EMERGENCE OF AVIAN H1N1 INFLUENZA-VIRUSES IN PIGS IN CHINA

Avian influenza A viruses from Asia are recognized as the source of ge nes that reasserted with human viral genes to generate the Asian/57 (H 2N2) and Hong Kong/68 (H3N2) pandemic strains earlier in this century. Here we report the genetic analysis of avian influenza A H1N1 viruses recently isolated from pigs in southern China, a host suspected to ge nerate new pandemic strains through gene reassortment events. Each of the eight gene segments was of avian origin. Phylogenetic analysis ind icates that these genes form an Asian sublineage of the Eurasian avian lineage, suggesting that these viruses are an independent introductio n into pigs in Asia. The presence of avian influenza viruses in pigs i n China places them in an optimal position for transmission to humans and may serve as an early warning of the emergence of the next human i nfluenza virus pandemic.