The Origin of Internal Genes Contributes to the Replication and Transmission Fitness of H7N9 Avian Influenza Virus
Joe James, Sushant Bhat, Sarah K. Walsh, Thusitha K. Karunarathna, Jean-Rémy Sadeyen, Pengxiang Chang, Joshua E. Sealy, Sahar Mahmood, Benjamin C. Mollett, Marek J. Slomka, Sharon M. Brookes, Munir Iqbal
Abstract
H9N2 avian influenza viruses (AIVs) are enzootic in poultry in different geographical regions. The internal genes of these viruses can be exchanged with other zoonotic AIVs, most notably the A/Anhui/1/2013-lineage H7N9, which can give rise to new virus genotypes with increased veterinary, economic and public health threats to both poultry and humans. We investigated the propensity of the internal genes of H9N2 viruses (G1 or BJ94) in the generation of novel reassortant H7N9 AIVs. We observed that the internal genes of H7N9 which were derivative of BJ94-like H9N2 virus have a fitness advantage compared to those from the G1-like H9N2 viruses for efficient transmission among chickens. We also observed the generation of novel reassortant viruses during chicken transmission which infected and replicated efficiently in human cells. Therefore, such emergent reassortant genotypes may pose an elevated zoonotic threat.