experiments revealed that immunity induced by COVID vaccines widely administered to human populations is not effective against BA.2, similar to BA.1, and that the antigenicity of BA.2 is notably different from that of BA.1. Cell culture experiments showed that the BA.2 spike confers higher replication efficacy in human nasal epithelial cells and is more efficient in mediating syncytia formation than the BA.1 spike. Furthermore, infection experiments using hamsters indicated that the BA.2 spike-bearing virus is more pathogenic than the BA.1 spike-bearing virus. Altogether, the results of our multiscale investigations suggest that the risk of BA.2 to global health is potentially higher than that of BA.1.
  • Mohamed Abdallah Mohamed Moustafa, Wessam Mohamed Ahmed Mohamed, Alice C C Lau, Elisha Chatanga, Yongjin Qiu, Naoki Hayashi, Doaa Naguib, Kozue Sato, Ai Takano, Keita Matsuno, Nariaki Nonaka, DeMar Taylor, Hiroki Kawabata, Ryo Nakao
    Computational and structural biotechnology journal 20 1979 - 1992 2022/04 
    Research on vector-associated microbiomes has been expanding due to increasing emergence of vector-borne pathogens and awareness of the importance of symbionts in the vector physiology. However, little is known about microbiomes of argasid (or soft-bodied) ticks due to limited access to specimens. We collected four argasid species (Argas japonicus, Carios vespertilionis, Ornithodoros capensis, and Ornithodoros sawaii) from the nests or burrows of their vertebrate hosts. One laboratory-reared argasid species (Ornithodoros moubata) was also included. Attempts were then made to isolate and characterize potential symbionts/pathogens using arthropod cell lines. Microbial community structure was distinct for each tick species. Coxiella was detected as the predominant symbiont in four tick species where dual symbiosis between Coxiella and Rickettsia or Coxiella and Francisella was observed in C. vespertilionis and O. moubata, respectively. Of note, A. japonicus lacked Coxiella and instead had Occidentia massiliensis and Thiotrichales as alternative symbionts. Our study found strong correlation between tick species and life stage. We successfully isolated Oc. massiliensis and characterized potential pathogens of genera Ehrlichia and Borrelia. The results suggest that there is no consistent trend of microbiomes in relation to tick life stage that fit all tick species and that the final interpretation should be related to the balance between environmental bacterial exposure and endosymbiont ecology. Nevertheless, our findings provide insights on the ecology of tick microbiomes and basis for future investigations on the capacity of argasid ticks to carry novel pathogens with public health importance.
  • Kazuya TAKEHANA, Shigehisa KAWAKAMI, Chatchote Thitaram, Keita MATSUNO
    Japanese Journal of Zoo and Wildlife Medicine 27 (1) 17 - 27 1342-6133 2022/03/01
  • Rigel Suzuki, Daichi Yamasoba, Izumi Kimura, Lei Wang, Mai Kishimoto, Jumpei Ito, Yuhei Morioka, Naganori Nao, Hesham Nasser, Keiya Uriu, Yusuke Kosugi, Masumi Tsuda, Yasuko Orba, Michihito Sasaki, Ryo Shimizu, Ryoko Kawabata, Kumiko Yoshimatsu, Hiroyuki Asakura, Mami Nagashima, Kenji Sadamasu, Kazuhisa Yoshimura, Hirofumi Sawa, Terumasa Ikeda, Takashi Irie, Keita Matsuno, Shinya Tanaka, Takasuke Fukuhara, Kei Sato
    Nature 603 (7902) 700 - 705 2022/02/01 
    The emergence of a new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant, Omicron, is an urgent global health concern (ref.1). Our statistical modelling suggests that Omicron has spread more rapidly than the Delta variant in several countries including South Africa. Cell culture experiments show that Omicron is less fusogenic than Delta and an ancestral SARS-CoV-2 strain. Although the spike (S) protein of Delta is efficiently cleaved into two subunits, which facilitates cell-cell fusion2,3, Omicron S is less efficiently cleaved compared to Delta S and ancestral SARS-CoV-2 S. Furthermore, in a hamster model, Omicron shows decreased lung infectivity and is less pathogenic compared to Delta and ancestral SARS-CoV-2.
  • Cindy M Spruit, Xueyong Zhu, Ilhan Tomris, María Ríos Carrasco, Alvin X Han, Frederik Broszeit, Roosmarijn van der Woude, Kim M Bouwman, Michel M T Luu, Keita Matsuno, Yoshihiro Sakoda, Colin A Russell, Ian A Wilson, Geert-Jan Boons, Robert P de Vries
    Journal of virology 96 (5) e02120-21  2022/01/19 
    Influenza A viruses (IAV) initiate infection by binding to glycans with terminal sialic acids on the cell surface. Hosts of IAV variably express two major forms of sialic acid, N-acetylneuraminic acid (NeuAc) and N-glycolylneuraminic acid (NeuGc). NeuGc is produced in most mammals including horses and pigs, but is absent in humans, ferrets, and birds. The only known naturally occurring IAVs that exclusively bind NeuGc are extinct highly pathogenic equine H7N7 viruses. We determined the crystal structure of a representative equine H7 hemagglutinin (HA) in complex with NeuGc and observed high similarity in the receptor-binding domain with an avian H7 HA. To determine the molecular basis for NeuAc and NeuGc specificity, we performed systematic mutational analyses, based on the structural insights, on two distant avian H7 HAs and an H15 HA. We found that mutation A135E is key for binding α2,3-linked NeuGc but does not abolish NeuAc binding. Additional mutations S128T, I130V, T189A, and K193R converted the specificity from NeuAc to NeuGc. We investigated the residues at positions 128, 130, 135, 189, and 193 in a phylogenetic analysis of avian and equine H7 HAs. This revealed a clear distinction between equine and avian residues. The highest variability was observed at key position 135, of which only the equine glutamic acid led to NeuGc binding. These results demonstrate that genetically distinct H7 and H15 HAs can be switched from NeuAc to NeuGc binding and vice versa after introduction of several mutations, providing insights into the adaptation of H7 viruses to NeuGc receptors. (250 words) Importance Influenza A viruses cause millions of cases of severe illness and deaths annually. To initiate infection and replicate, the virus first needs to bind to a structure on the cell surface, like a key fitting in a lock. For influenza A viruses, these 'keys' (receptors) on the cell surface are chains of sugar molecules (glycans). The terminal sugar on these glycans is often either N-acetylneuraminic acid (NeuAc) or N-glycolylneuraminic acid (NeuGc). Most influenza A viruses bind NeuAc, but a small minority binds NeuGc. NeuGc is present in species like horses, pigs, and mice, but not in humans, ferrets, and birds. Here, we investigated the molecular determinants of NeuGc specificity and the origin of viruses that bind NeuGc.
  • Keiichi Taniguchi, Yoshinori Ando, Masanori Kobayashi, Shinsuke Toba, Haruaki Nobori, Takao Sanaki, Takeshi Noshi, Makoto Kawai, Ryu Yoshida, Akihiko Sato, Takao Shishido, Akira Naito, Keita Matsuno, Masatoshi Okamatsu, Yoshihiro Sakoda, Hiroshi Kida
    Viruses 14 (1) 111  2022/01/08 
    Human infections caused by the H5 highly pathogenic avian influenza virus (HPAIV) sporadically threaten public health. The susceptibility of HPAIVs to baloxavir acid (BXA), a new class of inhibitors for the influenza virus cap-dependent endonuclease, has been confirmed in vitro, but it has not yet been fully characterized. Here, the efficacy of BXA against HPAIVs, including recent H5N8 variants, was assessed in vitro. The antiviral efficacy of baloxavir marboxil (BXM) in H5N1 virus-infected mice was also investigated. BXA exhibited similar in vitro activities against H5N1, H5N6, and H5N8 variants tested in comparison with seasonal and other zoonotic strains. Compared with oseltamivir phosphate (OSP), BXM monotherapy in mice infected with the H5N1 HPAIV clinical isolate, the A/Hong Kong/483/1997 strain, also caused a significant reduction in viral titers in the lungs, brains, and kidneys, thereby preventing acute lung inflammation and reducing mortality. Furthermore, compared with BXM or OSP monotherapy, combination treatments with BXM and OSP using a 48-h delayed treatment model showed a more potent effect on viral replication in the organs, accompanied by improved survival. In conclusion, BXM has a potent antiviral efficacy against H5 HPAIV infections.
  • Kosuke Soda, Hiroichi Ozaki, Hiroshi Ito, Tatsufumi Usui, Masatoshi Okamatsu, Keita Matsuno, Yoshihiro Sakoda, Tsuyoshi Yamaguchi, Toshihiro Ito
    The Journal of veterinary medical science 83 (12) 1891 - 1898 2021/12/02 
    Large highly pathogenic avian influenza (HPAI) outbreaks caused by clade 2.3.4.4e H5N6 viruses occurred in Japan during the 2016-2017 winter. To date, several reports regarding these outbreaks have been published, however a comprehensive study including geographical and time course validations has not been performed. Herein, 58 Japanese HPAI virus (HPAIV) isolates from the 2016-2017 season were added for phylogenetic analyses and the antigenic relationships among the causal viruses were elucidated. The locations where HPAIVs were found in the early phase of the outbreaks were clustered into three regions. Genotypes C1, C5, and C6-8 HPAIVs were found in specific areas. Two strains had phylogenetically distinct hemagglutinin (HA) and non-structural (NS) genes from other previously identified strains, respectively. The estimated latest divergence date between the viral genotypes suggests that genetic reassortment occurred in bird populations before their winter migration to Japan. Antigenic differences in 2016-2017 HPAIVs were not observed, suggesting that antibody pressure in the birds did not contribute to the selection of HPAIV genotypes. In the late phase, the majority of HPAI cases in wild birds occurred south of the lake freezing line. At the end of the outbreak, HPAI re-occurred in East coast region, which may be due to the spring migration route of Anas bird species. These trends were similar to those observed in the 2010-2011 outbreaks, suggesting there is a typical pattern of seeding and dissemination of HPAIV in Japan.
  • Nodoka Kasajima, Keita Matsuno, Hiroko Miyamoto, Masahiro Kajihara, Manabu Igarashi, Ayato Takada
    Viruses 13 (11) 2316  2021/11/20 
    Viral protein 35 (VP35) of Ebola virus (EBOV) is a multifunctional protein that mainly acts as a viral polymerase cofactor and an interferon antagonist. VP35 interacts with the viral nucleoprotein (NP) and double-stranded RNA for viral RNA transcription/replication and inhibition of type I interferon (IFN) production, respectively. The C-terminal portion of VP35, which is termed the IFN-inhibitory domain (IID), is important for both functions. To further identify critical regions in this domain, we analyzed the physical properties of the surface of VP35 IID, focusing on hydrophobic patches, which are expected to be functional sites that are involved in interactions with other molecules. Based on the known structural information of VP35 IID, three hydrophobic patches were identified on its surface and their biological importance was investigated using minigenome and IFN-β promoter-reporter assays. Site-directed mutagenesis revealed that some of the amino acid substitutions that were predicted to disrupt the hydrophobicity of the patches significantly decreased the efficiency of viral genome replication/transcription due to reduced interaction with NP, suggesting that the hydrophobic patches might be critical for the formation of a replication complex through the interaction with NP. It was also found that the hydrophobic patches were involved in the IFN-inhibitory function of VP35. These results highlight the importance of hydrophobic patches on the surface of EBOV VP35 IID and also indicate that patch analysis is useful for the identification of amino acid residues that directly contribute to protein functions.
  • Kien Trung Le, Mark A Stevenson, Norikazu Isoda, Lam Thanh Nguyen, Duc-Huy Chu, Tien Ngoc Nguyen, Long Van Nguyen, Tien Ngoc Tien, Tung Thanh Le, Keita Matsuno, Masatoshi Okamatsu, Yoshihiro Sakoda
    Transboundary and emerging diseases 1 - 14 2021/11/04 
    In South Vietnam, live bird markets (LBMs) are key in the value chain of poultry products and spread of avian influenza virus (AIV) although they may not be the sole determinant of AIV prevalence. For this reason, a risk analysis of AIV prevalence was conducted accounting for all value chain factors. A cross-sectional study of poultry flock managers and poultry on backyard farms, commercial (high biosecurity) farms, LBMs and poultry delivery stations (PDSs) in four districts of Vinh Long province was conducted between December 2016 and August 2017. A total of 3597 swab samples were collected from birds from 101 backyard farms, 50 commercial farms, 58 sellers in LBMs and 19 traders in PDSs. Swab samples were submitted for AIV isolation. At the same time a questionnaire was administered to flock managers asking them to provide details of their knowledge, attitude and practices related to avian influenza. Multiple correspondence analysis and a mixed-effects multivariable logistic regression model were developed to identify enterprise and flock manager characteristics that increased the risk of AIV positivity. A total of 274 birds were positive for AIV isolation, returning an estimated true prevalence of 7.6% [95% confidence interval (CI): 6.8%-8.5%]. The odds of a bird being AIV positive if it was from an LBM or PDS were 45 (95% CI: 3.4-590) and 25 (95% CI: 1.4-460), respectively, times higher to the odds of a bird from a commercial poultry farm being AIV positive. The odds of birds being AIV positive for respondents with a mixed (uncertain or inconsistent) level and a low level of knowledge about AI were 5.0 (95% CI: 0.20-130) and 3.5 (95% CI: 0.2-62), respectively, times higher to the odd of birds being positive for respondents with a good knowledge of AI. LBMs and PDSs should receive specific emphasis in AI control programs in Vietnam. Our findings provide evidence to support the hypothesis that incomplete respondent knowledge of AI and AIV spread mechanism were associated with an increased risk of AIV positivity. Delivery of education programs specifically designed for those in each enterprise will assist in this regard. The timing and frequency of delivery of education programs are likely to be important if the turnover of those working in LBMs and PDSs is high.
  • Devinda S Muthusinghe, Kenta Shimizu, Sithumini M W Lokupathirage, Zhouoxing Wei, Yomani D Sarathkumara, G R Amanda Fonseka, Pavani Senarathne, Nobuo Koizumi, Tomonori Kawakami, Akio Koizumi, Chaminda Wickramasinghe, Hideki Ebihara, Keita Matsuno, Yoshimi Tsuda, Jiro Arikawa, Chandika D Gamage, Kumiko Yoshimatsu
    Viruses 13 (10) 1984  2021/10/02 
    We reported the genetic evidence of circulating hantaviruses from small mammals captured in a chronic kidney disease of unknown etiology (CKDu) hotspot area of Sri Lanka. The high seroprevalence of anti-hantavirus antibodies against Thailand orthohantavirus (THAIV) has been reported among CKDu patients and rodents in Sri Lankan CKDu hotspots. We captured 116 small mammals from CKDu endemic regions in the Polonnaruwa District of Sri Lanka. Seven animals (five out of 11 Mus booduga and two out of 99 Rattus rattus) were PCR-positive for the hantavirus. A rat-borne sequence was grouped with a THAIV-like Anjozorobe virus. In contrast, Mus-borne sequences belonged to the THAIV lineage, suggesting a novel orthohantavirus species according to the phylogenetic analyses and whole-genome comparisons. Our genetic evidence indicates the presence of two THAIV-related viruses circulating in this CKDu endemic area, suggesting a basis for further investigations to identify the infectious virus in patients with CKDu and the CKDu induction mechanism of these viruses.
  • Fumihiro Kodama, Hiroki Yamaguchi, Eunsil Park, Kango Tatemoto, Mariko Sashika, Ryo Nakao, Yurino Terauchi, Keita Mizuma, Yasuko Orba, Hiroaki Kariwa, Katsuro Hagiwara, Katsunori Okazaki, Akiko Goto, Rika Komagome, Masahiro Miyoshi, Takuya Ito, Kimiaki Yamano, Kentaro Yoshii, Chiaki Funaki, Mariko Ishizuka, Asako Shigeno, Yukari Itakura, Lesley Bell-Sakyi, Shunji Edagawa, Atsushi Nagasaka, Yoshihiro Sakoda, Hirofumi Sawa, Ken Maeda, Masayuki Saijo, Keita Matsuno
    Nature communications 12 (1) 5539 - 5539 2021/09/20 
    The increasing burden of tick-borne orthonairovirus infections, such as Crimean-Congo hemorrhagic fever, is becoming a global concern for public health. In the present study, we identify a novel orthonairovirus, designated Yezo virus (YEZV), from two patients showing acute febrile illness with thrombocytopenia and leukopenia after tick bite in Hokkaido, Japan, in 2019 and 2020, respectively. YEZV is phylogenetically grouped with Sulina virus detected in Ixodes ricinus ticks in Romania. YEZV infection has been confirmed in seven patients from 2014-2020, four of whom were co-infected with Borrelia spp. Antibodies to YEZV are found in wild deer and raccoons, and YEZV RNAs have been detected in ticks from Hokkaido. In this work, we demonstrate that YEZV is highly likely to be the causative pathogen of febrile illness, representing the first report of an endemic infection associated with an orthonairovirus potentially transmitted by ticks in Japan.
  • Shohei Ogata, Juan Antonio Cristian Pereira, Loza Vega Ariel Jhonny, Herbas Perez Gladys Carolina, Keita Matsuno, Yasuko Orba, Hirofumi Sawa, Fumihiko Kawamori, Nariaki Nonaka, Ryo Nakao
    Veterinary Sciences 8 (9) 188 - 188 2021/09/07 
    Latin American countries produce more than a quarter of the world’s beef and are a major global supplier of livestock protein. Tick-borne diseases (TBDs) are a major constraint to the livestock industry worldwide, including in Latin America. The aim of this study was to detect and characterise tick-borne pathogens in cattle from Santa Cruz, Bolivia, where no detailed epidemiological data are available. Blood samples were collected from 104 cattle. Apicomplexan parasites were detected by nested PCR amplification of the 18S ribosomal RNA gene (rDNA), and Anaplasmataceae was screened by the PCR amplification of 16S rDNA, followed by characterisation based on the heat shock protein and citrate synthase gene sequences. Babesia infection was observed in nine cattle (one Babesia bovis and eight Babesia bigemina), while Anaplasmataceae infection was detected in thirty-two cattle. A sequencing analysis confirmed the presence of Anaplasma marginale and Anaplasma platys-like. These results provide the first molecular evidence for the four above-mentioned tick-borne pathogens in cattle in Bolivia. This information improves our understanding of the epidemiology of TBDs and will help in formulating appropriate and improved pathogen control strategies.
  • Wessam Mohamed Ahmed Mohamed, Mohamed Abdallah Mohamed Moustafa, Samuel Kelava, Dayana Barker, Keita Matsuno, Nariaki Nonaka, Renfu Shao, Ben J. Mans, Stephen C. Barker, Ryo Nakao
    Ticks and Tick-borne Diseases 13 (1) 101832 - 101832 1877-959X 2021/09 
    High-throughput sequencing (HTS) technology has profoundly been involved in sequencing whole genomes of several organisms in a fast and cost-effective manner. Although HTS provides an alternative biomonitoring method to the time-consuming and taxonomy-expertise dependent morphological approach, still we cannot rule out the possibility of the impediment and misidentification biases. In this article we aim to retrieve whole mitochondrial genome (mitogenome) sequences from publicly available raw sequencing data for phylogenetic comparison of Ixodes persulcatus. For this comparison, we sequenced whole mitogenomes of four I. persulcatus ticks from Japan and constructed mitogenomes from raw sequencing data of 74 I. persulcatus ticks from China. Bayesian phylogenetic trees were inferred by the concatenated fifteen mitochondrial genes. We further tested our results by the phylogenetic analysis of cytochrome c oxidase subunit 1 (cox1) gene and internal transcribed spacer 2 (ITS2) sequences. Our findings showed that 70 constructed mitogenomes from China were clustered with the sequenced four mitogenomes of I. persulcatus from Japan. We also revealed that mitogenome sequences retrieved from two data sets CRR142297 and CRR142298 were clustered with Ixodes nipponensis. Moreover, other two mitogenome sequences from CRR142310 and CRR142311 formed a clade with Ixodes pavlovskyi. The phylogenetic analysis of cox1 gene and ITS2 sequences confirmed the identification errors of these four samples. The overall phylogenetics in our study concluded that accurate morphological identification is necessary before implementing HTS to avoid any misidentification biases.
  • Ben J Mans, Samuel Kelava, Ronel Pienaar, Jonathan Featherston, Minique H de Castro, Juan Quetglas, Will K Reeves, Lance A Durden, Myrna M Miller, Theresa M Laverty, Renfu Shao, Ai Takano, Hiroki Kawabata, Mohamed Abdallah Mohamed Moustafa, Ryo Nakao, Keita Matsuno, Telleasha L Greay, Kimberly L Evasco, Dayana Barker, Stephen C Barker
    Ticks and tick-borne diseases 12 (4) 101688 - 101688 2021/07 
    Argasid systematics remains controversial with widespread adherence to the Hoogstraal (1985) classification scheme, even though it does not reflect evolutionary relationships and results in paraphyly for the main genera of soft ticks (Argasidae), namely Argas and Ornithodoros. The alternative classification scheme, proposed by Klompen and Oliver (1993), has problems of its own: most notably paraphyly of the subgenus Pavlovskyella and the controversial grouping together of the subgenera Alectorobius, Antricola, Carios, Chiropterargas, Nothoaspis, Parantricola, Reticulinasus and Subparmatus into the genus Carios. Recent phylogenetic analyses of 18S/28S rRNA sequences and mitochondrial genomes agree with the scheme of Klompen and Oliver (1993), with regard to the paraphyly of Pavlovskyella, placement of Alveonasus, Ogadenus, Proknekalia and Secretargas in the Argasinae and placement of Carios and Chiropterargas in the Ornithodorinae (Mans et al., 2019). The Carios clade and its constituent subgenera remain controversial, since the phylogenetic position of its type species Carios (Carios) vespertilionis Latreille, 1796 (formerly Argas vespertilionis) has not been determined with confidence. The current study aimed to resolve Carios sensu lato Klompen and Oliver, 1993, and Carios sensu stricto Hoogstraal, 1985, by determining and analysing phylogenetic nuclear and mitochondrial markers for C. (C.) vespertilionis. Both the nuclear and mitochondrial markers support placement of Carios s.s. within the subfamily Ornithodorinae, but to the exclusion of the clade that includes the 6 other subgenera that are part of Carios s.l. Klompen and Oliver (1993), namely Alectorobius, Antricola, Nothoaspis, Parantricola, Reticulinasus and Subparmatus. These 6 subgenera form a monophyletic clade that might be placed as new subgenera within the genus Alectorobius, or elevated to genera. Given the substantial differences in biology among these subgenera, we propose that these 6 subgenera be elevated to genera. Thus, we propose to modify the classification scheme of Mans et al. (2019) so that the subfamily Argasinae now has six genera, Alveonasus, Argas (subgenera Argas and Persicargas), Navis, Ogadenus, Proknekalia and Secretargas, and the subfamily Ornithodorinae has nine genera, Alectorobius, Antricola (subgenera Antricola and Parantricola), Carios, Chiropterargas, Nothoaspis, Ornithodoros (subgenera Microargas, Ornamentum, Ornithodoros, Pavlovskyella and Theriodoros), Otobius, Reticulinasus and Subparmatus (genera indicated in bold).
  • Yurie Taya, Gohta Kinoshita, Wessam Mohamed Ahmed Mohamed, Mohamed Abdallah Mohamed Moustafa, Shohei Ogata, Elisha Chatanga, Yuma Ohari, Kodai Kusakisako, Keita Matsuno, Nariaki Nonaka, Ryo Nakao
    Microorganisms 9 (5) 2021/05/13 
    Ticks serve as important vectors of a variety of pathogens. Recently, the viral and prokaryotic microbiomes in ticks have been explored using next-generation sequencing to understand the physiology of ticks and their interactions with pathogens. However, analyses of eukaryotic communities in ticks are limited, owing to the lack of suitable methods. In this study, we developed new methods to selectively amplify microeukaryote genes in tick-derived DNA by blocking the amplification of the 18S rRNA gene of ticks using artificial nucleic acids: peptide nucleic acids (PNAs) and locked nucleic acids (LNAs). In addition, another PCR using non-metazoan primers, referred to as UNonMet-PCR, was performed for comparison. We performed each PCR using tick-derived DNA and sequenced the amplicons using the Illumina MiSeq platform. Almost all sequences obtained by conventional PCR were derived from ticks, whereas the proportion of microeukaryotic reads and alpha diversity increased upon using the newly developed method. Additionally, the PNA- or LNA-based methods were suitable for paneukaryotic analyses, whereas the UNonMet-PCR method was particularly sensitive to fungi. The newly described methods enable analyses of the eukaryotic microbiome in ticks. We expect the application of these methods to improve our understanding of the tick microbiome.
  • Naoki Nomura, Keita Matsuno, Masashi Shingai, Marumi Ohno, Toshiki Sekiya, Ryosuke Omori, Yoshihiro Sakoda, Robert G Webster, Hiroshi Kida
    Virology 557 55 - 61 2021/05 
    Genetic reassortment of influenza A viruses through cross-species transmission contributes to the generation of pandemic influenza viruses. To provide information on the ecology of influenza viruses, we have been conducting a global surveillance of zoonotic influenza and establishing an influenza virus library. Of 4580 influenza virus strains in the library, 3891 have been isolated from over 70 different bird species. The remaining 689 strains were isolated from humans, pigs, horses, seal, whale, and the environment. Phylogenetic analyses of the HA genes of the library isolates demonstrate that the library strains are distributed to all major known clusters of the H1, H2 and H3 subtypes of HA genes that are prevalent in humans. Since past pandemic influenza viruses are most likely genetic reassortants of zoonotic and seasonal influenza viruses, a vast collection of influenza A virus strains from various hosts should be useful for vaccine preparation and diagnosis for future pandemics.
  • Hayato Harima, Yasuko Orba, Shiho Torii, Yongjin Qiu, Masahiro Kajihara, Yoshiki Eto, Naoya Matsuta, Bernard M Hang'ombe, Yuki Eshita, Kentaro Uemura, Keita Matsuno, Michihito Sasaki, Kentaro Yoshii, Ryo Nakao, William W Hall, Ayato Takada, Takashi Abe, Michael T Wolfinger, Martin Simuunza, Hirofumi Sawa
    Scientific reports 11 (1) 4883 - 4883 2021/03/01 
    Tick-borne flaviviruses (TBFVs) infect mammalian hosts through tick bites and can cause various serious illnesses, such as encephalitis and hemorrhagic fevers, both in humans and animals. Despite their importance to public health, there is limited epidemiological information on TBFV infection in Africa. Herein, we report that a novel flavivirus, Mpulungu flavivirus (MPFV), was discovered in a Rhipicephalus muhsamae tick in Zambia. MPFV was found to be genetically related to Ngoye virus detected in ticks in Senegal, and these viruses formed a unique lineage in the genus Flavivirus. Analyses of dinucleotide contents of flaviviruses indicated that MPFV was similar to those of other TBFVs with a typical vertebrate genome signature, suggesting that MPFV may infect vertebrate hosts. Bioinformatic analyses of the secondary structures in the 3'-untranslated regions (UTRs) revealed that MPFV exhibited unique exoribonuclease-resistant RNA (xrRNA) structures. Utilizing biochemical approaches, we clarified that two xrRNA structures of MPFV in the 3'-UTR could prevent exoribonuclease activity. In summary, our findings provide new information regarding the geographical distribution of TBFV and xrRNA structures in the 3'-UTR of flaviviruses.
  • Makoto Nagai, Tamaki Okabayashi, Masataka Akagami, Aya Matsuu, Yoshikazu Fujimoto, Md Abul Hashem, Hirohisa Mekata, Ryo Nakao, Keita Matsuno, Yukie Katayama, Mami Oba, Tsutomu Omatsu, Tetsuo Asai, Keisuke Nakagawa, Hiroshi Ito, Hiroo Madarame, Kazuhiro Kawai, Toshihiro Ito, Nariaki Nonaka, Kyoko Tsukiyama-Kohara, Yasuo Inoshima, Tetsuya Mizutani, Naoaki Misawa
    Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases 88 104664 - 104664 2021/03 
    Recently, hepe-astrovirus-like RNA viruses named bastroviruses (BastVs), have been found in human, pig, bat, and rat fecal samples. In this study, we determined nearly complete genome sequences of four BastVs in the feces of healthy pigs. Genetic characterization revealed that these porcine BastVs (PBastVs) and BastVs from other animals including humans, had the same genome organization, that is, they contained three predicted conserved domains of viral methyltransferase, RNA helicase, and RdRp in the nonstructural ORF1 and the astrovirus capsid domain in the structural ORF2. Phylogenetic analyses using RNA-dependent RNA polymerase and the capsid region revealed that PBastVs branched with bat and rat BastVs; however, the groups formed by each host were distantly related to human BastVs. Pairwise amino acid sequence comparison demonstrated that PBastVs shared 95.2-98.6% and 76.1-95.5% sequence identity among each other in the ORF1 and ORF2 regions, respectively; the sequence identities between PBastVs and BastVs from other animals were 21.4-42.5% and 9.1-20.6% in the ORF1 and ORF2 regions, respectively. This suggested that BastVs were derived from a common ancestor but evolved independently in each host population during a prolonged period. Putative recombination events were identified in the PBastV genome, suggesting that PBastVs gain sequence diversity and flexibility through recombination events. In an analysis of previously obtained metagenomic data, PBastV sequence reads were detected in 7.3% (23/315) of fecal samples from pigs indicating that PBastVs are distributed among pig populations in Japan.
  • Yasuko Orba, Keita Matsuno, Ryo Nakao, Kirill Kryukov, Yumi Saito, Fumihiko Kawamori, Ariel Loza Vega, Tokiko Watanabe, Tadashi Maemura, Michihito Sasaki, William W Hall, Roy A Hall, Juan Antonio Pereira, So Nakagawa, Hirofumi Sawa
    The Journal of general virology 102 (3) 2021/03 
    The genus Flavivirus includes a range of mosquito-specific viruses in addition to well-known medically important arboviruses. Isolation and comprehensive genomic analyses of viruses in mosquitoes collected in Bolivia resulted in the identification of three novel flavivirus species. Psorophora flavivirus (PSFV) was isolated from Psorophora albigenu. The coding sequence of the PSFV polyprotein shares 60 % identity with that of the Aedes-associated lineage II insect-specific flavivirus (ISF), Marisma virus. Isolated PSFV replicates in both Aedes albopictus- and Aedes aegypti-derived cells, but not in mammalian Vero or BHK-21 cell lines. Two other flaviviruses, Ochlerotatus scapularis flavivirus (OSFV) and Mansonia flavivirus (MAFV), which were identified from Ochlerotatus scapularis and Mansonia titillans, respectively, group with the classical lineage I ISFs. The protein coding sequences of these viruses share only 60 and 40 % identity with the most closely related of known lineage I ISFs, including Xishuangbanna aedes flavivirus and Sabethes flavivirus, respectively. Phylogenetic analysis suggests that MAFV is clearly distinct from the groups of the current known Culicinae-associated lineage I ISFs. Interestingly, the predicted amino acid sequence of the MAFV capsid protein is approximately two times longer than that of any of the other known flaviviruses. Our results indicate that flaviviruses with distinct features can be found at the edge of the Bolivian Amazon basin at sites that are also home to dense populations of human-biting mosquitoes.
  • Enkhbold Bazarragchaa, Norikazu Isoda, Taksoo Kim, Madoka Tetsuo, Satoshi Ito, Keita Matsuno, Yoshihiro Sakoda
    Viruses 13 (2) 2021/02/20 
    Classical swine fever virus (CSFV) in the wild boar population has been spreading in Japan, alongside outbreaks on pigs, since classical swine fever (CSF) reemerged in September 2018. The vaccination using oral bait vaccine was initially implemented in Gifu prefecture in March 2019. In the present study, antibodies against CSFV in wild boar were assessed in 1443 captured and dead wild boars in Gifu prefecture. After the implementation of oral vaccination, the increase of the proportion of seropositive animals and their titer in wild boars were confirmed. Quantitative analysis of antigen and antibodies against CSFV in wild boar implies potential disease diversity in the wild boar population. Animals with status in high virus replication (Ct < 30) and non- or low-immune response were confirmed and were sustained at a certain level after initial oral vaccination. Through continuous vaccination periods, the increase of seroprevalence among wild boar and the decrease of CSFV-positive animals were observed. The epidemiological analysis based on the quantitative virological outcomes could provide more information on the efficacy of oral vaccination and dynamics of CSF in the wild boar population, which will help to improve the implementation of control measures for CSF in countries such as Japan and neighboring countries.
  • Marina Gulyaeva, Falk Huettmann, Alexander Shestopalov, Masatoshi Okamatsu, Keita Matsuno, Duc-Huy Chu, Yoshihiro Sakoda, Alexandra Glushchenko, Elaina Milton, Eric Bortz
    Scientific reports 11 (1) 3758 - 3758 2021/02/08
  • Shohei Ogata, Wessam Mohamed Ahmed Mohamed, Kodai Kusakisako, May June Thu, Yongjin Qiu, Mohamed Abdallah Mohamed Moustafa, Keita Matsuno, Ken Katakura, Nariaki Nonaka, Ryo Nakao
    Microorganisms 9 (2) 2021/02/08 
    Members of the genus Spiroplasma are Gram-positive bacteria without cell walls. Some Spiroplasma species can cause disease in arthropods such as bees, whereas others provide their host with resistance to pathogens. Ticks also harbour Spiroplasma, but their role has not been elucidated yet. Here, the infection status and genetic diversity of Spiroplasma in ticks were investigated using samples collected from different geographic regions in Japan. A total of 712 ticks were tested for Spiroplasma infection by PCR targeting 16S rDNA, and Spiroplasma species were genetically characterized based on 16S rDNA, ITS, dnaA, and rpoB gene sequences. A total of 109 samples originating from eight tick species were positive for Spiroplasma infection, with infection rates ranging from 0% to 84% depending on the species. A linear mixed model indicated that tick species was the primary factor associated with Spiroplasma infection. Moreover, certain Spiroplasma alleles that are highly adapted to specific tick species may explain the high infection rates in Ixodes ovatus and Haemaphysalis kitaokai. A comparison of the alleles obtained suggests that horizontal transmission between tick species may not be a frequent event. These findings provide clues to understand the transmission cycle of Spiroplasma species in wild tick populations and their roles in host ticks.
  • Ryo Nakao, Kohei Shinjo, Tomoki Sakiyama, Shohei Ogata, Kodai Kusakisako, Gohta Kinoshita, Doaa Naguib, Elisha Chatanga, Wessam Mohamed Ahmed Mohamed, Mohamed Abdallah Mohamed Moustafa, Keita Matsuno, Takuya Ito, Nariaki Nonaka, Mariko Sashika, Toshio Tsubota, Michito Shimozuru
    Parasitology international 80 102209 - 102209 2021/02 
    The tick Amblyomma testudinarium Koch, 1844 (Acari: Ixodidae) is known as a vector of several pathogens such as Rickettsia tamurae and severe fever with thrombocytopenia syndrome (SFTS) virus. This tick species is present in many Asian countries, including Japan, where its distribution is limited to the warm areas of Kanto region and the southwestern region. The present study reports the recovery of a partially engorged A. testudinarium from a wild brown bear captured in Shari town, Hokkaido. In addition to morphological identification, the specimen was genetically characterized by the complete mitochondrial genome sequencing. The results showed that the length of the obtained mitogenome is 14,835 bp that encodes 13 protein-coding, two ribosomal RNA (rRNA) (12S and 16S), and 22 transfer RNA genes with two non-coding control regions. The phylogenetic analysis indicated that our sample clustered with A. testudinarium from Nara, Japan, but separated from A. testudinarium from China. Although the introduction of the tick through livestock transportation cannot be ruled out, the detection of A. testudinarium in Hokkaido prefecture, which is separated from the main island where A. testudinarium is present in the south, may suggest the introduction by migratory birds. This study provides important insights on the distribution and host range of A. testudinarium. This will be useful for the future taxonomic analysis of ticks based on the complete mitogenome sequencing. To our knowledge, this is the northernmost detection point of the tropical tick A. testudinarium.
  • Augustin T Twabela, Lam Thanh Nguyen, Justin Masumu, Patrick Mpoyo, Serge Mpiana, Julienne Sumbu, Masatoshi Okamatsu, Keita Matsuno, Norikazu Isoda, Bianca Zecchin, Isabella Monne, Yoshihiro Sakoda
    Viruses 13 (2) 2021/01/20 
    Newcastle disease (ND) is a highly transmissible and devastating disease that affects poultry and wild birds worldwide. Comprehensive knowledge regarding the characteristics and epidemiological factors of the ND virus (NDV) is critical for the control and prevention of ND. Effective vaccinations can prevent and control the spread of the NDV in poultry populations. For decades, the Democratic Republic of the Congo (DRC) has reported the impacts of ND on commercial and traditional poultry farming systems. The reports were preliminary clinical observations, and few cases were confirmed in the laboratory. However, data on the phylogenetic, genetic, and virological characteristics of NDVs circulating in the DRC are not available. In this study, the whole-genome sequences of three NDV isolates obtained using the next-generation sequencing method revealed two isolates that were a new variant of NDV, and one isolate that was clustered in the subgenotype VII.2. All DRC isolates were velogenic and were antigenically closely related to the vaccine strains. Our findings reveal that despite the circulation of the new variant, ND can be controlled in the DRC using the current vaccine. However, epidemiological studies should be conducted to elucidate the endemicity of the disease so that better control strategies can be implemented.
  • Samuel Kelava, Ben J Mans, Renfu Shao, Mohamed Abdallah Mohamed Moustafa, Keita Matsuno, Ai Takano, Hiroki Kawabata, Kozue Sato, Hiromi Fujita, Chen Ze, Olivier Plantard, Sandor Hornok, Shan Gao, Dayana Barker, Stephen C Barker, Ryo Nakao
    Ticks and tick-borne diseases 12 (1) 101577 - 101577 2021/01 
    The evolution and phylogenetic relationships of the ticks at both the family and genus levels are contested. The genus Amblyomma and its subgenera are in a state of flux; moreover, the relationships among the three tick families are controversial due to conflicting phylogenetic support for different arrangements of the three families of living ticks. With 18 newly sequenced mitochondrial (mt) genomes of ticks included, we executed the largest mt genome phylogenetic study of ticks so far. Phylogenetic trees were inferred from one sea spider mt genome, one horseshoe crab, five mite mt genomes and 146 tick mt genomes from 120 species: 153 mt genomes in total. Sixteen phylogenetic trees were inferred from 10 datasets using both maximum likelihood and Bayesian inference methods. We describe the first novel mt gene-arrangement for the metastriate Ixodidae in Amblyomma (Africaniella) transversale. Also, three unusual partial 16S rRNA gene inserts were found in the mt genome of Haemaphysalis (Alloceraea) kitaokai: we consider the possible role of past genome translocation events in the formation of these inserts. Our phylogenies revealed evidence that: (i) the genus Amblyomma is polyphyletic with respect to Amblyomma (Africaniella) transversale; (ii) the subgenus Aponomma is apparently embedded in the genus Amblyomma; (iii) Haemaphysalis (Segalia) parva and Haemaphysalis (Alloceraea) kitaokai form a clade to the exclusion of other Haemaphysalis species; and (iv) the phylogenetic position of the family Nuttalliellidae is unstable among phylogenies from different datasets.
  • Crystal A Mendoza, Satoko Yamaoka, Yoshimi Tsuda, Keita Matsuno, Carla M Weisend, Hideki Ebihara
    Antiviral research 185 104993 - 104993 2021/01 
    Severe fever with thrombocytopenia syndrome virus (SFTSV) and Heartland virus (HRTV) cause viral hemorrhagic fever-like illnesses in humans due to an aberrant host inflammatory response, which contributes to pathogenesis. Here, we established two separate minigenome (MG) systems based on the M-segment of SFTSV and HRTV. Following characterization of both systems for SFTSV and HRTV, we used them as a platform to screen potential compounds that inhibit viral RNA synthesis. We demonstrated that the NF-κB inhibitor, SC75741, reduces viral RNA synthesis of SFTSV and HRTV using our MG platform and validated these results using infectious SFTSV and HRTV. These results may lead to the use of MG systems as potential screening systems for the identification of antiviral compounds and yield novel insights into host-factors that could play role in bandavirus transcription and replication.
  • Hirotaka Hayashi, Norikazu Isoda, Enkhbold Bazarragchaa, Naoki Nomura, Keita Matsuno, Masatoshi Okamatsu, Hiroshi Kida, Yoshihiro Sakoda
    Vaccines 8 (4) 2020/12/16 
    H4 influenza viruses have been isolated from birds across the world. In recent years, an H4 influenza virus infection has been confirmed in pigs. Pigs play an important role in the transmission of influenza viruses to human hosts. Therefore, it is important to develop a new vaccine in the case of an H4 influenza virus infection in humans, considering that this virus has a different antigenicity from seasonal human influenza viruses. In this study, after selecting vaccine candidate strains based on their antigenic relation to one of the pig isolates, A/swine/Missouri/A01727926/2015 (H4N6) (MO/15), an inactivated whole-particle vaccine was prepared from A/swan/Hokkaido/481102/2017 (H4N6). This vaccine showed high immunogenicity in mice, and the antibody induced by the vaccine showed high cross-reactivity to the MO/15 virus. This vaccine induced sufficient neutralizing antibodies and mitigated the effects of an MO/15 infection in a mouse model. This study is the first to suggest that an inactivated whole-particle vaccine prepared from an influenza virus isolated from wild birds is an effective countermeasure in case of a future influenza pandemic caused by the H4 influenza virus.
  • Augustin Twabela, Masatoshi Okamatsu, Keita Matsuno, Norikazu Isoda, Yoshihiro Sakoda
    Viruses 12 (12) 2020/12/08 
    Control measures in the case of high pathogenicity avian influenza (HPAI) outbreaks in poultry include culling, surveillance, and biosecurity; wild birds in captivity may also be culled, although some rare bird species should be rescued for conservation. In this study, two anti-influenza drugs, baloxavir marboxil (BXM) and peramivir (PR), used in humans, were examined in treating HPAI in birds, using chickens as a model. Chickens were infected with H5N6 HPAI virus and were treated immediately or 24 h from challenge with 20 mg/kg BXM or PR twice a day for five days. As per our findings, BXM significantly reduced virus replication in organs and provided full protection to chickens compared with that induced by PR. In the 24-h-delayed treatment, neither drug completely inhibited virus replication nor ensured the survival of infected chickens. A single administration of 2.5 mg/kg of BXM was determined as the minimum dose required to fully protect chickens from HPAI virus; the concentration of baloxavir acid, the active form of BXM, in chicken blood at this dose was sufficient for a 48 h antiviral effect post-administration. Thus, these data can be a starting point for the use of BXM and PR in treating captive wild birds infected with HPAI virus.
  • Marina Gulyaeva, Falk Huettmann, Alexander Shestopalov, Masatoshi Okamatsu, Keita Matsuno, Duc-Huy Chu, Yoshihiro Sakoda, Alexandra Glushchenko, Elaina Milton, Eric Bortz
    Scientific reports 10 (1) 16817 - 16817 2020/10/08 
    Avian Influenza (AI) is a complex but still poorly understood disease; specifically when it comes to reservoirs, co-infections, connectedness and wider landscape perspectives. Low pathogenic (Low-path LP) AI in chickens caused by less virulent strains of AI viruses (AIVs)-when compared with highly pathogenic AIVs (HPAIVs)-are not even well-described yet or known how they contribute to wider AI and immune system issues. Co-circulation of LPAIVs with HPAIVs suggests their interactions in their ecological aspects. Here we show for the Pacific Rim an international approach how to data mine and model-predict LP AI and its ecological niche with machine learning and open access data sets and geographic information systems (GIS) on a 5 km pixel size for best-possible inference. This is based on the best-available data on the issue (~ 40,827 records of lab-analyzed field data from Japan, Russia, Vietnam, Mongolia, Alaska and Influenza Research Database (IRD) and U.S. Department of Agriculture (USDA) database sets, as well as 19 GIS data layers). We sampled 157 hosts and 110 low-path AIVs with 32 species as drivers. The prevalence across low-path AIV subtypes is dominated by Muscovy ducks, Mallards, Whistling Swans and gulls also emphasizing industrial impacts for the human-dominated wildlife contact zone. This investigation sets a good precedent for the study of reservoirs, big data mining, predictions and subsequent outbreaks of HPAI and other pandemics.
  • 北海道斜里町においてエゾヒグマより採集されたタカサゴキララマダニの一例
    下鶴 倫人, 新庄 康平, 崎山 智樹, 小方 昌平, 草木迫 浩大, 木下 豪太, Mohamed Wessam Mohamed Ahmed, Moustafa Mohamed Abdallah Mohamed, 松野 啓太, 伊東 拓也, 野中 成晃, 佐鹿 万里子, 坪田 敏男, 中尾 亮
    日本獣医学会学術集会講演要旨集 (公社)日本獣医学会 163回 327 - 327 1347-8621 2020/10
  • 2016-2017年のベトナム南部での疫学的研究から明らかになった、鳥インフルエンザウイルスの新たなホットスポットの意義(The implication of a new hot spot of avian influenza based on epidemiological study in southern Vietnam in 2016-2017)
    Le Trung Kien, 磯田 典和, Nguyen Thanh Lam, Chu Duc-Huy, Tien Tien Ngoc, 松野 啓太, 岡松 正敏, 喜田 宏, 迫田 義博, 北海道大人獣共通感染症リサーチセンター/国際協働ユニット
    日本獣医学会学術集会講演要旨集 163回 232 - 232 1347-8621 2020/10
  • コンゴ民主共和国で分離された新たなニューカッスル病ウイルスの性状(Characterization of novel Newcastle disease viruses isolated in the Democratic Republic of Congo)
    Twabela Augustin, Mpoyo Patrick, Masumu Justin, Zecchin Bianca, Monne Isabela, 岡松 正敏, 松野 啓太, 迫田 義博, 北海道大人獣共通感染症リサーチセンター/国際協働ユニット
    日本獣医学会学術集会講演要旨集 163回 233 - 233 1347-8621 2020/10
  • ウイルス学的解析および疫学的解析を用いた北海道十勝地方における牛ウイルス性下痢ウイルスの伝播経路解明
    廣瀬 静香, 野津 昂亮, 松野 啓太, 岡松 正敏, 川本 恵子, 磯田 典和, 迫田 義博
    日本獣医学会学術集会講演要旨集 (公社)日本獣医学会 163回 236 - 236 1347-8621 2020/10
  • 日本の岐阜県にてイノシシから採取した血中古典的ブタ熱ウイルス抗原と抗体に関する定量分析(Quantitative analysis of antigen and antibody of classical swine fever virus in wild boar sera collected in Gifu prefecture, Japan)
    Enkhbold Bazarragchaa, 金 琢洙, 哲翁 まどか, 磯田 典和, 松野 啓太, 迫田 義博, 北海道大人獣共通感染症リサーチセンター/国際協働ユニット
    日本獣医学会学術集会講演要旨集 163回 243 - 243 1347-8621 2020/10
  • Ankhanbaatar Ulaankhuu, Enkhbold Bazarragchaa, Masatoshi Okamatsu, Takahiro Hiono, Khishgee Bodisaikhan, Tsolmon Amartuvshin, Jargalsaikhan Tserenjav, Tsogtbaatar Urangoo, Khanui Buyantogtokh, Keita Matsuno, Takanari Hattori, Tatsunari Kondoh, Masahiro Sato, Yoshihiro Takadate, Shiho Torii, Mao Isono, Kosuke Okuya, Takeshi Saito, Nodoka Kasajima, Yurie Kida, Junki Maruyama, Manabu Igarashi, Ayato Takada, Hiroshi Kida, Damdinjav Batchuluun, Yoshihiro Sakoda
    Virus genes 56 (4) 472 - 479 2020/08 [Refereed][Not invited]
     
