Genetic Diversity of Highly Pathogenic Avian Influenza Viruses Isolated in Hokkaido, Japan, During Winter 2024–2025
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.
Authors
- Kosuke Soda (ORCID: https://orcid.org/0000-0001-9116-9001)
- Yoshihiro Sakoda (ORCID: https://orcid.org/0000-0001-7021-1688)
- Kei Nabeshima (ORCID: https://orcid.org/0000-0003-1217-0544)
- Mana Esaki (ORCID: https://orcid.org/0009-0001-3440-2687)
- Hisako Honjyo
- Tatsufumi Usui (ORCID: https://orcid.org/0000-0003-1726-1293)
- Kosuke Okuya (ORCID: https://orcid.org/0000-0002-7987-9884)
- Yuko Uchida (ORCID: https://orcid.org/0000-0002-5833-5917)
- Fumihito Takaya
- Hayate Nishiura (ORCID: https://orcid.org/0000-0002-0882-4165)
- Kazuki Nishikawa
- Asuka Kumagai
- Makoto Ozawa (ORCID: https://orcid.org/0000-0002-7731-5321)
- Manabu Onuma (ORCID: https://orcid.org/0000-0001-8611-7506)
- Norikazu Isoda (ORCID: https://orcid.org/0000-0003-3480-988X)
- Hiroshi Ito (ORCID: https://orcid.org/0000-0003-2035-8870)
- Takahiro Hiono (ORCID: https://orcid.org/0000-0001-8897-3592)
- Lim Yik Hew (ORCID: https://orcid.org/0009-0004-2766-084X)
- Daiki Kobayashi (ORCID: https://orcid.org/0009-0007-0072-1042)
- Hiroki Takakuwa
- Yo Shimazu (ORCID: https://orcid.org/0009-0002-5668-8054)
Institutions
- Hokkaido University of Science (JP)
- Kagoshima University (JP)
- National Agriculture and Food Research Organization (JP)
- Kyoto Sangyo University (JP)
- National Institute for Environmental Studies (JP)
- Hokkaido University (JP)
- Kagoshima Prefectural Museum (JP)
- National Institute of Animal Health (JP)
- Tottori University (JP)
Publication Details
- Journal
- Pathogens
- Published
- 2025-09-21
- DOI
- https://doi.org/10.3390/pathogens14090951
- Primary Topic
- Influenza Virus Research Studies
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- Japan Agency for Medical Research and Development
- Environmental Restoration and Conservation Agency
- Ministry of Environment
- Japan Science and Technology Agency