Isolation and genetic analysis of a novel triple-reassortant H1N1 influenza virus from a pig in China.

Influenza A viruses of subtype H1N1 have been reported widely in pigs in China, associated with clinical disease. These mainly include classical swine H1N1, avian-like H1N1, and human-like H1N1 viruses. In this study, we reported a novel triple-reassortant H1N1 virus (A/swine/Guangdong/1/2010) containing genes from the classical swine (NP, NS), human (PB1) and avian (HA, NA, M, PB2, PA) lineages, which was for the first time reported in China. Also, phylogenetic analysis further confirmed that five genes segments (NS, NP, PB2, PB1, PA) of the isolate were closely related to the novel reassortant H1N2 viruses isolated in China in 2006, while the other three (HA, NA, M) were closely related to avian-like H1N1 viruses in China. The isolation of triple-reassortant H1N1 influenza virus provides further evidence that pigs serve as emergence hosts or "mixing vessels", and swine influenza virus (SIV) surveillance in China should be given a high priority.