    The circulation of highly pathogenic avian influenza viruses (HPAIVs) of various subtypes (e.g., H5N1, H5N6, H5N8, and H7N9) in poultry remains a global concern for animal and public health. Migratory waterfowls play important roles in the transmission of these viruses across countries. To monitor virus spread by wild birds, active surveillance for avian influenza in migratory waterfowl was conducted in Mongolia from 2015 to 2019. In total, 5000 fecal samples were collected from lakesides in central Mongolia, and 167 influenza A viruses were isolated. Two H5N3, four H7N3, and two H7N7 viruses were characterized in this study. The amino acid sequence at hemagglutinin (HA) cleavage site of those isolates suggested low pathogenicity in chickens. Phylogenetic analysis revealed that all H5 and H7 viruses were closely related to recent H5 and H7 low pathogenic avian influenza viruses (LPAIVs) isolated from wild birds in Asia and Europe. Antigenicity of H7Nx was similar to those of typical non-pathogenic avian influenza viruses (AIVs). While HPAIVs or A/Anhui/1/2013 (H7N9)-related LPAIVs were not detected in migratory waterfowl in Mongolia, sporadic introductions of AIVs including H5 and H7 viruses into Mongolia through the wild bird migration were identified. Thus, continued monitoring of H5 and H7 AIVs in both domestic and wild birds is needed for the early detection of HPAIVs spread into the country.
  • Hirotaka Hayashi, Masatoshi Okamatsu, Honami Ogasawara, Naoko Tsugawa, Norikazu Isoda, Keita Matsuno, Yoshihiro Sakoda
    Nutrients 12 (7) 2020/07/05 
    Vitamin D is a fat-soluble vitamin that is metabolized by the liver into 25-hydroxyvitamin D [25(OH)D] and then by the kidney into 1,25-dihydroxyvitamin D [1,25(OH)2D], which activates the vitamin D receptor expressed in various cells, including immune cells, for an overall immunostimulatory effect. Here, to investigate whether oral supplementation of 25-hydroxyvitamin D3 [25(OH)D3], a major form of vitamin D metabolite 25(OH)D, has a prophylactic effect on influenza A virus infection, mice were fed a diet containing a high dose of 25(OH)D3 and were challenged with the influenza virus. In the lungs of 25(OH)D3-fed mice, the viral titers were significantly lower than in the lungs of standardly fed mice. Additionally, the proinflammatory cytokines IL-5 and IFN-γ were significantly downregulated after viral infection in 25(OH)D3-fed mice, while anti-inflammatory cytokines were not significantly upregulated. These results indicate that 25(OH)D3 suppresses the production of inflammatory cytokines and reduces virus replication and clinical manifestations of influenza virus infection in a mouse model.
  • Cong Thanh Nguyen, Saori Suzuki, Yasushi Itoh, Hirohito Ishigaki, Misako Nakayama, Kaori Hayashi, Keita Matsuno, Masatoshi Okamatsu, Yoshihiro Sakoda, Hiroshi Kida, Kazumasa Ogasawara
    Antimicrobial agents and chemotherapy 64 (7) 2020/06/23 [Refereed][Not invited]
     
