Evolutionary #lineage and #host origin influence #virulence and #mammalian adaptation of #H7N9 avian #influenza viruses
Abstract The H7N9 avian influenza virus (AIV) has posed a major global public health concern since its first detection in China in 2013 . Transmitted among wild birds and poultry , this virus has crossed the species barrier to infect humans , causing severe respiratory disease and high mortality . Although the widespread use of H7 vaccines has markedly reduced human infections , the ongoing circulation and adaptive evolution of the virus in poultry remain a serious threat . In this study, we analyzed three highly pathogenic H7N9 isolates collected in China in 2022, representing two hemagglutinin (HA) gene evolutionary lineages : Group.y.2.3 (isolate 229-4, chicken origin; isolate 782-2, quail origin) and Group.y.2.4 (isolate 621, quail origin). Pathogenicity was compared through phylogenetic analysis , molecular characterization, and infection experiments in both avian and mammalian models . Group.y.2.3 isolates displayed stronger replication and pathogenicity in chickens and mic...