Integrated approaches to explore temporal-spatial changes in gene reassortment of highly pathogenic avian influenza A(H5) virus in Eurasia, 2000–2023

The global circulation of the Goose/Guangdong/1996-lineage (Gs/Gd)-descended H5 viruses is highly pathogenic and has led to diversification of the HA gene through gene reassortment with low pathogenic avian influenza viruses (LPAIV), increasing their adaptability to different hosts. Our study aimed to investigate the spatial and temporal dynamics of reassortment events and identify the environmental drivers associated with the ecological niche of the gene reassortment. The complete AIV sequence database was curated to identify the global genotype distributions of HPAIV since the emergence of Gs/Gd H5N1 in 1997. The three-stage study design was developed to identify the gene reassortment hotspots (RA-hotspots) of HPAIV H5 and to examine the association between RA-hotspots and different environmental risk factors. From 1997 to 2023, HPAIV H5 subtype exhibited increasingly complex genetic exchanges, with a total of 136 genotypes identified in this study. Three distinct waves were observed from mono-genotype-dominant (2000–2013) to multi-genotypic co-circulation (2014–2021), followed by regional endemicity (2022–2023). The matched-pair study found that bird species in the orders Anseriformes, Charadriiformes, and Passeriformes are significantly positively associated with RA-hotspots. The dynamic changes in H5 HPAIV genotypes are consistent with the transition of environmental drivers from waterfowl to landfowl, highlighting the importance of targeted surveillance to facilitate the development of mitigation strategies.