12.08.2012

Qiao et al. (2012) Journal of General Virology

Both H9N2 avian influenza and 2009 pandemic H1N1 viruses (pH1N1) are able to infect humans and swine, which has raised concerns that novel reassortant H9 viruses with pH1N1 genes might be generated in these hosts by reassortment. Researchers from USA and China, generated 2 reassortant H9 viruses (H9N2/CA09 and H9N1/CA09) in the background of the pH1N1 A/California/04/2009 (CA09) virus by replacing either both HA and NA genes or only the HA gene with respective genes from the A/quail/Hong Kong/G1/1997 (H9N2) virus, and evaluated their replication, pathogenicity and transmission in chickens and pigs compared to the parental viruses. Chickens that were infected with the parental H9N2 and reassortant H9 viruses seroconverted. The parental H9N2 and reassortant H9N2/CA09 transmitted to sentinel chickens, but the H9N1/CA09 did not. The parental H9N2 replicated poorly and did not transmit in pigs; whereas both H9N2/CA09 and H9N1/CA09 viruses replicated and transmitted efficiently in pigs, similar to the pH1N1. The results demonstrated that reassortant H9 viruses with pH1N1 genes enhance replication and transmissibility in pigs when compared to the parental H9N2 virus, indicating that they might pose a threat for humans if such reassortants arise in swine.