Genetic analysis of H3N2 avian influenza viruses isolated from live poultry markets and poultry slaughterhouses in Shanghai, China in 2013.

Five H3N2 avian influenza viruses (AIVs) were isolated from live poultry markets (LPMs) and poultry slaughterhouses in Shanghai, China in 2013. All viruses were characterized by whole-genome sequencing with subsequent genetic comparison and phylogenetic analysis. The hemagglutinin cleavage site of all viruses indicated that the five strains were low-pathogenic AIVs. Phylogenetic analysis of all eight viral genes showed that the five H3N2 viruses clustered in the Eurasian lineage of influenza viruses. The eight genes showed evidence of reassortment events between these H3 subtype viruses and other subtype viruses, especially H5 and H7 subtypes, probably in pigeons, domestic ducks, and wild birds. These findings emphasized the importance of AIV surveillance in LPMs and poultry slaughterhouses for understanding the genesis and emergence of novel reassortants with pandemic potential.