Emergence of novel reassortant H3N2 influenza viruses among ducks in China.

During 2006-2009 influenza virus surveillance, three H3N2 viruses were isolated from ducks in Central China. Sequence and phylogenetic analyses revealed that most segments of these three isolates had high identity with H3N2 swine isolates in South China. However, for M, the three viruses, along with H1N1 swine isolates of North America, formed a cluster; for PB2, two of these isolates fell into the cluster of the H5N1 duck isolates, indicating a reassortment among H3N2, H1N1 swine viruses and H5N1 avian virus. The emergence of H3N2 virus with incorporation of an H5N1 virus gene raises new concerns about the generation of novel viruses that could affect humans.