    Attention has been paid to H5N6 highly pathogenic avian influenza virus (HPAIV) because of its heavy burden on the poultry industry and human mortality. Since an influenza A virus carrying N6 neuraminidase (NA) has never spread in humans, the potential for H5N6 HPAIV to cause disease in humans and the efficacy of antiviral drugs against the virus need to be urgently assessed. We used nonhuman primates to elucidate the pathogenesis of H5N6 HPAIV as well as to determine the efficacy of antiviral drugs against the virus. H5N6 HPAIV infection led to high fever in cynomolgus macaques. The lung injury caused by the virus was severe, with diffuse alveolar damage and neutrophil infiltration. In addition, an increase in interferon alpha (IFN-α) showed an inverse correlation with virus titers during the infection process. Oseltamivir was effective for reducing H5N6 HPAIV propagation, and continuous treatment with peramivir reduced virus propagation and the severity of symptoms in the early stage. This study also showed pathologically severe lung injury states in cynomolgus macaques infected with H5N6 HPAIV, even in those that received early antiviral drug treatments, indicating the need for close monitoring and further studies on virus pathogenicity and new antiviral therapies.
  • Lam Thanh Nguyen, Mark A Stevenson, Simon M Firestone, Leslie D Sims, Duc Huy Chu, Long Van Nguyen, Tien Ngoc Nguyen, Kien Trung Le, Norikazu Isoda, Keita Matsuno, Masatoshi Okamatsu, Hiroshi Kida, Yoshihiro Sakoda
    Preventive veterinary medicine 178 104678 - 104678 2020/05 [Refereed][Not invited]
     
    The aim of this study was to describe the spatiotemporal distribution of H5 HPAI outbreak reports for the period 2014-2017 and to identify factors associated with H5 HPAI outbreak reports. Throughout the study period, a total of 139 outbreaks of H5 HPAI in poultry were reported, due to either H5N1 (96 outbreaks) or H5N6 (43 outbreaks) subtype viruses. H5N1 HPAI outbreaks occurred in all areas of Vietnam while H5N6 HPAI outbreaks were only reported in the northern and central provinces. We counted the number of H5N1 and H5N6 outbreak report-positive districts per province over the four-year study period and calculated the provincial-level standardized morbidity ratio for H5N1 and H5N6 outbreak reports as the observed number of positive districts divided by the expected number. A mixed-effects, zero-inflated Poisson regression model was developed to identify risk factors for outbreak reports of each H5N1 and H5N6 subtype virus. Spatially correlated and uncorrelated random effects terms were included in this model to identify areas of the country where outbreak reports occurred after known risk factors had been accounted-for. The presence of an outbreak report in a province in the previous 6-12 months increased the provincial level H5N1 outbreak report risk by a factor of 2.42 (95% Bayesian credible interval [CrI] 1.27-4.60) while 1000 bird increases in the density of chickens decreased provincial level H5N6 outbreak report risk by a factor of 0.65 (95% CrI 0.38 to 0.97). We document distinctly different patterns in the spatial and temporal distribution of H5N1 and H5N6 outbreak reports. Most of the variation in H5N1 report risk was accounted-for by the fixed effects included in the zero-inflated Poisson model. In contrast, the amount of unaccounted-for risk in the H5N6 model was substantially greater than the H5N1 model. For H5N6 we recommend that targeted investigations should be carried out in provinces with relatively large spatially correlated random effect terms to identify likely determinants of disease. Similarly, investigations should be carried out in provinces with relatively low spatially correlated random effect terms to identify protective factors for disease and/or reasons for failure to report.
  • Yuto Kikutani, Masatoshi Okamatsu, Shoko Nishihara, Sayaka Takase-Yoden, Takahiro Hiono, Robert P de Vries, Ryan McBride, Keita Matsuno, Hiroshi Kida, Yoshihiro Sakoda
    Microbiology and immunology 64 (4) 304 - 312 2020/04 [Refereed][Not invited]
     
    Avian influenza viruses (AIVs) recognize sialic acid linked α2,3 to galactose (SAα2,3Gal) glycans as receptors. In this study, the interactions between hemagglutinins (HAs) of AIVs and sulfated SAα2,3Gal glycans were analyzed to clarify the molecular basis of interspecies transmission of AIVs from ducks to chickens. It was revealed that E190V and N192D substitutions of the HA increased the recovery of viruses derived from an H6 duck virus isolate, A/duck/Hong Kong/960/1980 (H6N2), in chickens. Recombinant HAs from an H6 chicken virus, A/chicken/Tainan/V156/1999 (H6N1), bound to sulfated SAα2,3Gal glycans, whereas the HAs from an H6 duck virus did not. Binding preference of mutant HAs revealed that an E190V substitution is critical for the recognition of sulfated SAα2,3Gal glycans. These results suggest that the binding of the HA from H6 AIVs to sulfated SAα2,3Gal glycans explains a part of mechanisms of interspecies transmission of AIVs from ducks to chickens.
  • Madoka Tetsuo, Keita Matsuno, Tomokazu Tamura, Takasuke Fukuhara, Taksoo Kim, Masatoshi Okamatsu, Norbert Tautz, Yoshiharu Matsuura, Yoshihiro Sakoda
    Pathogens (Basel, Switzerland) 9 (3) 2020/03/04 [Refereed][Not invited]
     
    A serum neutralization test (SNT) is an essential method for the serological diagnosis of pestivirus infections, including classical swine fever, because of the cross reactivity of antibodies against pestiviruses and the non-quantitative properties of antibodies in an enzyme-linked immunosorbent assay. In conventional SNTs, an immunoperoxidase assay or observation of cytopathic effect after incubation for 3 to 7 days is needed to determine the SNT titer, which requires labor-intensive or time-consuming procedures. Therefore, a new SNT, based on the luciferase system and using classical swine fever virus, bovine viral diarrhea virus, and border disease virus possessing the 11-amino-acid subunit derived from NanoLuc luciferase was developed and evaluated; this approach enabled the rapid and easy determination of the SNT titer using a luminometer. In the new method, SNT titers can be determined tentatively at 2 days post-infection (dpi) and are comparable to those obtained by conventional SNTs at 3 or 4 dpi. In conclusion, the luciferase-based SNT can replace conventional SNTs as a high-throughput antibody test for pestivirus infections.
  • Kien Trung Le, Masatoshi Okamatsu, Lam Thanh Nguyen, Keita Matsuno, Duc-Huy Chu, Tien Ngoc Tien, Tung Thanh Le, Hiroshi Kida, Yoshihiro Sakoda
    Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases 78 104117 - 104117 2020/03 [Refereed][Not invited]
     
    During the annual surveillance of avian influenza viruses (AIVs) in Vietnam in 2018, three H7N7 AIV isolates were identified in domestic ducks in a single flock in Vinh Long province. The present study is the first documented report of H7N7 virus isolates in Vietnam and aimed to characterize these viruses, both genetically and antigenically. Deduced amino acid sequences for the hemagglutinins (HAs) indicated a low pathogenicity of these viruses in chickens. Phylogenetic analysis revealed that the H7 HA genes of these isolates were closely related to each other and belonged to the European-Asian sublineage, together with those of H7N3 viruses isolated from ducks in Cambodia during 2017. They were not genetically related to those of Chinese H7N9 or H7N1 viruses that were previously detected in Vietnam during 2012. Interestingly, the M genes of the two H7N7 virus isolates were phylogenetically classified into distinct groups, suggesting an ongoing reassortment event in domestic ducks because they were isolated from the same flock. These H7N7 viruses exhibited somewhat different antigenic characteristics compared with other representative H7 low pathogenic AIVs. Surprisingly, the antigenicity of Vietnamese H7N7 viruses is similar to Chinese H7N9 highly pathogenic AIV. The findings of this study suggest that H7N7 viruses may be undergoing reassortment and antigenic diversification in poultry flocks in Vietnam. The silent spread of Vietnamese H7N7 viruses in chickens may lead to acquire high pathogenicity in chickens although the zoonotic potential of the viruses seems to be low since these viruses retain typical avian-specific motifs in the receptor-binding site in the HA and there is no mutation related to mammalian adaptation in PB2 gene. Thus, these results highlight the need for continuous and intensive surveillance of avian influenza in Vietnam, targeting not only highly pathogenic AIVs but also low pathogenic viruses.
  • Yukari Itakura, Keita Matsuno, Asako Ito, Markus Gerber, Matthias Liniger, Yuri Fujimoto, Tomokazu Tamura, Ken-Ichiro Kameyama, Masatoshi Okamatsu, Nicolas Ruggli, Hiroshi Kida, Yoshihiro Sakoda
    Virus research 276 197809 - 197809 2020/01/15 [Refereed][Not invited]
     
