Diversity, evolution and population dynamics of avian influenza viruses circulating in the live poultry markets in China

- A high diversity and prevalence of AIVs was found in LPMs in all surveyed regions.
- Frequent reassortment of AIVs between different subtypes and hosts were observed.
- H5N6 reassortant with a set of H9N2 internal genes was found in all three regions.
- A dynamic shift in viral genetic diversity over the course of a one year occurred.

Live poultry markets (LPMs) are an important source of novel avian influenza viruses (AIV). During 2015-2016 we surveyed AIV diversity in ten LPMs in Hubei, Zhejiang and Jiangxi provinces, China. A high diversity and prevalence of AIVs (totaling 12 subtypes) was observed in LPMs in these provinces. Strikingly, however, the subtypes discovered during 2015-2016 were markedly different to those reported by us in these same localities one year previously, suggesting a dynamic shift in viral genetic diversity over the course of a single year. Phylogenetic analyses revealed frequent reassortment, including between high and low pathogenic AIV subtypes and among those that circulate in domestic and wild birds. Notably, the novel H5N6 reassortant virus, which contains a set of H9N2-like internal genes, was prevalent in all three regions surveyed. Overall, these data highlight the profound changes in genetic diversity and in patterns of reassortment in those AIVs that circulate in LPMs.