Summary
- H5 highly pathogenic avian influenza viruses (HPAIVs) of the A/goose/Guangdong/1/1996 lineage have diversified into multiple clades, threatening wild birds and poultry worldwide.
- Clade 2.3.4.4b HPAIVs have been consistently isolated in Asia, Europe, and North America, highlighting the role of migratory birds in virus dissemination.
- Hokkaido, Japan experienced HPAIV outbreaks in winter due to bird migration, with H5N5 HPAIVs detected in crows, showing a genetic link to Europe.
- Concurrent circulation of genetically distinct H5N5 and H5N1 HPAIVs in crows suggests reassortment between viruses from different regions.
- Continuous monitoring and international cooperation are crucial to understand the global dynamics of HPAIVs and prevent their spread.
Summary: Highly pathogenic avian influenza viruses (HPAIVs) of the A/goose/Guangdong/1/1996 lineage have evolved into multiple clades, with clade 2.3.4.4b HPAIVs being prominent in Asia, Europe, and North America since 2016. Research conducted in Hokkaido, Japan during the winter seasons of 2021-2024 identified H5N5 HPAIV outbreaks in crows, highlighting the role of migratory birds in viral transmission. Genetic analysis revealed the origin of these viruses in Europe and their unique gene constellations, suggesting step-by-step bird migration from northern Eurasia. Continuous monitoring and collaboration between countries are crucial to understand the global dynamics of HPAIVs and prevent further spread.
The study isolated H5N1 and H5N5 HPAIVs from dead crows in Hokkaido, with the latter belonging to the G2a subgroup and sharing genetic similarities with HPAIVs detected in Europe. Cocirculation of genetically distinct HPAIVs within the crow population indicated potential reassortment events. Antigenic characterization suggested close antigenicity between H5N5 HPAIVs and other H5 HPAIVs despite genetic diversity. The research highlighted the need for rapid information sharing and global cooperation to combat the spread of HPAIVs.
The presence of H5N5 HPAIVs in Japan raises concerns, as infections in waterfowl are relatively unknown in the region. The study emphasized the importance of continuous monitoring and information sharing to track the spread of HPAIVs and implement preventive measures. Further investigation is required to understand the transmission dynamics and genetic evolution of H5N5 HPAIVs, with the ultimate goal of preventing future outbreaks.
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Infectious Diseases, Public Health & Prevention