Novel reassortant highly pathogenic H5N6 avian influenza viruses in poultry in China

• Highly pathogenic H5N6 influenza viruses were isolated from poultry in eastern China.
• They were novel reassortant viruses that replicated in mice without prior adaptation.
• Surveillance is needed because of the importance of poultry in H5N6 reassortment.

We characterized two novel highly pathogenic H5N6 influenza viruses isolated from Chinese poultry in 2013. Genomic analysis showed that both isolates were reassortants, and derived their genes from H5 and H6 subtype viruses found in poultry in China. The virulence of the two isolates was examined in chickens and mice, and both isolates were found to be highly pathogenic in chickens and only moderately virulent for mice. Our results show that continued circulation of these viruses could endanger both avian species and humans.