Objective In China, H9N2 avian influenza viruses were first reported in
chickens in Guangdong province in the mid-1990s. Subsequently, the
viruses spread to most regions nationwide, where they became panzootic
and endemic. Based on environmental surveillance of live poultry markets
in Anhui province from 2013 to 2018, a total of 33 representative
environmental isolates were selected and studied systematically. Methods
The genomic RNA of Anhui H9N2 isolates was subjected to RT-PCR
amplification followed by sequencing analysis. Results Thirty-three
strains were isolated from the embryonated eggs of
specific-pathogen-free chickens. Phylogenetic analysis indicated that
h9.4.2.5-like H9N2 viruses were predominant during 2013--2018 and
acquired multiple specific amino acid mutations that may have increased
their affinity for mammals and enhanced their infectivity and
transmissibility. Additionally, six internal genes of H9N2 clustered
together with the novel human-lethal reassortant viruses, such as low
pathogenicity H7N9, H10N8 and Anhui H5N6 viruses, and even HPAI H7N9.
Conclusion Because H9N2 viruses may be the donors of internal genes that
lead to the generation of novel reassortant viruses with enhanced
pathogenicity in Anhui province, continuous environmental surveillance
of live poultry markets, a key source of reassorted H9N2 and other avian
influenza viruses, is of great importance.