    Classical swine fever viruses (CSFVs) do typically not show cytopathic effect (CPE) in cell culture, while some strains such as vaccine strain the GPE- induce CPE in the swine kidney-derived CPK-NS cell line cultured in serum-free medium. These latter strains commonly lack Npro-mediated inhibition of type-I interferon (IFN) induction. In order to explore the molecular mechanisms of GPE--induced CPE, we analyzed the cellular pathways involved. In CPK-NS cells infected with the attenuated-vaccine-derived vGPE- strain, both, apoptosis and necroptosis were induced. Necroptosis was type-I IFN-dependent and critical for visible CPE. In contrast, the parental virulent vALD-A76 strain did not induce any of these pathways nor CPE. We used reverse genetics to investigate which viral factors regulate these cell-death pathways. Interestingly, a mutant vGPE- in which the Npro function was restored to inhibit type-I IFN induction did not induce necroptosis nor CPE but still induced apoptosis, while an Npro-mutant vALD-A76 incapable of inhibiting type-I IFN production induced necroptosis and CPE. Although Erns of CSFV is reportedly involved in controlling apoptosis, apoptosis induction by vGPE- or apoptosis inhibition by vALD-A76 were independent of the unique amino acid difference found in Erns of these two strains. Altogether, these results demonstrate that type-I IFN-dependent necroptosis related to non-functional Npro is the main mechanism for CPE induction by vGPE-, and that viral factor(s) other than Erns may induce or inhibit apoptosis in vGPE- or vALD-A76 infected CPK-NS cells, respectively.
  • Augustin T Twabela, Masatoshi Okamatsu, Georges Mbuyi Tshilenge, Serge Mpiana, Justin Masumu, Lam Thanh Nguyen, Keita Matsuno, Isabella Monne, Bianca Zecchin, Yoshihiro Sakoda
    Archives of virology 165 (1) 87 - 96 2020/01 [Refereed][Not invited]
     
    In May 2017, high mortality of chickens and Muscovy ducks due to the H5N8 highly pathogenic avian influenza virus (HPAIV) was reported in the Democratic Republic of Congo (DR Congo). In this study, we assessed the molecular, antigenic, and pathogenic features in poultry of the H5N8 HPAIV from the 2017 Congolese outbreaks. Phylogenetic analysis of the eight viral gene segments revealed that all 12 DR Congo isolates clustered in clade 2.3.4.4B together with other H5N8 HPAIVs isolated in Africa and Eurasia, suggesting a possible common origin of these viruses. Antigenically, a slight difference was observed between the Congolese isolates and a representative virus from group C in the same clade. After intranasal inoculation with a representative DR Congo virus, high pathogenicity was observed in chickens and Muscovy ducks but not in Pekin ducks. Viral replication was higher in chickens than in Muscovy duck and Pekin duck organs; however, neurotropism was pronounced in Muscovy ducks. Our data confirmed the high pathogenicity of the DR Congo virus in chickens and Muscovy ducks, as observed in the field. National awareness and strengthening surveillance in the region are needed to better control HPAIVs.
  • Alexandra V Glushchenko, Tatyana Y Alikina, Kseniya S Yurchenko, Egor V Shekunov, Marina A Gulyaeva, Keita Matsuno, Masatoshi Okamatsu, Marsel R Kabilov, Alexander M Shestopalov
    Microbiology resource announcements 8 (50) 2019/12/12 [Refereed][Not invited]
     
    This work describes the nearly complete genome sequence of Newcastle disease virus (NDV) strain NDV/Novosibirsk/garganey/27/2014, which was isolated from a wild garganey in western Siberia, Russia. The NDV strain was classified as belonging to class II of genotype I and was identified as having recent common ancestry with isolates from wild and domestic birds in China and South Korea.
  • Takara Hajake, Keita Matsuno, Dacquin M Kasumba, Haruka Oda, Moe Kobayashi, Nao Miyata, Madoka Shinji, Amane Kogure, Nodoka Kasajima, Masatoshi Okamatsu, Yoshihiro Sakoda, Hiroki Kato, Takashi Fujita
    International immunology 31 (12) 811 - 821 2019/11/08 [Refereed][Not invited]
     
    Double-stranded RNA (dsRNA) is well characterized as an inducer of anti-viral interferon responses. We previously reported that dsRNA extracted from a specific edible plant possesses an immune-modulating capacity to confer, in mice, resistance against respiratory viruses, including the H1N1 strain of the influenza A virus (IAV). We report here that the systemic immune-activating capacity of the plant-derived dsRNA protected mice from infection by a highly virulent H5N1 strain of the IAV. In addition, subcutaneous inoculation of the dsRNA together with the inactivated virion of the H5N1 strain of the IAV suppressed the lethality of the viral infection as compared with individual inoculation of either dsRNA or HA protein, suggesting its potential usage as a vaccination adjuvant. Moreover, intra-peritoneal inoculation of the dsRNA limited the growth of B16-F10 melanoma cells through the activation of NK cells in murine models. Taken together, this study demonstrated the systemic immune-modulating capacity of a plant-derived dsRNA and its potential for nucleic acid-based clinical applications.
  • Uyangaa Temuujin, Ariunaa Tserendorj, Jumpei Fujiki, Yoshihiro Sakoda, Erdene-Ochir Tseren-Ochir, Masatoshi Okamatsu, Keita Matsuno, Tumenjargal Sharav, Motohiro Horiuchi, Takashi Umemura, Tungalag Chultemdorj
    Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases 73 269 - 275 2019/09 [Refereed][Not invited]
     
    Canine parvovirus type 2 (CPV-2) causes a highly contagious and fatal disease, developing into acute hemorrhagic enteritis and myocarditis, in dogs. CPV-2 has evolved, generating antigenic variants CPV-2a/2b/2c that are globally distributed. However, investigating molecular characterization of CPV-2 among dog populations in Mongolia has been limited. Herein, 42 stool samples were collected from dogs with clinical signs of infection, and conventional PCR assays were employed to detect CPV-2 in 23. Our results indicated that during 2016-2018, the new CPV-2a and 2c subtypes were detected in 34.7% of the samples, and the new CPV-2b subtype was detected in 30.4% of samples. VP2 protein sequence analysis and next-generation sequencing of the complete viral genome confirmed these antigenic types. However, sequence analysis indicated new and unreported mutations, Pro580Thr, and Tyr584His in the CPV-2c subtype. From a PCR-positive sample, CPV-2c was successfully isolated, and we performed an immunofluorescence assay for antigen detection. Additionally, we performed genetic characterization and phylogenetic analysis to investigate genetic diversity among isolates from the region, resulting in high CPV-2 genetic diversity in the Mongolian dog population. Striking similarities were also observed between sequences of the strains isolated from Mongolia and China over a similar time span.
  • 重症熱性血小板減少症候群ウイルスの核タンパク質Nと結合する宿主RNAの機能解明
    水間 奎太, 松野 啓太, 岡松 正敏, 高田 礼人, 迫田 義博
    日本獣医学会学術集会講演要旨集 (公社)日本獣医学会 162回 390 - 390 1347-8621 2019/08
  • ベトナムで初単離されたH7N7低病原性鳥インフルエンザウイルスの遺伝学的性状および抗原性の解析(Genetic and antigenic characterization of H7N7 low pathogenic avian influenza viruses firstly isolated in Vietnam)
    Le Trung Kien, Nguyen Thanh Lam, Chu Duc-Huy, Nguyen Tien Ngoc, Nguyen Long Van, Tien Tien Ngoc, 松野 啓太, 岡松 正敏, 喜田 宏, 迫田 義博
    日本獣医学会学術集会講演要旨集 162回 392 - 392 1347-8621 2019/08
  • 鶏の高病原性鳥インフルエンザウイルス感染に対する抗ウイルス薬の作用(Effect of antiviral drugs against highly pathogenic avian influenza virus infection in chickens)
    Augustin T. Twabela, 岡松 正敏, 松野 啓太, 迫田 義博
    日本獣医学会学術集会講演要旨集 162回 392 - 392 1347-8621 2019/08
  • 発光タグHiBiTをレポーターとして用いた遺伝子組換えウイルスによる簡便なペスチウイルス抗体測定法の確立
    哲翁 まどか, 松野 啓太, 田村 友和, 福原 崇介, 松浦 善治, 岡松 正敏, 迫田 義博
    日本獣医学会学術集会講演要旨集 (公社)日本獣医学会 162回 393 - 393 1347-8621 2019/08
  • 海外から持ち込まれた携帯品非加熱家きん畜産物から分離されたH7N3亜型高病原性鳥インフルエンザウイルスの性状解析
    柴田 明弘, 原田 理恵子, 岡松 正敏, 松野 啓太, 有田 知子, 鈴木 康司, 白倉 雅之, 小田切 孝人, 竹前 喜洋, 内田 裕子, 西藤 岳彦, 迫田 義博, 尾坂 優之
    日本獣医学会学術集会講演要旨集 (公社)日本獣医学会 162回 395 - 395 1347-8621 2019/08
  • マダニ中のフレボウイルスの遺伝子系統解析に基づく性状推定
    松野 啓太, 中尾 亮, 梶原 将大, 下田 宙, 海老原 秀喜, 高田 礼人, 前田 健, 岡松 正敏, 迫田 義博
    日本獣医学会学術集会講演要旨集 (公社)日本獣医学会 162回 400 - 400 1347-8621 2019/08
  • Abulikemu Abudurexiti, Scott Adkins, Daniela Alioto, Sergey V Alkhovsky, Tatjana Avšič-Županc, Matthew J Ballinger, Dennis A Bente, Martin Beer, Éric Bergeron, Carol D Blair, Thomas Briese, Michael J Buchmeier, Felicity J Burt, Charles H Calisher, Chénchén Cháng, Rémi N Charrel, Il Ryong Choi, J Christopher S Clegg, Juan Carlos de la Torre, Xavier de Lamballerie, Fēi Dèng, Francesco Di Serio, Michele Digiaro, Michael A Drebot, Xiǎoméi Duàn, Hideki Ebihara, Toufic Elbeaino, Koray Ergünay, Charles F Fulhorst, Aura R Garrison, George Fú Gāo, Jean-Paul J Gonzalez, Martin H Groschup, Stephan Günther, Anne-Lise Haenni, Roy A Hall, Jussi Hepojoki, Roger Hewson, Zhìhóng Hú, Holly R Hughes, Miranda Gilda Jonson, Sandra Junglen, Boris Klempa, Jonas Klingström, Chūn Kòu, Lies Laenen, Amy J Lambert, Stanley A Langevin, Dan Liu, Igor S Lukashevich, Tāo Luò, Chuánwèi Lǚ, Piet Maes, William Marciel de Souza, Marco Marklewitz, Giovanni P Martelli, Keita Matsuno, Nicole Mielke-Ehret, Maria Minutolo, Ali Mirazimi, Abulimiti Moming, Hans-Peter Mühlbach, Rayapati Naidu, Beatriz Navarro, Márcio Roberto Teixeira Nunes, Gustavo Palacios, Anna Papa, Alex Pauvolid-Corrêa, Janusz T Pawęska, Jié Qiáo, Sheli R Radoshitzky, Renato O Resende, Víctor Romanowski, Amadou Alpha Sall, Maria S Salvato, Takahide Sasaya, Shū Shěn, Xiǎohóng Shí, Yukio Shirako, Peter Simmonds, Manuela Sironi, Jin-Won Song, Jessica R Spengler, Mark D Stenglein, Zhèngyuán Sū, Sùróng Sūn, Shuāng Táng, Massimo Turina, Bó Wáng, Chéng Wáng, Huálín Wáng, Jūn Wáng, Tàiyún Wèi, Anna E Whitfield, F Murilo Zerbini, Jìngyuàn Zhāng, Lěi Zhāng, Yànfāng Zhāng, Yong-Zhen Zhang, Yújiāng Zhāng, Xueping Zhou, Lìyǐng Zhū, Jens H Kuhn
    Archives of virology 164 (7) 1949 - 1965 2019/07 [Refereed][Not invited]
     
    In February 2019, following the annual taxon ratification vote, the order Bunyavirales was amended by creation of two new families, four new subfamilies, 11 new genera and 77 new species, merging of two species, and deletion of one species. This article presents the updated taxonomy of the order Bunyavirales now accepted by the International Committee on Taxonomy of Viruses (ICTV).
  • Lam Thanh Nguyen, Simon M Firestone, Mark A Stevenson, Neil D Young, Leslie D Sims, Duc Huy Chu, Tien Ngoc Nguyen, Long Van Nguyen, Tung Thanh Le, Hung Van Nguyen, Hung Nam Nguyen, Tien Ngoc Tien, Tho Dang Nguyen, Bich Ngoc Tran, Keita Matsuno, Masatoshi Okamatsu, Hiroshi Kida, Yoshihiro Sakoda
    Scientific reports 9 (1) 7723 - 7723 2019/05/22 [Refereed][Not invited]
     
    This study aimed to elucidate virus, host and environmental dynamics of Vietnamese H5 highly pathogenic avian influenza viruses (HPAIVs) during 2014-2017. Epidemiologically, H5 HPAIVs were frequently detected in apparently healthy domestic and Muscovy ducks and therefore these are preferred species for H5 HPAIV detection in active surveillance. Virologically, clade 2.3.2.1c and 2.3.4.4 H5 HPAIVs were predominant and exhibited distinct phylogeographic evolution. Clade 2.3.2.1c viruses clustered phylogenetically in North, Central and South regions, whilst clade 2.3.4.4 viruses only detected in North and Central regions formed small groups. These viruses underwent diverse reassortment with existence of at least 12 genotypes and retained typical avian-specific motifs. These H5 HPAIVs exhibited large antigenic distance from progenitor viruses and commercial vaccines currently used in poultry. Bayesian phylodynamic analysis inferred that clade 2.3.2.1c viruses detected during 2014-2017 were likely descended from homologous clade viruses imported to Vietnam previously and/or preexisting Chinese viruses during 2012-2013. Vietnamese clade 2.3.4.4 viruses closely shared genetic traits with contemporary foreign spillovers, suggesting that there existed multiple transboundary virus dispersals to Vietnam. This study provides insights into the evolution of Vietnamese H5 HPAIVs and highlights the necessity of strengthening control measures such as, preventive surveillance and poultry vaccination.
  • Kazuya Takehana, Teruo Kinjyo, Manabu Nemoto, Keita Matsuno
    The Journal of veterinary medical science 81 (3) 504 - 507 0916-7250 2019/03/30 [Refereed][Not invited]
     
    Elephant endotheliotropic herpesvirus type 1 (EEHV1) is the most important causative agent of an acute fatal hemorrhagic disease in Asian elephants (Elephas maximus). We employed loop-mediated isothermal amplification (LAMP) to develop a rapid and simple detection method for EEHV1 in blood. When used to test 21 clinical samples collected in Japan, the EEHV1 assay correctly identified one positive and 20 negative clinical samples. It was observed that when samples were spiked with synthetic DNA plasmids including EEHV1 polymerase gene, the detection limit of the LAMP assay was 101.2 copies/µl and 100-fold higher than that of conventional PCR. These advantages of the LAMP assay for EEHV1 detection may facilitate better veterinary practices for treating elephants suffering from the acute disease.
  • Akihiro Shibata, Rieko Harada, Masatoshi Okamatsu, Keita Matsuno, Tomoko Arita, Yasushi Suzuki, Masayuki Shirakura, Takato Odagiri, Nobuhiro Takemae, Yuko Uchida, Takehiko Saito, Yoshihiro Sakoda, Hiroyuki Osaka
    The Journal of veterinary medical science 81 (3) 444 - 448 0916-7250 2019/03/20 [Refereed][Not invited]
     
    A new reassortant H7N3 avian influenza virus (AIV) was isolated from a duck meat product that was illegally taken on board a passenger flight from China to Japan in March 2018. Sequencing analysis revealed that the H7N3 isolate, A/duck/Japan/AQ-HE30-1/2018 (Dk/HE30-1) (H7N3), was a reassortant highly pathogenic avian influenza virus (HPAIV) that contained the haemagglutinin (HA) gene of Chinese H7N9 HPAIV. Dk/HE30-1 (H7N3) possessed a novel polybasic sequence motif PEVPKRRRTAR/GLF at the HA cleavage site that has never previously been reported in H7 HPAIVs. The HA antigenicity of Dk/HE30-1 (H7N3) slightly differed from that of H7N9 HPAIVs previously reported. These findings will help further our knowledge of the circulation and genetic evolution of emerging AIVs in endemic areas.
  • Keiichi Taniguchi, Yoshinori Ando, Haruaki Nobori, Shinsuke Toba, Takeshi Noshi, Masanori Kobayashi, Makoto Kawai, Ryu Yoshida, Akihiko Sato, Takao Shishido, Akira Naito, Keita Matsuno, Masatoshi Okamatsu, Yoshihiro Sakoda, Hiroshi Kida
    Scientific reports 9 (1) 3466 - 3466 2019/03/05 [Refereed][Not invited]
     
    Human infections with avian-origin influenza A(H7N9) virus represent a serious threat to global health; however, treatment options are limited. Here, we show the inhibitory effects of baloxavir acid (BXA) and its prodrug baloxavir marboxil (BXM), a first-in-class cap-dependent endonuclease inhibitor, against A(H7N9), in vitro and in vivo. In cell culture, BXA at four nanomolar concentration achieved a 1.5-2.8 log reduction in virus titers of A(H7N9), including the NA-R292K mutant virus and highly pathogenic avian influenza viruses, whereas NA inhibitors or favipiravir required approximately 20-fold or higher concentrations to achieve the same levels of reduction. A(H7N9)-specific amino acid polymorphism at position 37, implicated in BXA binding to the PA endonuclease domain, did not impact on BXA susceptibility. In mice, oral administration of BXM at 5 and 50 mg/kg twice a day for 5 days completely protected from a lethal A/Anhui/1/2013 (H7N9) challenge, and reduced virus titers more than 2-3 log in the lungs. Furthermore, the potent therapeutic effects of BXM in mice were still observed when a higher virus dose was administered or treatment was delayed up to 48 hours post infection. These findings support further investigation of BXM for A(H7N9) treatment in humans.
  • Enkhbold Bazarragchaa, Masatoshi Okamatsu, Ankhanbaatar Ulaankhuu, Augustin Tshibwabwa Twabela, Keita Matsuno, Hiroshi Kida, Yoshihiro Sakoda
    Journal of virological methods 265 121 - 125 0166-0934 2019/03 [Refereed][Not invited]
     
    Rapid and accurate diagnosis of influenza virus infection is essential for quick responses for both human and animal health. The Alere™ i Influenza A&B is a novel isothermal nucleic acid amplification kit that can detect and differentiate between influenza A and B viruses in human specimens in approximately 15 min. In the present study, the performance of the Alere™ i Influenza A&B kit was evaluated for its ability to detect avian influenza virus in chickens. The kit was able to detect representative avian influenza virus strains (hemagglutinin subtypes H1-H16, including the recently isolated H5 and H7 highly pathogenic avian influenza viruses), and the detection limit of the kit for these viruses varied between 10-1.4-102.1 50% egg-infective dose per test, which is higher than the analytical sensitivity of the antigen detection immunochromatography kit ESPLINE® A INFLUENZA. In experimentally infected chickens inoculated with a highly pathogenic avian influenza virus strain A/chicken/Hokkaido/002/2016 (H5N6), viral RNA was detected in the tracheal and cloacal swabs. These results indicate that this kit has the potential to be used as a rapid screening test of influenza A virus infection in chickens.
  • May June Thu, Yongjin Qiu, Keita Matsuno, Masahiro Kajihara, Akina Mori-Kajihara, Ryosuke Omori, Naota Monma, Kazuki Chiba, Junji Seto, Mutsuyo Gokuden, Masako Andoh, Hideo Oosako, Ken Katakura, Ayato Takada, Chihiro Sugimoto, Norikazu Isoda, Ryo Nakao
    Scientific reports 9 (1) 1500 - 1500 2019/02/06 [Refereed][Not invited]
     
