Isolation and genetic characterization of multiple genotypes of both H5 and H7 avian influenza viruses from environmental water in the Izumi plain, Kagoshima prefecture, Japan during the 2021/22 winter season

Kosuke Okuya; Mana Esaki; Kaori Tokorozaki; Taichi Hasegawa; Makoto Ozawa

doi:10.1016/j.cimid.2024.102182

Isolation and genetic characterization of multiple genotypes of both H5 and H7 avian influenza viruses from environmental water in the Izumi plain, Kagoshima prefecture, Japan during the 2021/22 winter season

Comp Immunol Microbiol Infect Dis. 2024 Apr 15:109:102182. doi: 10.1016/j.cimid.2024.102182. Online ahead of print.

Authors

Kosuke Okuya¹, Mana Esaki², Kaori Tokorozaki³, Taichi Hasegawa⁴, Makoto Ozawa⁵

Affiliations

¹ Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima 890-0065, Japan; Joint Graduate School of Veterinary Medicine, Kagoshima University, Kagoshima 890-0065, Japan.
² Joint Graduate School of Veterinary Medicine, Kagoshima University, Kagoshima 890-0065, Japan.
³ Kagoshima Crane Conservation Committee, Izumi 899-0208, Japan.
⁴ Matsuoka Research Institute for Science, Koganei 184-0003, Japan.
⁵ Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima 890-0065, Japan; Joint Graduate School of Veterinary Medicine, Kagoshima University, Kagoshima 890-0065, Japan; Kagoshima Crane Conservation Committee, Izumi 899-0208, Japan. Electronic address: mozawa@vet.kagoshima-u.ac.jp.

PMID: 38640701
DOI: 10.1016/j.cimid.2024.102182

Abstract

In the 2021/22 winter, one H5N1 and nine H5N8 high pathogenicity avian influenza viruses (HPAIVs) of clade 2.3.3.4b were isolated from the water in crane roosts on the Izumi plain, Japan. Additionally, we isolated low pathogenicity avian influenza viruses (LPAIVs) of five subtypes: H1N1, H4N2, H4N6, H7N7, and H10N4. H5N8 HPAIVs belonging to the G2a group were isolated throughout winter, whereas H5N1 HPAIV belonging to the G2b group were isolated only in early winter. These findings suggest co-circulation of both G2a and G2b HPAIVs in early winter. Although two H7N7 LPAIVs were isolated from cranes' roost water collected on the same day, the gene constellations of the two isolates were clearly different, indicating the contemporary invasion of at least two different genotypes of H7N7 LPAIVs in the Izumi plain. This study underscores the importance of monitoring both HPAIVs and LPAIVs to understand avian influenza virus ecology in migratory waterfowl populations.

Keywords: Environmental water; High pathogenicity avian influenza virus; Multiple genotypes; Phylogenetic analysis.