Novel emerging reassortant H6 avian influenza viruses with internal genes from G57 genotype of H9N2 pose potential zoonotic risk

The H6N2 isolate displayed dual receptor binding affinity for both avian-like and human-like receptors, whereas the five H6N1 viruses showed no detectable receptor binding affinity under the assay conditions <i>in vitro</i>. Reverse-genetics reassortant assay further revealed that the H6N1 HA itself possesses intrinsic dual receptor binding affinity. Furthermore, these H6 isolates exhibited high virulence in mice, and induced obvious respiratory symptoms in chickens, with efficient transmission among birds.

Collectively, our findings demonstrate that H6 AIVs carrying the G57 H9N2 internal gene constellation are actively circulating in chicken populations and pose a substantial threat to poultry health, underscoring their potential risk to public health and the need for continued surveillance at the poultry-human interface.</p>