    Spotted fever group (SFG) rickettsiae are obligate intracellular Gram-negative bacteria mainly associated with ticks. In Japan, several hundred cases of Japanese spotted fever, caused by Rickettsia japonica, are reported annually. Other Rickettsia species are also known to exist in ixodid ticks; however, their phylogenetic position and pathogenic potential are poorly understood. We conducted a nationwide cross-sectional survey on questing ticks to understand the overall diversity of SFG rickettsiae in Japan. Out of 2,189 individuals (19 tick species in 4 genera), 373 (17.0%) samples were positive for Rickettsia spp. as ascertained by real-time PCR amplification of the citrate synthase gene (gltA). Conventional PCR and sequencing analyses of gltA indicated the presence of 15 different genotypes of SFG rickettsiae. Based on the analysis of five additional genes, we characterised five Rickettsia species; R. asiatica, R. helvetica, R. monacensis (formerly reported as Rickettsia sp. In56 in Japan), R. tamurae, and Candidatus R. tarasevichiae and several unclassified SFG rickettsiae. We also found a strong association between rickettsial genotypes and their host tick species, while there was little association between rickettsial genotypes and their geographical origins. These observations suggested that most of the SFG rickettsiae have a limited host range and are maintained in certain tick species in the natural environment.
  • Shiho Torii, Keita Matsuno, Yongjin Qiu, Akina Mori-Kajihara, Masahiro Kajihara, Ryo Nakao, Naganori Nao, Katsunori Okazaki, Mariko Sashika, Takahiro Hiono, Masatoshi Okamatsu, Yoshihiro Sakoda, Hideki Ebihara, Ayato Takada, Hirofumi Sawa
    Ticks and tick-borne diseases 10 (2) 328 - 335 1877-959X 2019/02 [Refereed][Not invited]
     
    Recent discoveries of tick-borne pathogens have raised public health concerns on tick-borne infectious diseases and emphasize the need to assess potential risks of unrecognized tick-borne pathogens. First, to determine the existence of tick-borne phleboviruses (TBPVs), genetic surveillance of phleboviruses in ticks was conducted mainly in Hokkaido, the northernmost island in Japan from 2013 to 2015. Genes of two TBPVs, previously reported as Mukawa virus (MKWV) and a newly identified relative of MKWV, Kuriyama virus (KURV), were detected and the viruses were isolated from Ixodes persulcatus collected in Hokkaido, but not in I. persulcatus collected from other areas of Japan. These viruses were phylogenetically and antigenically similar to each other. Next, to investigate the infection of MKWV in mammals, serum samples from wildlife captured in Hokkaido from 2007 to 2011 were used for serological screening. Neutralizing antibodies against MKWV were detected in both Yezo-deer (Cervus nippon yesoensis) (2/50) and raccoons (Procyon lotor) (16/64). However, no infectious MKWV was recovered from laboratory mice in experimental infections, though viral RNAs were detected in their tissues. Thus, MKWV and KURV may maintain tick-mammalian life cycles in Hokkaido, suggesting their potential as causative agents of tick-borne diseases in mammals.
  • Haruhiko Fujihira, Katsuaki Usami, Keita Matsuno, Hideyuki Takeuchi, Kaori Denda-Nagai, Jun-Ichi Furukawa, Yasuro Shinohara, Ayato Takada, Yoshihiro Kawaoka, Tatsuro Irimura
    Scientific Reports 8 (1) 5495  2045-2322 2018/12/01 [Refereed][Not invited]
     
    Ebolaviruses comprises 5 species that exert varying degrees of mortality/infectivity in humans with Reston ebolaviruses (REBOV) showing the lowest and Zaire ebolaviruses (ZEBOV) showing the highest. However, the molecular basis of this differential mortality/infectivity remains unclear. Here, we report that the structural features of ebolavirus envelope glycoproteins (GPS) and one of their counter receptors, macrophage galactose-Type calcium-Type lectin (MGL/CD301), play crucial roles in determining viral infectivity. The low infectivity of REBOV mediated by the interaction between GPS and MGL/CD301 dramatically increased when the N-Terminal 18 amino acids (33rd through 50th) of GPS were replaced with that of ZEBOV. Furthermore, structural analysis of glycans of GPS revealed that N-glycans were more extended in REBOV than in ZEBOV. N-glycan extension was reversed by the replacement of aforementioned N-Terminal 18 amino acid residues. Therefore, these data strongly suggest that extended N-glycans on GPS reduce MGL/CD301-mediated viral infectivity by hindering the interaction between GPS and MGL/CD301 preferentially binds O-glycans.
  • Akihiro Shibata, Masatoshi Okamatsu, Riho Sumiyoshi, Keita Matsuno, Zu-Jyun Wang, Hiroshi Kida, Hiroyuki Osaka, Yoshihiro Sakoda
    Virology 524 10 - 17 0042-6822 2018/11 [Refereed][Not invited]
     
    H7N9 highly and low pathogenic avian influenza viruses (HPAIV and LPAIV, respectively) have been isolated from duck meat products that were brought illegally into Japan by flight passengers in their hand luggage. These H7N9 virus isolates were phylogenetically closely related to those prevailing in China. Antigenic analysis revealed that the hemagglutinin of the H7N9 HPAIV isolate was slightly different from those of the H7N9 LPAIV and older H7 strains. These meat products contaminated with AIVs repeatedly brought into Japan lead to increased risks of poultry and public health. Continuous border disease control based on the detection and culling of infected poultry and meat products is, thus, essential for the prevention of introduction and spread of AIVs.
  • Keita Matsuno, Noriyuki Nonoue, Ayako Noda, Nodoka Kasajima, Keita Noguchi, Ai Takano, Hiroshi Shimoda, Yasuko Orba, Mieko Muramatsu, Yoshihiro Sakoda, Ayato Takada, Shinji Minami, Yumi Une, Shigeru Morikawa, Ken Maeda
    Emerging infectious diseases 24 (9) 1726 - 1729 1080-6040 2018/09 [Refereed][Not invited]
     
    Two captive cheetahs from a zoo in Japan died of a severe fever with thrombocytopenia syndrome-like illness. Severe fever with thrombocytopenia syndrome virus, an endemic tickborne phlebovirus, was detected systemically with secretion of infectious viruses into the saliva. These cases highlight the risk for exposure of captive animals to endemic arthropodborne pathogens.
  • Zu-Jyun Wang, Yuto Kikutani, Lam Thanh Nguyen, Takahiro Hiono, Keita Matsuno, Masatoshi Okamatsu, Scott Krauss, Richard Webby, Youn-Jeong Lee, Hiroshi Kida, Yoshihiro Sakoda
    Virus genes 54 (4) 543 - 549 0920-8569 2018/08 [Refereed][Not invited]
     
    Among 16 haemagglutinin (HA) subtypes of avian influenza viruses (AIVs), H13 AIVs have rarely been isolated in wild waterfowl. H13 AIVs cause asymptomatic infection and are maintained mainly in gull and tern populations; however, the recorded antigenic information relating to the viruses has been limited. In this study, 2 H13 AIVs, A/duck/Hokkaido/W345/2012 (H13N2) and A/duck/Hokkaido/WZ68/2012 (H13N2), isolated from the same area in the same year in our surveillance, were genetically and antigenically analyzed with 10 representative H13 strains including a prototype strain, A/gull/Maryland/704/1977 (H13N6). The HA genes of H13 AIVs were phylogenetically divided into 3 groups (I, II, and III). A/duck/Hokkaido/W345/2012 (H13N2) was genetically classified into Group III. This virus was distinct from a prototype strain, A/gull/Maryland/704/1977 (H13N6), and the virus, A/duck/Hokkaido/WZ68/2012 (H13N2), both belonging to Group I. Antigenic analysis indicated that the viruses of Group I were antigenically closely related to those of Group II, but distinct from those of Group III, including A/duck/Hokkaido/W345/2012 (H13N2). In summary, our study indicates that H13 AIVs have undergone antigenic diversification in nature.
  • Keita Matsuno, Masahiro Kajihara, Ryo Nakao, Naganori Nao, Akina Mori-Kajihara, Mieko Muramatsu, Yongjin Qiu, Shiho Torii, Manabu Igarashi, Nodoka Kasajima, Keita Mizuma, Kentaro Yoshii, Hirofumi Sawa, Chihiro Sugimoto, Ayato Takada, Hideki Ebihara
    mSphere 3 (3) 2018/06/27 [Refereed][Not invited]
     
    The recent emergence of novel tick-borne RNA viruses has complicated the epidemiological landscape of tick-borne infectious diseases, posing a significant challenge to public health systems that seek to counteract tick-borne diseases. The identification of two novel tick-borne phleboviruses (TBPVs), severe fever with thrombocytopenia syndrome virus (SFTSV) and Heartland virus (HRTV), as causative agents of severe illness in humans has accelerated the investigation and discoveries of novel TBPVs. In the present study, we isolated a novel TBPV designated Mukawa virus (MKWV) from host-questing Ixodes persulcatus females captured in Japan. Genetic characterization revealed that MKWV is a member of the genus Phlebovirus in the family Phenuiviridae Interestingly, MKWV is genetically distinct from other known TBPVs and shares a most recent common ancestor with mosquito/sandfly-borne (insect-borne) phleboviruses. Despite its genetic similarity to insect-borne phleboviruses, the molecular footprints of its viral proteins and its biological characteristics define MKWV as a tick-borne virus that can be transmitted to mammals. A phylogenetic ancestral-state reconstruction for arthropod vectors of phleboviruses including MKWV based on viral L segment sequences indicated that ticks likely harbored ancestral phleboviruses that evolved into both the tick-borne and MKWV/insect-borne phlebovirus lineages. Overall, our findings suggest that most of the phlebovirus evolution has occurred in hard ticks to generate divergent viruses, which may provide a seminal foundation for understanding the mechanisms underlying the evolution and emergence of pathogenic phleboviruses, such as Rift Valley fever virus and SFTSV/HRTV.IMPORTANCE The emergence of novel tick-borne RNA viruses causing severe illness in humans has complicated the epidemiological landscape of tick-borne diseases, requiring further investigation to safeguard public health. In the present study, we discovered a novel tick-borne phlebovirus from Ixodes persulcatus ticks in Japan. While its viral RNA genome sequences were similar to those of mosquito/sandfly-borne viruses, molecular and biological footprints confirmed that this is a tick-borne virus. The unique evolutionary position of the virus allowed us to estimate the ancestral phlebovirus vector, which was likely a hard tick. Our findings may provide a better understanding of the evolution and emergence of phleboviruses associated with emerging infectious diseases, such as severe fever with thrombocytopenia syndrome (SFTS) and Heartland virus disease.
  • A. Shibata, T. Hiono, H. Fukuhara, R. Sumiyoshi, A. Ohkawara, K. Matsuno, M. Okamatsu, H. Osaka, Y. Sakoda
    Transboundary and Emerging Diseases 65 (2) 465 - 475 1865-1682 2018/04/01 [Refereed][Not invited]
     
    The transportation of poultry and related products for international trade contributes to transboundary pathogen spread and disease outbreaks worldwide. To prevent pathogen incursion through poultry products, many countries have regulations about animal health and poultry product quarantine. However, in Japan, animal products have been illegally introduced into the country in baggage and confiscated at the airport. Lately, the number of illegally imported poultry and the incursion risk of transboundary pathogens through poultry products have been increasing. In this study, we isolated avian influenza viruses (AIVs) from raw poultry products illegally imported to Japan by international passengers. Highly (H5N1 and H5N6) and low (H9N2 and H1N2) pathogenic AIVs were isolated from raw chicken and duck products carried by flight passengers. H5 and H9 isolates were phylogenetically closely related to viruses isolated from poultry in China, and haemagglutinin genes of H5N1 and H5N6 isolates belonged to clades 2.3.2.1c and 2.3.4.4, respectively. Experimental infections of H5 and H9 isolates in chickens and ducks demonstrated pathogenicity and tissue tropism to skeletal muscles. To prevent virus incursion by poultry products, it is important to encourage the phased cleaning based on the disease control and eradication and promote the reduction in contamination risk in animal products.
  • Mizuho Suzuki, Masatoshi Okamatsu, Yuri Fujimoto, Takahiro Hiono, Keita Matsuno, Hiroshi Kida, Yoshihiro Sakoda
    Japanese Journal of Veterinary Research 66 (1) 29 - 41 0047-1917 2018 [Refereed][Not invited]
     
    The H10N8 influenza virus became a threat to public health when cases of fatal infections were identified in China in 2013 and 2014. Thus, genetic and antigenic characterization of H10 influenza viruses and development of an appropriate vaccine are essential to prepare for a future pandemic by H10 influenza viruses. However, current information regarding these properties of H10 influenza viruses circulating in birds is limited. In this study, genetic analysis of H10 influenza viruses revealed that the viruses recently circulating in wild birds in East Asia are genetically close to human H10N8 influenza viruses. Furthermore, the antigenicity of H10 influenza viruses was stable among the viruses circulating in birds. An inactivated vaccine was prepared from A/duck/Mongolia/245/2015 (H10N3), which is genetically and antigenically close to the human H10 influenza viruses. The vaccine induced sufficient neutralizing antibodies against homologous and heterologous viruses in mice. The inactivated vaccine induced protective immunity sufficient to reduce the impact of challenges with A/duck/Hokkaido/W87/2007 (H10N2), which is pathogenic strain in mice. This study demonstrates that the inactivated whole virus particle vaccine prepared from viruses isolated from wild birds would be useful against a future pandemic influenza by H10 influenza viruses.
  • D. -H. Chu, M. A. Stevenson, L. V. Nguyen, N. Isoda, S. M. Firestone, T. N. Nguyen, L. T. Nguyen, K. Matsuno, M. Okamatsu, H. Kida, Y. Sakoda
    TRANSBOUNDARY AND EMERGING DISEASES 64 (6) 1991 - 1999 1865-1674 2017/12 [Refereed][Not invited]
     
    In Vietnam, live bird markets are found in most populated centres, providing the means by which fresh poultry can be purchased by consumers for immediate consumption. Live bird markets are aggregation points for large numbers of poultry, and therefore, it is common for a range of avian influenza viruses to be mixed within live bird markets as a result of different poultry types and species being brought together from different geographical locations. We conducted a cross-sectional study in seven live bird markets in four districts of Thua Thien Hue Province in August and December, 2014. The aims of this study were to (i) document the prevalence of avian influenza in live bird markets (as measured by virus isolation); and (ii) quantify individual bird-, seller- and market-level characteristics that rendered poultry more likely to be positive for avian influenza virus at the time of sale. A questionnaire soliciting details of knowledge, attitude and avian influenza practices was administered to poultry sellers in study markets. At the same time, swabs and faecal samples were collected from individual poultry and submitted for isolation of avian influenza virus. The final data set comprised samples from 1,629 birds from 83 sellers in the seven live bird markets. A total of 113 birds were positive for virus isolation; a prevalence of 6.9 (95% CI 5.8-8.3) avian influenza virus-positive birds per 100 birds submitted for sale. After adjusting for clustering at the market and individual seller levels, none of the explanatory variables solicited in the questionnaire were significantly associated with avian influenza virus isolation positivity. The proportions of variance at the individual market, seller and individual bird levels were 6%, 48% and 46%, respectively. We conclude that the emphasis of avian influenza control efforts in Vietnam should be at the individual seller level as opposed to the market level.
  • Mizuho Suzuki, Masatoshi Okamatsu, Takahiro Hiono, Keita Matsuno, Yoshihiro Sakoda
    JOURNAL OF VETERINARY MEDICAL SCIENCE 79 (11) 1815 - 1821 0916-7250 2017/11 [Refereed][Not invited]
     
    H2N2 influenza virus caused a pandemic starting in 1957 but has not been detected in humans since 1968. Thus, most people are immunologically naive to viruses of the H2 subtype. In contrast, H2 influenza viruses are continually isolated from wild birds, and H2N3 viruses were isolated from pigs in 2006. H2 influenza viruses could cause a pandemic if re-introduced into humans. In the present study, a vaccine against H2 influenza was prepared as an effective control measure against a future human pandemic. A/duck/Hokkaido/162/2013 (H2N1), which showed broad antigenic cross-reactivity, was selected from the candidate H2 influenza viruses recently isolated from wild birds in Asian countries. Sufficient neutralizing antibodies against homologous and heterologous viruses were induced in mice after two subcutaneous injections of the inactivated whole virus particle vaccine. The inactivated vaccine induced protective immunity sufficient to reduce the impact of challenges with A/swine/Missouri/2124514/2006 (H2N3). This study demonstrates that the inactivated whole virus particle vaccine prepared from an influenza virus library would be useful against a future H2 influenza pandemic.
  • Tatsunari Kondoh, Rashid Manzoor, Naganori Nao, Junki Maruyama, Wakako Furuyama, Hiroko Miyamoto, Asako Shigeno, Makoto Kuroda, Keita Matsuno, Daisuke Fujikura, Masahiro Kajihara, Reiko Yoshida, Manabu Igarashi, Ayato Takada
    PLOS ONE 12 (10) e0186450  1932-6203 2017/10 [Refereed][Not invited]
     
    It has been proposed that some non-retroviral RNA virus genes are integrated into vertebrate genomes. Endogenous filovirus-like elements (EFLs) have been discovered in some mammalian genomes. However, their potential roles in ebolavirus infection are unclear. A filovirus VP35-like element (mlEFL35) is found in the little brown bat (Myotis lucifugus) genome. Putative mlEFL35-derived protein (mlEFL35p) contains nearly full-length amino acid sequences corresponding to ebolavirus VP35. Ebola virus VP35 has been shown to bind double-stranded RNA, leading to inhibition of type I interferon (IFN) production, and is also known as a viral polymerase cofactor that is essential for viral RNA transcription/replication. In this study, we transiently expressed mlEFL35p in human kidney cells and investigated its biological functions. We first found that mlEFL35p was coimmunoprecipitated with itself and ebolavirus VP35s but not with the viral nucleoprotein. Then the biological functions of mlEFL35p were analyzed by comparing it to ebolavirus VP35s. We found that the expression of mlEFL35p significantly inhibited human IFN-beta promoter activity as well as VP35s. By contrast, expression of mlEFL35p did not support viral RNA transcription/replication and indeed slightly decrease the reporter gene expression in a minigenome assay. These results suggest that mlEFL35p potentially acts as an IFN antagonist but not a polymerase cofactor.
  • Lam Thanh Nguyen, Tatsuya Nishi, Shintaro Shichinohe, Duc-Huy Chu, Takahiro Hiono, Keita Matsuno, Masatoshi Okamatsu, Hiroshi Kida, Yoshihiro Sakoda
    VIROLOGY 510 252 - 261 0042-6822 2017/10 [Refereed][Not invited]
     
    Vaccination-primed immunity in poultry has been suggested for selection of antigenically drifted highly pathogenic avian influenza viruses (HPAIVs). In this study, we performed two consecutive passage studies of an H5N1 HPAIV in vaccinated chickens, namely, study-I and study-II, to select antigenic variants under immune pressure from the vaccination. In study-I, nine consecutive passages of a wild-type H5N1 HPAIV were carried out in chickens vaccinated with the homologous challenge strain. Antigenically drifted variants with mutations at position 179 in the hemagglutinin (HA) were selected after three passages. Similarly, in study-II, a vaccination-mediated antigenic variant isolated in study-I was used as the vaccine and challenge strain to confirm further antigenic drift after updating the vaccine; after the third passage, additional antigenic variants with a mutation at position 256 in the HA were selected. Thus, our study demonstrated the contribution of vaccination in the selection of antigenic variants of H5 HPAIVs in chickens.
  • Takahiro Hiono, Masatoshi Okamatsu, Keita Matsuno, Atsushi Haga, Ritsuko Iwata, Lam Thanh Nguyen, Mizuho Suzuki, Yuto Kikutani, Hiroshi Kida, Manabu Onuma, Yoshihiro Sakoda
    MICROBIOLOGY AND IMMUNOLOGY 61 (9) 387 - 397 0385-5600 2017/09 [Refereed][Not invited]
     
