Kagoshima University · Joint Graduate School of Veterinary Medicine / Joint Faculty of Veterinary Medicine

Research keywordsveterinary virology・avian influenza・reverse genetics・virus surveillance・highly pathogenic avian influenza・animal infectious diseases

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• Inoue A., Goda I., Kojima I., Esaki M., Okuya K., Ozawa M. . Establishment of a circular polymerase extension reaction–based reverse genetics system for porcine reproductive and respiratory sy2026 · 記述言語： 日本語 掲載種別： 研究論文（学術雑誌） 出版者・発行元： Veterinary Microbiology Porcine reproductive and respiratory syndrome virus (PRRSV) continues to cause substantial economic losses in the global swine industry. Reverse genetics is an essential approach for elucidating viral replication mechanisms, pathogenicity, and vaccine design; however, existing reverse genetics systems for PRRSV are often technically demanding and time-consuming due to the large and genetically unstable viral genome. Here, we established a reverse genetics system for PRRSV based on the circular polymerase extension reaction (CPER), a bacteria-free method for assembling full-length viral genomes. Infectious PRRSV was successfully rescued following transfection of CPER-assembled DNA into human embryonic kidney-derived HEK293T cells. The rescued virus exhibited growth kinetics and plaque morphology comparable to those of the parental strain in porcine alveolar macrophage-derived PAM-T43 cells. To demonstrate the applicability of this system for genetic manipulation, targeted synonymous mutations were introduced into the ORF5 gene, and the resulting mutant virus was successfully recovered and genetically confirmed. These results indicate that the CPER-based reverse genetics system provides a rapid and flexible platform for generating genetically defined PRRSV variants. This approach is expected to facilitate studies on PRRSV pathogenesis, antigenic variation, and vaccine development, thereby contributing to improved control strategies for this economically important swine disease. DOI： 10.1016/j.vetmic.2026.111053 Scopus PubMed
• Okagawa Tomohiro, Nojiri Naomi, Yoshida-Furihata Hazuka, Nao Naganori, Tominaga Misono, Kohara Junko, Gondaira Satoshi, Higuchi Hidetoshi, Takeda Yohei, Ogawa Haruko, Yamada Shinji, Murakami Kenji, Suzuki Yasunori, Takai Shinji, Maezawa Masaki, Inokuma Hisashi, Shimizu Kaori, Inoshima Yasuo, Usui Tatsufumi, Tagawa Michihito, Yamamoto Mari, Mekata Hirohisa, Esaki Mana, Ozawa Makoto, Matsudaira Takahiro, Maekawa Naoya, Murata Shiro, Ohashi Kazuhiko, Saito Masumichi, Konnai Satoru2025 · 記述言語： 英語 出版者・発行元： (公社)日本獣医学会
• Esaki M., Okuya K., Onuma M., Ozawa M. . Genetically distinct H5N2 high pathogenicity avian influenza virus isolated from a peregrine falcon on Amami-Oshima Island, Japan, harboring enhanced p2025 · 記述言語： 日本語 掲載種別： 研究論文（学術雑誌） 出版者・発行元： Virology We report the first confirmed case of high pathogenicity avian influenza virus (HPAIV) infection in a peregrine falcon (Falco peregrinus) on Amami-Oshima Island, a region known for its unique biodiversity. The isolate, A/peregrine falcon/Kagoshima/5704A001/2025 (H5N2), showed genetic and phylogenetic divergence across all eight gene segments. Specific amino acids in the PA protein associated with increased pathogenicity in birds and mammals were also identified. Despite global surveillance, related ancestral viruses remain unreported. These findings highlight the need for expanded geographic surveillance and timely, transparent data sharing to better track and respond to emerging HPAIV threats. DOI： 10.1016/j.virol.2026.110794 Scopus PubMed
• Isoda N., Hew L.Y., Nishikawa K., Takaya F., Shimazu Y., Kobayashi D., Nabeshima K., Honjyo H., Esaki M., Okuya K., Soda K., Ito H., Kumagai A., Nishiura H., Hiono T., Takakuwa H., Usui T., Ozawa M.,2024 · 記述言語： 日本語 掲載種別： 研究論文（学術雑誌） 出版者・発行元： Pathogens Genetic and antigenic analyses were performed on highly pathogenic avian influenza viruses (HPAIVs) isolated in Hokkaido, northern Japan, during the winter of 2024–2025. Ninety-eight HPAIVs were isolated from feces of waterfowl, tracheal swabs from dead wild birds, or lung homogenates from dead chickens. Phylogenetic analysis of the hemagglutinin (HA) gene from 47 representative isolates revealed that all sequences belonged to the G2d subgroup of clade 2.3.4.4b H5HA, which has been the dominant lineage in Hokkaido since the winter of 2021–2022. These isolates were further divided into three major groups within the subgroup. The HPAIVs isolated in the Republic of Korea, China, and North America were genetically closely related to the Hokkaido isolates, whereas no HPAIVs genetically related to European strains or those detected in North American cattle were identified. Furthermore, HPAIVs isolated from seabirds were genetically closely related to those found in dead marine mammals along the eastern coast of Hokkaido in the spring of 2025. No apparent antigenic differences were observed between the HPAIVs isolated in this study and those from previous seasons. These findings highlight the wide distribution of HPAIVs in Hokkaido, particularly from Asian and North American lineages, and underscore the importance of continuous surveillance. DOI： 10.3390/pathogens14090951 Scopus PubMed

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