    On 15 November 2016, a black swan that had died in a zoo in Akita prefecture, northern Japan, was strongly suspected to have highly pathogenic avian influenza (HPAI); an HPAI virus (HPAIV) belonging to the H5N6 subtype was isolated from specimens taken from the bird. After the initial report, 230 cases of HPAI caused by H5N6 viruses from wild birds, captive birds, and domestic poultry farms were reported throughout the country during the winter season. In the present study, 66 H5N6 HPAIVs isolated from northern Japan were further characterized. Phylogenetic analysis of the hemagglutinin gene showed that the H5N6 viruses isolated in northern Japan clustered into Group C of Clade 2.3.4.4 together with other isolates collected in Japan, Korea and Taiwan during the winter season of 2016-2017. The antigenicity of the Japanese H5N6 isolate differed slightly from that of HPAIVs isolated previously in Japan and China. The virus exhibited high pathogenicity and a high replication capacity in chickens, whereas virus growth was slightly lower in ducks compared with that of an H5N8 HPAIV isolate collected in Japan in 2014. Comprehensive analyses of Japanese isolates, including those from central, western, and southern Japan, as well as rapid publication of this information are essential for facilitating greater control of HPAIVs.
  • Lam Thanh Nguyen, Kazunari Nakaishi, Keiko Motojima, Ayako Ohkawara, Erina Minato, Junki Maruyama, Takahiro Hiono, Keita Matsuno, Masatoshi Okamatsu, Takashi Kimura, Ayato Takada, Hiroshi Kida, Yoshihiro Sakoda
    PLOS ONE 12 (8) e0182228  1932-6203 2017/08 [Refereed][Not invited]
     
    Highly pathogenic avian influenza viruses (HPAIVs) of H5 subtype have persistently caused outbreaks in domestic poultry and wild birds worldwide and sporadically infected humans. Rapid and accurate diagnosis is one of the key strategies for the control of H5 HPAIVs. However, the sensitivity of the diagnosis of H5 HPAIVs has gradually reduced due to extensive antigenic variation during their evolution. Particularly, the previously developed immunochromatographic diagnosis kit for H5 viruses, Linjudge Flu A/H5, exhibits reduced detection of H5 HPAIVs isolated in recent years. In the present study, we established a new advanced H5 rapid immunochromatographic detection kit (New Linjudge Flu A/H5) by a combination of two anti-H5 hemagglutinin monoclonal antibodies, A64/1 previously applied in the Linjudge Flu A/H5 and A32/2, a novel monoclonal antibody generated from a clade 2.3.4.4 H5 HPAIV. The new kit broadly detected all classical and recent H5 influenza viruses and showed a higher specificity and sensitivity than the original Linjudge Flu A/H5 with recently circulating H5 HPAIVs. Furthermore, the applicability of the New Linjudge Flu A/H5 was demonstrated by detecting antigens from the swabs and tissue homogenates of naturally infected birds and experimentally infected chickens with H5N6 HPAIVs belonging to the genetic clade 2.3.4.4. Our study, therefore, can provide an effective point-of-care rapid antigen detection kit for the surveillance of H5 avian influenza viruses and as a prompt countermeasure against the current widespread of the clade 2.3.4.4 H5 HPAIVs in domestic and wild birds.
  • Bazarragchaa Enkhbold, Munkhduuren Shatar, Shiho Wakamori, Tomokazu Tamura, Takahiro Hiono, Keita Matsuno, Masatoshi Okamatsu, Takashi Umemura, Batchuluun Damdinjav, Yoshihiro Sakoda
    VIRUS GENES 53 (3) 418 - 425 0920-8569 2017/06 [Refereed][Not invited]
     
    Classical swine fever (CSF), a highly contagious viral disease affecting domestic and wild pigs in many developing countries, is now considered endemic in Mongolia, with 14 recent outbreaks in 2007, 2008, 2011, 2012, 2014, and 2015. For the first time, CSF viruses isolated from these 14 outbreaks were analyzed to assess their molecular epidemiology and pathogenicity in pigs. Based on the nucleotide sequences of their 5'-untranslated region, isolates were phylogenetically classified as either sub-genotypes 2.1b or 2.2, and the 2014 and 2015 isolates, which were classified as 2.1b, were closely related to isolates from China and Korea. In addition, at least three different viruses classified as 2.1b circulated in Mongolia. Experimental infection of the representative isolate in 2014 demonstrated moderate pathogenicity in 4-week-old pigs, with relatively mild clinical signs. Understanding the diversity of circulating CSF viruses gleans insight into disease dynamics and evolution, and may inform the design of effective CSF control strategies in Mongolia.
  • Ayako Ohkawara, Masatoshi Okamatsu, Makoto Ozawa, Duc-Huy Chu, Lam Thanh Nguyen, Takahiro Hiono, Keita Matsuno, Hiroshi Kida, Yoshihiro Sakoda
    MICROBIOLOGY AND IMMUNOLOGY 61 (5) 149 - 158 0385-5600 2017/05 [Refereed][Not invited]
     
    H5 highly pathogenic avian influenza viruses (HPAIV) have spread in both poultry and wild birds since late 2003. Continued circulation of HPAIV in poultry in several regions of the world has led to antigenic drift. In the present study, we analyzed the antigenic properties of H5 HPAIV isolated in Asia using four neutralizing mAbs recognizing hemagglutinin, which were established using A/chicken/Kumamoto/1-7/2014 (H5N8), belonging to clade 2.3.4.4 and also using polyclonal antibodies. Viruses of clades 1.1, 2.3.2.1, 2.3.4, and 2.3.4.4 had different reactivity patterns to the panel of mAbs, thereby indicating that the antigenicity of the viruses of clade 2.3.4.4 were similar but differed from the other clades. In particular, the antigenicity of the viruses of clade 2.3.4.4 differed from those of the viruses of clades 2.3.4 and 2.3.2.1, which suggests that the recent H5 HPAIV have further evolved antigenically divergent. In addition, reactivity of antiserum suggests that the antigenicity of viruses of clade 2.3.4.4 differed slightly among groups A, B, and C. Vaccines are still used in poultry in endemic countries, so the antigenicity of H5 HPAIV should be monitored continually to facilitate control of avian influenza. The panel of mAbs established in the present study will be useful for detecting antigenic drift in the H5 viruses that emerge from the current strains.
  • Akihiro Nakatsukasa, Koji Kuruma, Masatoshi Okamatsu, Takahiro Hiono, Mizuho Suzuki, Keita Matsuno, Hiroshi Kida, Takayoshi Oyamada, Yoshihiro Sakoda
    VACCINE 35 (21) 2855 - 2861 0264-410X 2017/05 [Refereed][Not invited]
     
    Transdermal vaccination using a microneedle (MN) confers enhanced immunity compared with subcutaneous (SC) vaccination. Here we developed a novel dissolving MN patch for the influenza vaccine. The potencies of split virion and whole virus particle (WVP) vaccines prepared from A/Puerto Rico/8/1934 (H1N1) and A/duck/Hokkaido/Vac-3/2007 (H5N1), respectively, were evaluated. MN vaccination induced higher neutralizing antibody responses than SC vaccination in mice. Moreover, MN vaccination with a lower dose of antigens conferred protective immunity against lethal challenges of influenza viruses than SC vaccination in mice. These results suggest that the WVP vaccines administered using MN are an effective combination for influenza vaccine to be further validated in humans. (C) 2017 Elsevier Ltd. All rights reserved.
  • Masatoshi Okamatsu, Makoto Ozawa, Kosuke Soda, Hiroki Takakuwa, Atsushi Haga, Takahiro Hiono, Aya Matsuu, Yuko Uchida, Ritsuko Iwata, Keita Matsuno, Masakazu Kuwahara, Toshiyo Yabuta, Tatsufumi Usui, Hiroshi Ito, Manabu Onuma, Yoshihiro Sakoda, Takehiko Saito, Koichi Otsuki, Toshihiro Ito, Hiroshi Kida
    EMERGING INFECTIOUS DISEASES 23 (4) 691 - 695 1080-6040 2017/04 [Refereed][Not invited]
     
    Highly pathogenic avian influenza viruses (HPAIVs) A(H5N6) were concurrently introduced into several distant regions of Japan in November 2016. These viruses were classified into the genetic clade 2.3.4.4c and were genetically closely related to H5N6 HPAIVs recently isolated in South Korea and China. In addition, these HPAIVs showed further antigenic drift.
  • Keita Matsuno, Yasuko Orba, Kimberly Maede-White, Dana Scott, Friederike Feldmann, Mifang Liang, Hideki Ebihara
    FRONTIERS IN MICROBIOLOGY 8 104  1664-302X 2017/01 [Refereed][Not invited]
     
    The pathogenesis of clinical manifestations caused by newly emerging tick-borne phleboviruses [i.e., Severe fever with thrombocytopenia syndrome virus (SFTSV) and Heartland virus (HRTV)], such as severe thrombocytopenia and lymphocytopenia, are not yet fully understood. In the present study, to establish an animal model mimicking the profile of fatal human cases, we examined the susceptibilities of adult mice from 12 strains, aged mice from two strains, and cynomolgus macaques to SFTSV and/or HRTV infections. However, none of these immunocompetent animals developed lethal diseases after infection with SFTSV or HRTV. Thus, we tested a lethal animal model of SFTSV infection using interferon-alpha/beta receptor knock-out (IFNAR(-/-)) mice to identify the target cell(s) of virus infection, as well as lesions that are potentially associated with hematological changes. IbaI-positive macrophages and Pax5-positive immature B cells overlapped with SFTSV-positive cells in the spleen and lymph nodes of IFNAR(-/-) mice, and IbaI- SFTSV-double positive cells were also observed in the liver and kidney, thereby suggesting crucial roles for macrophages in the pathogenesis of SFTSV infection in mice. In the mandibular lymph nodes and spleens of infected mice, we observed extensive necrosis comprising B220-positive B cells, which may be associated with severe lymphocytopenia. The results of this study suggest a resemblance between the IFNAR(-/-) mouse model and lethal infections in humans, as well as roles for multiple cells during pathogenesis in mice.
  • Ryo Nakao, Keita Matsuno, Yongjin Qiu, Junki Marilyama, Nao Eguchi, Naganori Nao, Masahiro Kajihara, Kentaro Yoshii, Hirofumi Sawa, Ayato Takada, Chihiro Sugimoto
    TICKS AND TICK-BORNE DISEASES 8 (1) 103 - 111 1877-959X 2017 [Refereed][Not invited]
     
    Ticks harbour various microorganisms, some of which act as pathogens of humans and animals. The recent advancement of genome sequencing technologies revealed that a wide range of previously unrecognised microorganisms exist in ticks. Continuous cell lines established from ticks could play a key role in the isolation of such microorganisms; however, tick cells themselves have been known to harbour symbiotic microorganisms. The present study aimed to characterise putative RNA viral sequences detected in the culture supernatant of one of the most frequently used tick cell lines, ISE6, which was derived from embryos of the blacklegged tick Ixodes scapularis. Viral particles purified from the culture supernatant were used for RNA extraction, followed by Illumina sequencing. The reads were de novo assembled and the resulting contigs were annotated by tBLASTx search. The results suggested that there were at least five putative viral sequences of four phylogenetically distinct lineages in ISE6 cells. The predominant viral sequence found in ISE6 cells, designated L scapularis iflavirus, was a member of the family Iflaviridae, which is an arthropod-infecting virus group. We also identified L and M segments of the family Bunyaviridae, which could not be classified into any of the five known genera, and a potential capsid protein related to Drosophila A virus. In addition to these previously unrecognised viruses, ISE6 was revealed to harbour a putative genome sequence of L scapularis-associated virus-1, which was reported in a recent metagenomic study of L scapularis itself. All the five putative viral sequences were detected by RT-PCR in both ISE6 cells and the culture supernatant. Electron microscopic analysis showed the existence of spherical virions with a varying diameter of 50-70 nm in the culture supernatant of ISE6 cells. Further studies are required to investigate the potential roles of ISE6-associated viruses in ticks. (C) 2016 Elsevier GmbH. All rights reserved.
  • Duc-Huy Chu, Masatoshi Okamatsu, Keita Matsuno, Takahiro Hiono, Kohei Ogasawara, Lam Thanh Nguyen, Long Van Nguyen, Tien Ngoc Nguyen, Thuy Thu Nguyen, Dong Van Pham, Dang Hoang Nguyen, Tho Dang Nguyen, Thanh Long To, Hung Van Nguyen, Hiroshi Kida, Yoshihiro Sakoda
    VETERINARY MICROBIOLOGY 192 194 - 203 0378-1135 2016/08 [Refereed][Not invited]
     
    A total of 3,045 environmental samples and oropharyngeal and cloacal swabs from apparently healthy poultry have been collected at three live bird markets (LBMs) at which practices were applied to reduce avian influenza (AI) virus transmission (intervention LBMs) and six conventional LBMs (non-intervention LBMs) in Thua Thien Hue province in 2014 to evaluate the efficacy of the intervention LBMs. The 178 AI viruses, including H3 (19 viruses), H4 (2), H5 (8), H6 (30), H9 (114), and H11 (5), were isolated from domestic ducks, muscovy ducks, chickens, and the environment. The prevalence of AI viruses in intervention LBMs (6.1%; 95% CI: 5.0-7.5) was similar to that in non-intervention LBMs (5.6%; 95% CI: 4.5-6.8; x(2) = 0.532; df = 1; P = 0.53) in the study area. Eight H5N6 highly pathogenic avian influenza (HPAI) viruses were isolated from apparently healthy ducks, muscovy ducks, and an environmental sample in an intervention LBM. The hemagglutinin genes of the H5N6 HPAI viruses belonged to the genetic Glade 23.4.4, and the antigenicity of the H5N6 HPAI viruses differed from the H5N1 HPAI viruses previously circulating in Vietnam. Phylogenetic and antigenic analyses of the H6 and H9 viruses isolated in both types of LBMs revealed that they were closely related to the viruses isolated from domestic birds in China, Group II of H6 viruses and Y280 lineage of H9 viruses. These results indicate that the interventions currently applied in LBMs are insufficient to control AI. A risk analysis should be conducted to identify the key factors contributing to Al virus prevalence in intervention LBMs. (C) 2016 Elsevier B.V. All rights reserved.
  • Masatoshi Okamatsu, Yurie Motohashi, Takahiro Hiono, Tomokazu Tamura, Kazuki Nagaya, Keita Matsuno, Yoshihiro Sakoda, Hiroshi Kida
    ARCHIVES OF VIROLOGY 161 (8) 2235 - 2242 0304-8608 2016/08 [Refereed][Not invited]
     
    Influenza viruses isolated from wild ducks do not replicate in chickens. This fact is not explained solely by the receptor specificity of the hemagglutinin (HA) from such viruses for target host cells. To investigate this restriction in host range, the fusion activities of HA molecules from duck and chicken influenza viruses were examined. Influenza viruses A/duck/Mongolia/54/2001 (H5N2) (Dk/MNG) and A/chicken/Ibaraki/1/2005 (H5N2) (Ck/IBR), which replicate only in their primary hosts, were used. The optimal pH for membrane fusion of Ck/IBR was 5.9, higher than that of Dk/MNG at 4.9. To assess the relationship between the optimal pH for fusion and the host range of avian influenza viruses, the optimal pH for fusion of 55 influenza virus strains isolated from ducks and chickens was examined. No correlation was found between the host range and optimal pH for membrane fusion by the viruses, and this finding applied also to the H5N1 highly pathogenic avian influenza viruses. The optimal pH for membrane fusion for avian influenza viruses was shown to not necessarily be correlated with their host range or pathogenicity in ducks and chickens.
  • Daisuke Fukui, Makiko Nakamura, Tsuyoshi Yamaguchi, Makiko Takenaka, Mami Murakami, Tokuma Yanai, Hideto Fukushi, Kazumi Yanagida, Gen Bando, Keita Matsuno, Masashi Nagano, Toshio Tsubota
    JOURNAL OF WILDLIFE DISEASES 52 (2) 230 - 241 0090-3558 2016/04 [Refereed][Not invited]
     
    In 2006-10, an epizootic of emerging avian pox occurred in Carrion Crows (Corvus corone) and Large-billed Crows (Corvus macrorhynchos), leading to mortality of juvenile crows in Hokkaido, the northernmost island of Japan. We diagnosed 27 crows with proliferative skin lesions (19 carcasses and eight biopsied cases [one in zoo captivity]) as avian pox clinically, histopathologically by detection of Avipoxvirus-specific 4b core protein (P4b) gene, and epidemiologically. The fatal cases demonstrated intensively severe infection and aggressive lesions with secondary bacterial infection. Since the first identification of avian pox in Sapporo, Japan, in 2006, the frequency of mortality events has increased, peaking in 2007-08. Mortalities have subsequently occurred in other areas, suggesting disease expansion. In Sapporo, prevalence of avian pox evaluated by field censuses during 2007-12 was 17.6% (6.6-27.2%), peaked during 2007-08 and 2008-09, and then decreased. All diseased crows were juveniles, except for one adult. The number of crows assembling in the winter roosts had been stable for >10 yr; however, it declined in 2007-08, decreased by about 50% in 2008-09, and recovered to the previous level in 2009-10, correlated with the avian pox outbreak. Thus, avian pox probably contributed to the unusual crow population decline. All P4b sequences detected in six specimens in Sapporo were identical and different from any previously reported sequences. The sequence detected in the zoo-kept crow was distinct from any reported clades, and interspecies transmission was suspected. This report demonstrates an emerging novel avian pox in the Japanese avifauna and in global populations of Carrion Crows and Large-billed Crows. Longitudinal monitoring is needed to evaluate its impact on the crow population.
  • Takahiro Hiono, Keita Matsuno, Kotaro Tuchiya, Zhifeng Lin, Masatoshi Okamatsu, Yoshihiro Sakoda
    Genome Announcements 4 (5) 2169-8287 2016 [Refereed][Not invited]
     
    Here, we report the complete genome sequence of the avian paramyxovirus serotype 5 strain APMV-5/budgerigar/Japan/TI/75, which was determined using the Illumina MiSeq platform. The determined sequence shares 97% homology and similar genetic features with the previously known genome sequence of avian paramyxovirus serotype 5 strain APMV-5/budgerigar/Japan/Kunitachi/74.
  • Takahiro Hiono, Masatoshi Okamatsu, Naoki Yamamoto, Kohei Ogasawara, Mayumi Endo, Saya Kuribayashi, Shintaro Shichinohe, Yurie Motohashi, Duc-Huy Chu, Mizuho Suzuki, Takaya Ichikawa, Tatsuya Nishi, Yuri Abe, Keita Matsuno, Kazuyuki Tanaka, Tsutomu Tanigawa, Hiroshi Kida, Yoshihiro Sakoda
    VETERINARY MICROBIOLOGY 182 108 - 115 0378-1135 2016/01 [Refereed][Not invited]
     
    Highly pathogenic avian influenza viruses (HPAIVs) have spread in both poultry and wild birds. Determining transmission routes of these viruses during an outbreak is essential for the control of avian influenza. It has been widely postulated that migratory ducks play crucial roles in the widespread dissemination of HPAIVs in poultry by carrying viruses along with their migrations; however close contacts between wild migratory ducks and poultry are less likely in modern industrial poultry farming settings. Therefore, we conducted experimental infections of HPAIVs and low pathogenic avian influenza viruses (LPAIVs) to chickens, domestic ducks, tree sparrows, jungle crows, and black rats to evaluate their roles in virus transmission. The results showed that chickens, ducks, sparrows, and crows were highly susceptible to HPAIV infection. Significant titers of virus were recovered from the sparrows and crows infected with HPAIVs, which suggests that they potentially play roles of transmission of HPAIVs to poultry. In contrast, the growth of LPAIVs was limited in each of the animals tested compared with that of HPAIVs. The present results indicate that these common synanthropes play some roles in influenza virus transmission from wild birds to poultry. (C) 2015 Elsevier B.V. All rights reserved.
  • Intracellular membrane association of classical swine fever virus NS4B is critical for viral RNA replication
    Tomokazu Tamura, Nicolas Ruggli, Masatoshi Okamatsu, Keita Matsuno, Yoshihiro Sakoda
    2015/11 [Refereed][Not invited]
  • 豚コレラウイルスの病原性発現の分子基盤
    田村友和, Nicolas Ruggli, 岡松正敏, 松野啓太, 迫田義博
    2015/11 [Refereed][Not invited]
  • Hirohito Ogawa, Hiroko Miyamoto, Eri Nakayama, Reiko Yoshida, Ichiro Nakamura, Hirofumi Sawa, Akihiro Ishii, Yuka Thomas, Emiko Nakagawa, Keita Matsuno, Masahiro Kajihara, Junki Maruyama, Naganori Nao, Mieko Muramatsu, Makoto Kuroda, Edgar Simulundu, Katendi Changula, Bernard Hang'ombe, Boniface Namangala, Andrew Nambota, Jackson Katampi, Manabu Igarashi, Kimihito Ito, Heinz Feldmann, Chihiro Sugimoto, Ladslav Moonga, Aaron Mweene, Ayato Takada
    JOURNAL OF INFECTIOUS DISEASES 212 S101 - S108 0022-1899 2015/10 [Refereed][Not invited]
     
    Fruit bats are suspected to be a natural reservoir of filoviruses, including Ebola and Marburg viruses. Using an enzyme-linked immunosorbent assay based on the viral glycoprotein antigens, we detected filovirus-specific immunoglobulin G antibodies in 71 of 748 serum samples collected from migratory fruit bats (Eidolon helvum) in Zambia during 2006-2013. Although antibodies to African filoviruses (eg, Zaire ebolavirus) were most prevalent, some serum samples showed distinct specificity for Reston ebolavirus, which that has thus far been found only in Asia. Interestingly, the transition of filovirus species causing outbreaks in Central and West Africa during 2005-2014 seemed to be synchronized with the change of the serologically dominant virus species in these bats. These data suggest the introduction of multiple species of filoviruses in the migratory bat population and point to the need for continued surveillance of filovirus infection of wild animals in sub-Saharan Africa, including hitherto nonendemic countries.
  • 豚コレラウイルス非構造蛋白NS4Bの機能と病原性に及ぼす影響
    田村友和, Nicolas Ruggli, 長島尚史, 岡松正敏, Artur Summerfield, 松野啓太, 喜田宏, 迫田義博
    2015/07 [Refereed][Not invited]
  • Makoto Kuroda, Daisuke Fujikura, Asuka Nanbo, Andrea Marzi, Osamu Noyori, Masahiro Kajihara, Junki Maruyama, Keita Matsuno, Hiroko Miyamoto, Reiko Yoshida, Heinz Feldmann, Ayato Takada
    JOURNAL OF VIROLOGY 89 (12) 6481 - 6493 0022-538X 2015/06 [Refereed][Not invited]
     
    Multiple host molecules are known to be involved in the cellular entry of filoviruses, including Ebola virus (EBOV); T-cell immunoglobulin and mucin domain 1 (TIM-1) and Niemann-Pick C1 (NPC1) have been identified as attachment and fusion receptors, respectively. However, the molecular mechanisms underlying the entry process have not been fully understood. We found that TIM-1 and NPC1 colocalized and interacted in the intracellular vesicles where EBOV glycoprotein (GP)-mediated membrane fusion occurred. Interestingly, a TIM-1-specific monoclonal antibody (MAb), M224/1, prevented GP-mediated membrane fusion and also interfered with the binding of TIM-1 to NPC1, suggesting that the interaction between TIM-1 and NPC1 is important for filovirus membrane fusion. Moreover, MAb M224/1 efficiently inhibited the cellular entry of viruses from all known filovirus species. These data suggest a novel mechanism underlying filovirus membrane fusion and provide a potential cellular target for antiviral compounds that can be universally used against filovirus infections.
  • Keita Matsuno, Carla Weisend, Masahiro Kajihara, Colette Matysiak, Brandi N. Williamson, Martin Simuunza, Aaron S. Mweene, Ayato Takada, Robert B. Tesh, Hideki Ebihara
    JOURNAL OF VIROLOGY 89 (1) 594 - 604 0022-538X 2015/01 [Refereed][Not invited]
     
    Until the recent emergence of two human-pathogenic tick-borne phleboviruses (TBPVs) (severe fever with thrombocytopenia syndrome virus [SFTSV] and Heartland virus), TBPVs have been neglected as causative agents of human disease. In particular, no studies have addressed the global distribution of TBPVs, and consequently, our understanding of the mechanism(s) underlying their evolution and emergence remains poor. In order to provide a useful tool for the ecological and epidemiological study of TBPVs, we have established a simple system that can detect all known TBPVs, based on conventional reverse transcription-PCR (RT-PCR) with degenerate primer sets targeting conserved regions of the viral L genome segment. Using this system, we have determined that several viruses that had been isolated from ticks decades ago but had not been taxonomically identified are novel TBPVs. Full-genome sequencing of these viruses revealed a novel fourth TBPV cluster distinct from the three known TBPV clusters (i.e., the SETS, Bhanja, and Uukuniemi groups) and from the mosquito/sandfly-borne phleboviruses. Furthermore, by using tick samples collected in Zambia, we confirmed that our system had enough sensitivity to detect a new TBPV in a single tick homogenate. This virus, tentatively designated Shibuyunji virus after the region of tick collection, grouped into a novel fourth TBPV cluster. These results indicate that our system can be used as a first-line screening approach for TBPVs and that this kind of work will undoubtedly lead to the discovery of additional novel tick viruses and will expand our knowledge of the evolution and epidemiology of TBPVs. IMPORTANCE Tick-borne phleboviruses (TBPVs) have been largely neglected until the recent emergence of two virulent viruses, severe fever with thrombocytopenia syndrome virus and Heartland virus. Little is known about the global distribution of TBPVs or how these viruses evolved and emerged. A major hurdle to study the distribution of TBPVs is the lack of tools to detect these genetically divergent phleboviruses. In order to address this issue, we have developed a simple, rapid, and cheap RT-PCR system that can detect all known TBPVs and which led to the identification of several novel phleboviruses from previously uncharacterized tick-associated virus isolates. Our system can detect virus in a single tick sample and novel TBPVs that are genetically distinct from any of the known TBPVs. These results indicate that our system will be a useful tool for the surveillance of TBPVs and will facilitate understanding of the ecology of TBPVs.
  • Osamu Noyori, Keita Matsuno, Masahiro Kajihara, Eri Nakayama, Manabu Igarashi, Makoto Kuroda, Norikazu Isoda, Reiko Yoshida, Ayato Takada
    VIROLOGY 446 (1-2) 152 - 161 0042-6822 2013/11 [Refereed][Not invited]
     
    The viral envelope glycoprotein (GP) is thought to play important roles in the pathogenesis of filovirus infection. It is known that GP expressed on the cell surface forms a steric shield over host proteins such as major histocompatibility complex class I and integrin pi, which may result in the disorder of cell-to-cell contacts and/or inhibition of the immune response. However, it is not clarified whether this phenomenon contributes to the pathogenicity of filoviruses. In this study, we found that the steric shielding efficiency differed among filovirus strains and was correlated with the difference in their relative pathogenicities. While the highly glycosylated mucin-like region of GP was indispensable, the differential shielding efficiency did not necessarily depend on the primary structure of the mucin-like region, suggesting the importance of the overall properties (e.g., flexibility and stability) of the GP molecule for efficient shielding of host proteins. (C) 2013 Elsevier Inc. All rights reserved.
  • Matsuno K, Weisend C, Travassos da Rosa AP, Anzick SL, Dahlstrom E, Porcella SF, Dorward DW, Yu XJ, Tesh RB, Ebihara H
    Journal of virology 87 (7) 3719 - 3728 0022-538X 2013/04 [Refereed][Not invited]
  • エボラウイルス表層糖タンパク質に対する糖鎖修飾制御メカニズムの解明
    藤平 陽彦, 宇佐美 克明, 伝田 香里, 松野 啓太, 篠原 康郎, 佐藤 あやの, 高田 礼人, 入村 達郎
    日本生化学会大会プログラム・講演要旨集 (公社)日本生化学会 85回 3T15 - 08 2012/12
  • Masahiro Kajihara, Andrea Marzi, Eri Nakayama, Takeshi Noda, Makoto Kuroda, Rashid Manzoor, Keita Matsuno, Heinz Feldmann, Reiko Yoshida, Yoshihiro Kawaoka, Ayato Takada
    JOURNAL OF VIROLOGY 86 (24) 13467 - 13474 0022-538X 2012/12 [Refereed][Not invited]
     
    The envelope glycoprotein (GP) of Marburg virus (MARV) and Ebola virus (EBOV) is responsible for virus entry into host cells and is known as the only target of neutralizing antibodies. While knowledge about EBOV-neutralizing antibodies and the mechanism for the neutralization of infectivity is being accumulated gradually, little is known about antibodies that can efficiently regulate MARV infectivity. Here we show that MARV GP-specific monoclonal antibodies AGP127-8 (IgG1) and MGP72-17 (IgM), which do not inhibit the GP-mediated entry of MARV into host cells, drastically reduced the budding and release of progeny viruses from infected cells. These antibodies similarly inhibited the formation of virus-like particles (VLPs) consisting of GP, the viral matrix protein, and nucleoprotein, whereas the Fab fragment of AGP127-8 showed no inhibitory effect. Morphological analyses revealed that filamentous VLPs were bunched on the surface of VLP-producing cells cultured in the presence of the antibodies. These results demonstrate a novel mechanism of the antibody-mediated inhibition of MARV budding, in which antibodies arrest unformed virus particles on the cell surface. Our data lead to the idea that such antibodies, like classical neutralizing antibodies, contribute to protective immunity against MARV and that the "classical" neutralizing activity is not the only indicator of a protective antibody that may be available for prophylactic and therapeutic use.
  • Allison Groseth, Keita Matsuno, Eric Dahlstrom, Sarah L. Anzick, Stephen F. Porcella, Hideki Ebihara
    JOURNAL OF VIROLOGY 86 (24) 13844 - 13845 0022-538X 2012/12 [Refereed][Not invited]
     
    Batai virus (BATV) is a widely distributed but poorly studied member of the Orthobunyavirus genus in the family Bunyaviridae and is of particular interest as a known participant in natural reassortment events. Both research and surveillance efforts on this and other related viruses have been hampered by the lack of available full-length sequence data covering all three genomic segments. Here, we report the complete genome sequence of four BATV strains (MM2222, Chittoor/IG-20217, UgMP-6830, and MS50) isolated from various geographical locations. Based on these data, we have determined that strain MS50 is in fact unrelated to BATV and likely represents as a novel genotype in the genus Orthobunyavirus.
  • Eri Nakayama, Daisuke Tomabechi, Keita Matsuno, Noriko Kishida, Reiko Yoshida, Heinz Feldmann, Ayato Takada
    JOURNAL OF INFECTIOUS DISEASES 204 S978 - S985 0022-1899 2011/11 [Refereed][Not invited]
     
    Methods. To investigate this antibody-dependent enhancement (ADE) in MARV infection, we produced mouse antisera and monoclonal antibodies (mAbs) to the GPs of MARV strains Angola and Musoke. Results. The infectivity of vesicular stomatitis virus pseudotyped with Angola GP in K562 cells was significantly enhanced in the presence of Angola GP antisera, whereas only minimal ADE activity was seen with Musoke GP antisera. This difference correlated with the percentage of hybridoma clones producing infectivity-enhancing mAbs. Using mAbs to MARV GP, we identified 3 distinct ADE epitopes in the mucinlike region on Angola GP. Interestingly, some of these antibodies bound to both Angola and Musoke GPs but showed significantly higher ADE activity for strain Angola. ADE activity depended on epitopes in the mucinlike region and glycine at amino acid position 547, present in the Angola but absent in the Musoke GP. Conclusions. These results suggest a possible link between ADE and MARV pathogenicity and provide new insights into the mechanisms underlying ADE entry of filoviruses.
  • Masahiro Kajihara, Keita Matsuno, Edgar Simulundu, Mieko Muramatsu, Osamu Noyori, Rashid Manzoor, Eri Nakayama, Manabu Igarashi, Daisuke Tomabechi, Reiko Yoshida, Masatoshi Okamatsu, Yoshihiro Sakoda, Kimihito Ito, Hiroshi Kida, Ayato Takada
    JAPANESE JOURNAL OF VETERINARY RESEARCH 59 (2-3) 89 - 100 0047-1917 2011/08 [Refereed][Not invited]
     
    In 2010, an H5N1 highly pathogenic avian influenza virus (HPAIV) was isolated from feces of apparently healthy ducks migrating southward in Hokkaido, the northernmost prefecture of Japan. The H5N1 HPAIVs were subsequently detected in domestic and wild birds at multiple sites corresponding to the flyway of the waterfowl having stopovers in the Japanese archipelago. The Hokkaido isolate was genetically nearly identical to H5N1 HPAIVs isolated from swans in the spring of 2009 and 2010 in Mongolia, but less pathogenic in experimentally infected ducks than the 2009 Mongolian isolate. These findings suggest that H5N1 HPAIVs with relatively mild pathogenicity might be selected and harbored in the waterfowl population during the 2009-2010 migration seasons. Our data provide "early warning" signals for preparedness against the unprecedented situation in which the waterfowl reservoirs serve as perpetual sources and disseminators of HPAIVs.
  • Katsuaki Usami, Keita Matsuno, Manabu Igarashi, Kaori Denda-Nagai, Ayato Takada, Tatsuro Irimura
    BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 407 (1) 74 - 78 0006-291X 2011/04 [Refereed][Not invited]
     
    Ebola virus (EBOV) infection is initiated by the interaction of the viral surface envelope glycoprotein (GP) with the binding sites on target cells. Differences in the mortality among different species of the Ebola viruses, i.e., Zaire ebolavirus (ZEBOV) and Reston ebolavirus (REBOV), correspond to the in vitro infectivity of the pseudo-typed virus constructed with the GPs in cells expressing macrophage galactose-type calcium-type lectin (MGL/CD301). Through mutagenesis of GP2, the transmembrane-anchored subunit of GP, we found that residues 502-527 of the GP2 sequence determined the different infectivity between VSV-ZEBOV GP and -REBOV GP in MGL/CD301-expressing cells and a histidine residue at position 516 of ZEBOV GP2 appeared essential in the differential infectivity. These findings may provide a clue to clarify a molecular basis of different pathogenicity among EBOV species. (C) 2011 Elsevier Inc. All rights reserved.
  • Keita Matsuno, Eri Nakayama, Osamu Noyori, Andrea Marzi, Hideki Ebihara, Tatsuro Irimura, Heinz Feldmann, Ayato Takada
    BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 403 (1) 144 - 148 0006-291X 2010/12 [Refereed][Not invited]
     
    Cellular C-type lectins have been reported to facilitate filovirus infection by binding to glycans on filovirus glycoprotein (GP). However, it is not clearly known whether interaction between C-type lectins and GP mediates all the steps of virus entry (i.e., attachment, internalization, and membrane fusion). In this study, we generated vesicular stomatitis viruses pseudotyped with mutant GPs that have impaired structures of the putative receptor binding regions and thus reduced ability to infect the monkey kidney cells that are routinely used for virus propagation. We found that infectivities of viruses with the mutant GPs dropped in C-type lectin-expressing cells, parallel with those in the monkey kidney cells, whereas binding activities of these GPs to the C-type lectins were not correlated with the reduced infectivities. These results suggest that C-type lectin-mediated entry of filoviruses requires other cellular molecule(s) that may be involved in virion internalization or membrane fusion. (C) 2010 Elsevier Inc. All rights reserved.
  • Eri Nakayama, Ayaka Yokoyama, Hiroko Miyamoto, Manabu Igarashi, Noriko Kishida, Keita Matsuno, Andrea Marzi, Heinz Feldmann, Kimihito Ito, Masayuki Saijo, Ayato Takada
    CLINICAL AND VACCINE IMMUNOLOGY 17 (11) 1723 - 1728 1556-6811 2010/11 [Refereed][Not invited]
     
    Several enzyme-linked immunosorbent assays (ELISAs) for the detection of filovirus-specific antibodies have been developed. However, diagnostic methods to distinguish antibodies specific to the respective species of filoviruses, which provide the basis for serological classification, are not readily available. We established an ELISA using His-tagged secreted forms of the transmembrane glycoproteins (GPs) of five different Ebola virus (EBOV) species and one Marburg virus (MARV) strain as antigens for the detection of filovirus species-specific antibodies. The GP-based ELISA was evaluated by testing antisera collected from mice immunized with virus-like particles as well as from humans and nonhuman primates infected with EBOV or MARV. In our ELISA, little cross-reactivity of IgG antibodies was observed in most of the mouse antisera. Although sera and plasma from some patients and monkeys showed notable cross-reactivity with the GPs from multiple filovirus species, the highest reactions of IgG were uniformly detected against the GP antigen homologous to the virus species that infected individuals. We further confirmed that MARV-specific IgM antibodies were specifically detected in specimens collected from patients during the acute phase of infection. These results demonstrate the usefulness of our ELISA for diagnostics as well as ecological and serosurvey studies.
  • Yoshihiro Sakoda, Sengee Sugar, Damdinjav Batchluun, Tseren-Ochir Erdene-Ochir, Masatoshi Okamatsu, Norikazu Isoda, Kosuke Soda, Hiroki Takakuwa, Yoshimi Tsuda, Naoki Yamamoto, Noriko Kishida, Keita Matsuno, Eri Nakayama, Masahiro Kajihara, Ayaka Yokoyama, Ayato Takada, Ruuragchaa Sodnomdarjaa, Hiroshi Kida
    VIROLOGY 406 (1) 88 - 94 0042-6822 2010/10 [Refereed][Not invited]
     
    H5N1 highly pathogenic avian influenza (HPAI) viruses were isolated from dead wild waterfowl at Khunt, Erkhel, Doityn Tsagaan, Doroo, and Ganga Lakes in Mongolia in July 2005, May 2006, May 2009, July 2009, and May 2010, respectively. The isolates in 2005 and 2006 were classified into genetic clade 2.2, and those in 2009 and 2010 into clade 2.3.2. A/whooper swan/Mongolia/6/2009 (H5N1) experimentally infected ducks and replicated systemically with higher mortality than that of the isolates in 2005 and 2006. Intensive surveillance of avian influenza in migratory waterfowl flying from their nesting lakes in Siberia to Mongolia in every autumn indicate that HPAI viruses have not perpetuated at their nesting lakes until 2009. The present results demonstrate that wild waterfowl were sporadically infected with H5N1 HPAI viruses prevailing in domestic poultry in the southern Asia and died in Mongolia on the way back to their northern territory in spring. (C) 2010 Elsevier Inc. All rights reserved.
  • Keita Matsuno, Noriko Kishida, Katsuaki Usami, Manabu Igarashi, Reiko Yoshida, Eri Nakayama, Masayuki Shimojima, Heinz Feldmann, Tatsuro Irimura, Yoshihiro Kawaoka, Ayato Takada
    JOURNAL OF VIROLOGY 84 (10) 5140 - 5147 0022-538X 2010/05 [Refereed][Not invited]
     
    The glycoproteins (GPs) of filoviruses are responsible for virus entry into cells. It is known that GP interacts with cellular C-type lectins for virus attachment to cells. Since primary target cells of filoviruses express C-type lectins, C-type lectin-mediated entry is thought to be a possible determinant of virus tropism and pathogenesis. We compared the efficiency of C-type lectin-mediated entry between Marburg virus strains Angola and Musoke by using a vesicular stomatitis virus (VSV) pseudotype system. VSV pseudotyped with Angola GP (VSV-Angola) infected K562 cells expressing the C-type lectin, human macrophage galactose-type C-type lectin (hMGL), or dendritic cell-specific ICAM-3-grabbing nonintegrin (DC-SIGN) more efficiently than VSV pseudotyped with Musoke GP (VSV-Musoke). Unexpectedly, the binding affinity of the C-type lectins to the carbohydrates on GPs did not correlate with the different efficiency of C-type lectin-mediated entry. Site-directed mutagenesis identified the amino acid at position 547, which switched the efficiency of C-type lectin-mediated entry. In a three-dimensional model of GP, this amino acid was in close proximity to the putative site of cathepsin processing. Interestingly, the cathepsin inhibitors reduced the infectivity of VSV-Angola less efficiently than that of VSV-Musoke in C-type lectin-expressing K562 cells, whereas only a limited difference was found in control cells. The amino acid at position 547 was critical for the different effects of the inhibitors on the virus infectivities. These results suggest that the efficiency of C-type lectin-mediated entry of filoviruses is controlled not only by binding affinity between C-type lectins and GP but also by mechanisms underlying endosomal entry, such as proteolytic processing by the cathepsins.
  • MGL/CD301を介するエボラウイルス感染増強に関わる表層糖蛋白質の構造的特徴(Structural features of Ebola viral envelope glycoproteins responsible for the enhancement of infection through the interaction with MGL/CD301)
    宇佐美 克明, 松野 啓太, 五十嵐 学, 伝田 香里, 高田 礼人, 入村 達郎
    日本生化学会大会プログラム・講演要旨集 82回 4T20p - 16 2009/09
  • Nicolas Ruggli, Artur Summerfield, Ana R. Fiebach, Laurence Guzylack-Piriou, Oliver Bauhofer, Catherine G. Lamm, Sandro Waltersperger, Keita Matsuno, Luzia Liu, Markus Gerber, Kyung H. Choi, Martin A. Hofmann, Yoshihiro Sakoda, Jon-Duri Tratschin
    JOURNAL OF VIROLOGY 83 (2) 817 - 829 0022-538X 2009/01 [Refereed][Not invited]
     
    Pestiviruses prevent alpha/beta interferon (IFN-alpha/beta) production by promoting proteasomal degradation of interferon regulatory factor 3 (IRF3) by means of the viral N-pro nonstructural protein. N-pro is also an autoprotease, and its amino-terminal coding sequence is involved in translation initiation. We previously showed with classical swine fever virus (CSFV) that deletion of the entire N-pro gene resulted in attenuation in pigs. In order to elaborate on the role of the N-pro-mediated IRF3 degradation in classical swine fever pathogenesis, we searched for minimal amino acid substitutions in N-pro that would specifically abrogate this function. Our mutational analyses showed that degradation of IRF3 and autoprotease activity are two independent but structurally overlapping functions of N-pro. We describe two mutations in N-pro that eliminate N-pro-mediated IRF3 degradation without affecting the autoprotease activity. We also show that the conserved standard sequence at these particular positions is essential for N-pro to interact with IRF3. Surprisingly, when these two mutations are introduced independently in the backbones of highly and moderately virulent CSFV, the resulting viruses are not attenuated, or are only partially attenuated, in 8- to 10-week-old pigs. This contrasts with the fact that these mutant viruses have lost the capacity to degrade IRF3 and to prevent IFN-alpha/beta induction in porcine cell lines and monocyte-derived dendritic cells. Taken together, these results demonstrate that contrary to previous assumptions and to the case for other viral systems, impairment of IRF3-dependent IFN-alpha/beta induction is not a prerequisite for CSFV virulence.
  • Ken-ichiro Kameyama, Yoshihiro Sakoda, Keita Matsuno, Asako Ito, Motoshi Tajima, Shigeyuki Nakamura, Hiroshi Kida
    MICROBIOLOGY AND IMMUNOLOGY 52 (5) 277 - 282 0385-5600 2008/05 [Refereed][Not invited]
     
    The NS2-3 of BVDV is cleaved in cultured cells infected with cp BVDV but not in those infected with ncp BVDV when tested more than 10 hours post infection. However, it is not known whether cleavage of NS2-3 occurs in vivo. In the present study, cleavage of NS2-3 in cattle persistently infected with BVDV was investigated. All BVDV isolated from PI animals were of the ncp biotype, and NS2-3 proteins were detected in bovine fetal muscular cells infected with these viruses. On the other hand, in the leukocytes of those PI animals, NS3 proteins, products of the cleavage of NS2-3 proteins, were detected. In addition, the NS3 proteins were also detected in leukocytes artificially infected with ncp BVDV. These results reveal that the NS2-3 protein of BVDV is cleaved in leukocytes. Furthermore, NS3 proteins were detected in many tissues of PI cattle, such as lymphoid tissue, brain, thyroid, lung, and kidney. These results suggest that the NS2-3 protein of ncp BVDV cleaves in vivo.
  • Keita Matsuno, Yoshihiro Sakoda, Ken-ichiro Kameyama, Kyuzo Tamai, Asako Ito, Hiroshi Kida
    JOURNAL OF VETERINARY MEDICAL SCIENCE 69 (5) 515 - 520 0916-7250 2007/05 [Refereed][Not invited]
     
    The 475 strains of bovine viral diarrhea virus (BVDV) isolated from cattle in 12 prefectures of Japan in the last 7 years were phylo.genetically classified as BVDV-1 or BVDV-2 on the basis of the nucleotide sequence of the 5'-untransiated region. BVDV-1 strains were further subtyped as 1a (101 strains), 1b (163), 1c (128), 1j (3), and So CP/75-like (1), and all of the 79 BVDV-2 strains belonged to subtype 2a. These 2a BVDVs contain two isolates that had high nucleotide identities with those of highly pathogenic BVDV-2 strains reported in North America (Pellerin et al., 1994). However, acute infection with severe mortality like North American outbreak was not observed and most of the present BVDV-2 strains were isolated from persistently infected (PI) cattle showing mild or no clinical sign. Moreover, it was revealed that 61.5% of the 39 PI cattle with cytopathogenic BVDVs did not show typical mucosal disease and 54.6% of the 405 PI animals only with non-cytopathogenic BVDVs were apparently healthy. The present results indicate that the prevention of the infection with an appropriate vaccine and active surveillance covering healthy cattle are required for the control of BVD.

Conference Activities & Talks

  • 中尾亮, 木下豪太, 齋藤歩, 邱永晋, 松野啓太, 杉本千尋, 片倉賢
    日本獣医学会学術集会講演要旨集  2017/08
  • 岡松正敏, 日尾野隆大, 菊谷祐斗, 鈴木瑞穂, NGUYEN Thanh‐Lam, 松野啓太, 松野啓太, 迫田義博, 迫田義博
    日本獣医学会学術集会講演要旨集  2017/08
  • Genetic and antigenic characterization of H13 avian influenza viruses(和訳中)  [Not invited]
    Wang Zu Jyun, 菊谷 祐斗, Nguyen Thanh-Lam, 松野 啓太, 岡松 正敏, 迫田 義博
    日本獣医学会学術集会講演要旨集  2017/08
  • Rapid and broad detection of H5 hemagglutinin by an immunochromatographic kit using novel monoclonal antibody against a 2.3.4.4 highly pathogenic avian influenza virus(和訳中)  [Not invited]
    Nguyen Thanh-Lam, 中石 和成, 本島 桂子, 大河原 彩子, 日尾野 隆大, 松野 啓太, 岡松 正敏, 高田 礼人, 喜田 宏, 迫田 義博
    日本獣医学会学術集会講演要旨集  2017/08
  • 2016-2017年冬季に北日本で野鳥及び飼育鳥から分離されたH5N6高病原性鳥インフルエンザウイルスの性状解析  [Not invited]
    岡松 正敏, 日尾野 隆大, 菊谷 祐斗, 鈴木 瑞穂, Nguyen Thanh-Lam, 松野 啓太, 迫田 義博
    日本獣医学会学術集会講演要旨集  2017/08
  • H13鳥インフルエンザウイルスの遺伝子と抗原の性状(Genetic and antigenic characterization of H13 avian influenza viruses)  [Not invited]
    Wang Zu Jyun, 菊谷 祐斗, Nguyen Thanh-Lam, 松野 啓太, 岡松 正敏, 迫田 義博
    日本獣医学会学術集会講演要旨集  2017/08
  • 2.3.4.4高病原性鳥インフルエンザウイルスに対する新規モノクローナル抗体を用いた免疫クロマトグラフィーキットによるH5ヘマグルチニンの迅速かつ広範囲検出(Rapid and broad detection of H5 hemagglutinin by an immunochromatographic kit using novel monoclonal antibody against a 2.3.4.4 highly pathogenic avian influenza virus)  [Not invited]
    Nguyen Thanh-Lam, 中石 和成, 本島 桂子, 大河原 彩子, 日尾野 隆大, 松野 啓太, 岡松 正敏, 高田 礼人, 喜田 宏, 迫田 義博
    日本獣医学会学術集会講演要旨集  2017/08
  • 齋藤歩, 中尾亮, THU May June, 邱永晋, 松野啓太, 松野啓太, 杉本千尋, 杉本千尋, 片倉賢
    日本獣医学会学術集会講演要旨集  2016/08
  • 柴田明弘, 日尾野隆大, 福原久江, 住吉理穂, 大河原彩子, 松野啓太, 松野啓太, 岡松正敏, 迫田義博, 迫田義博, 尾坂優之
    日本獣医学会学術集会講演要旨集  2016/08
  • 迫田義博, 迫田義博, BAZARRAGCHAA Enkhbold, MUNKHDUUREN Shatar, 若森史穂, 日尾野隆大, 松野啓太, 松野啓太, 岡松正敏, BATCHULUUN Damdinjav, 梅村孝司
    日本獣医学会学術集会講演要旨集  2016/08
  • ワクチン接種後の鶏におけるH5鳥インフルエンザウイルスの抗原多様性の選択(Selection of antigenic variants of H5 avian influenza viruses in vaccinated chickens)  [Not invited]
    Nguyen Thanh-Lam, 西 達也, 七戸 新太郎, Chu Duc-Huy, 日尾野 隆大, 松野 啓太, 岡松 正敏, 喜田 宏, 迫田 義博
    日本獣医学会学術集会講演要旨集  2016/08
  • 鳥居志保, 鳥居志保, 松野啓太, 松野啓太, 中尾亮, 邱永晋, 梶原将大, 直亨則, 村松美笑子, 海老原秀喜, 高田礼人, 高田礼人
    日本分子生物学会年会プログラム・要旨集(Web)  2016
  • 松野啓太, 松野啓太, 下田宙, 鳥居志保, 邱永晋, 中尾亮, 梶原将大, 岡松正敏, 迫田義博, 迫田義博, 奥村敦, 奥村敦, 高田礼人, 高田礼人, 前田健, 海老原秀喜
    日本獣医学会学術集会講演要旨集  2015/08
  • 日尾野隆大, 岡松正敏, 五十嵐学, 五十嵐学, MCBRIDE Ryan, DE VIRES Robert, PAULSON James, 松野啓太, 松野啓太, 迫田義博, 迫田義博, 喜田宏, 喜田宏, 喜田宏
    日本獣医学会学術集会講演要旨集  2015/08
  • 田村友和, RUGGLI Nicolas, 松野啓太, 松野啓太, 岡松正敏, 迫田義博, 迫田義博
    日本獣医学会学術集会講演要旨集  2015/08
  • 2014年のベトナムにおける介入有りまたは介入なしの生鳥市場にて単離された鳥インフルエンザウイルスの性状解析(Characterization of avian influenza viruses isolated in live bird markets with and without intervention in Vietnam in 2014)  [Not invited]
    Chu Duc-Huy, 岡松 正敏, 松野 啓太, 日尾野 隆大, 小笠原 浩平, 鈴木 瑞穂, Nguyen Thanh Lam, 喜田 宏, 迫田 義博
    日本獣医学会学術集会講演要旨集  2015/08
  • エボラウイルス表層糖タンパク質に対する糖鎖修飾制御メカニズムの解明  [Not invited]
    藤平 陽彦, 宇佐美 克明, 伝田 香里, 松野 啓太, 篠原 康郎, 佐藤 あやの, 高田 礼人, 入村 達郎
    日本生化学会大会プログラム・講演要旨集  2012/12
  • 野依修, 松野啓太, 梶原将大, 中山絵里, 五十嵐学, 磯田典和, 吉田玲子, 高田礼人
    日本ウイルス学会学術集会プログラム・抄録集  2012/10
  • 梶原将大, MARZI Andrea, 中山絵里, 野田岳志, 黒田誠, RASHID Manzoor, 松野啓太, FELDMANN Heinz, 吉田玲子, 河岡義裕, 高田礼人
    日本獣医学会学術集会講演要旨集  2012/08

MISC

Research Grants & Projects

  • 宿主RNAメチルトランスフェラーゼを標的とした抗インフルエンザウイルス薬の探索
    日本学術振興会：科学研究費助成事業 国際共同研究加速基金(国際共同研究強化(B))
    Date (from‐to) : 2022/10 -2026/03 
    Author : 五十嵐 学, 松野 啓太, 日尾野 隆大
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2022/04 -2025/03 
    Author : 松尾 栄子, 松野 啓太
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2020/04 -2023/03 
    Author : 五十嵐 学, 広川 貴次, 阿部 貴志, 松野 啓太
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2019/04 -2023/03 
    Author : 松野 啓太, 山口 宏樹, 大場 靖子, 梶原 将大
     
    本年度は主に、昨年度までに検出あるいは分離培養に成功したマダニ由来ウイルスについての性状解析を実施した。さらに、昨年度に報告したマダニ咬傷後に発熱を呈した患者から検出されたオルソナイロウイルス（Yezoウイルス)が分布していると考え られる北海道において、このウイルスを対象とした性状解析ならびに野外調査を実施した。なお、Yezoウイルスの調査については、他研究費との連携により効率的に展開した。また、マダニからオルソナイロウイルスを検出する系を樹立し、実際に北海道のマダニから複数のオルソナイロウイルスを検出した。本年度は新型コロナウ イルス感染拡大の影響で、海外でのマダニ採集が引き続き困難になったため、研究協力者からマダニを送付してもらうなどの代替策を進め、採集地域が限定されることを防いだ。さらに、実験室内で人為的にウイルスを接種したマダニを用いた実験モデルからのウイルス検出・分離培養方法検証を進め、状況が改善した際に野外調査を精力的に進められるよう準備を行った。 マダニから分離培養された各微生物については、遺伝情報解読と病原性解析の2つの性状比較解析を実施し、マダニから検出された各微生物は、サンガーシークエンサーと次世代シークエンサーを併用して遺伝子配列を解読した。さらに、これまでに収集あるいは分離培養したウイルスについて、実験動物を用いて病原性の検討を実施した。これらの結果を用いて、微生物のプロファイリングに用いることができる基礎的データを収集し、各微生物について塩基配列およびアミノ酸配列に基づいて病原性を推定する方法の検討を開始した。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2017/07 -2021/03 
    Author : Matsuno Keita
     
    Infectious diseases caused by arboviruses (viruses transmitted by blood-sucking arthropods and can also grow in the arthropods), such as dengue fever and SFTS, have become a severe problem on public health worldwide. A common feature of arboviruses is that they can grow in both vertebrates and arthropods. In this study, we compared host factor networks between vertebrates and arthropods, and extracted a homologous core network. We then identified several host factors that are likely to be associated with arbovirus replication in cells.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2016/06 -2021/03 
    Author : Sawa Hirofumi
     
    Blood-sucking arthropods, such as mosquitoes and ticks, have been studied as vectors of pathogens, including zoonotic viruses. In this study, we examined especially endogenous viruses in ticks and mosquitoes and investigated their roles in nature under the “dance floor” hypothesis; in blood-sucking arthropods, their indigenous microorganisms and those from human or animal blood are communicating each other. As a result, we have discovered new endogenous viruses in the mosquitoes and ticks collected worldwide and found that these viruses may have co-evolved with their hosts.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2016/04 -2019/03 
    Author : MATSUNO Keita, Kajihara Masahiro, Ebihara Hideki
     
    Sever fever with thrombocytopenia syndrome (SFTS) virus causes fatal febrile illness in humans and has obtained lots of attention in Eastern Asia, including Japan. In the present study, the present study aims to reveal the evolutional process in which SFTS virus increases its virulence to humans by comparing tick-borne phleboviruses closely related to SFTS virus. Novel tick-borne phleboviruses were identified in Japan and also in abroad, and wild animals were suggested to be infected with these viruses. Tick-borne phleboviruses seem to coevolve with ticks, and acquisition of NSs gene could be associated with SFTS virus virulence.
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2015/08 -2016/03 
    Author : 松野 啓太
     
    北海道を中心とした日本国内各地、ならびに海外各地において、マダニを採集しフレボウイルス遺伝子のスクリーニングを行った。合計4属10種約2千匹のマダニより、プールを含む94検体中でフレボウイルス遺伝子を検出した。検出されたフレボウイルス遺伝子の塩基配列を系統解析したところ、日本のマダニから検出されたフレボウイルス遺伝子は11群の、海外2カ国のマダニから検出されたウイルスはそれぞれ独立した群を形成し、SFTSウイルスとは遺伝的に大きく離れていた。日本の5群は既存のどのフレボウイルス種とも系統的に異なり、新規フレボウイルスである可能性が示唆された。本研究では、日本国内外のマダニからフレボウイルス遺伝子を検出し、マダニ中には、これまで知られている以上に多様なフレボウイルスが存在する可能性を明らかにした。フレボウイルス遺伝子が検出されたマダニ乳剤を培養細胞に接種し、ウイルス分離を試みたところ、日本の限定された地域で採集されたシュルツェマダニからのみ検出される互いに近縁な2種の新規フレボウイルスの分離に成功した。これらのウイルスの遺伝子全長配列を次世代シークエンサーにより決定したところ、マダニ由来フレボウイルスのいずれともまったく異なる新しい系統に属することが分かった。さらに、このウイルスをC57BL/6マウスに皮下接種したところ、感染3日後に脾臓でのウイルス増殖が確認され、哺乳動物での増殖性を有していることが明らかになった。
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2008 -2010 
    Author : 松野 啓太
     
    これまで、本研究によってマールブルグウイルス株間のC型レクチン介在性細胞侵入効率は表面糖タンパク質GP上の547番目のアミノ酸によって決まり、このアミノ酸はC型レクチン介在性細胞侵入の際に、GPのcathepsin感受性を決める因子である可能性が示された。このアミノ酸の違いによるウイルス感染効率の差は、C型レクチンを強制発現させた細胞でのみ観察され、マールブルグウイルスのC型レクチン介在性細胞侵入では、本来の細胞侵入機構と異なる仕組みによってウイルスの細胞侵入効率が制御されているかもしれない。 フィロウイルスは通常、GP上のレセプター結合領域と細胞表面の未同定の宿主因子との結合によって細胞に吸着し、細胞内に侵入すると考えられる。一方で、C型レクチンはGP上の糖鎖を認識するため、レセプター結合領域以外の領域とも結合できる。そこで、本研究では、レセプター結合領域に変異を加えてその機能を欠損させ、C型レクチン介在性の細胞侵入が起きるかどうかを検討した。レセプター結合領域に変異を加えたGPをまとったシュードタイプウイルスは、野生型GPを持つウイルスが効率良く感染するVero細胞などへの感染性が低下した。さらに、C型レクチン強制発現細胞においても、これらの変異GPを持つウイルスの感染性は同様に低下し、C型レクチンの存在により感染性が回復することはなかった。したがって、C型レクチンとGPとの結合はフィロウイルス感染を担うことはできず、その役割は限定的であると考えられる。

Educational Activities

Teaching Experience

  • Advanced Lecture on Transboundary Diseases
    開講年度 : 2021
    課程区分 : 博士後期課程
    開講学部 : 国際感染症学院

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