2022-2023年长沙市活禽市场H9N2亚型禽流感病毒遗传特征分析OA

This study analyzed the genetic characteristics of the hemagglutinin(HA)and neuraminidase(NA)genes of H9N2 subtype avian influenza virus(AIV)in live poultry markets(LPMs)in Changsha City during 2022-2023,to provide laboratory data to facilitate control of H9N2 subtype AIV outbreaks.A total of 809 environmental and poultry samples were collected from Changsha LPMs.Real-time fluorescence RT-PCR was used to detect influenza A virus and H9 subtype nucleic acids.Full-length gene amplifi-cation and sequencing were performed on H9-positive samples.Bioinformatics software was used for sequence alignment and genetic feature analysis.Nucleic acid detection revealed a 64.15%positivity rate for environmental AIV,and H9 showed the highest overall positivity rate(48.08%).Mixed infections exhibited the highest overall positivity rate of 5.07%for H5+H9.Genetic evolution analysis revealed that 29 isolates belonged to the B4.7.2 lineage,and five belonged to the B4.7.3 lineage,according to HA gene analysis.All NA genes belonged to the Y280-like subclade of the Eurasian lineage and showed close phylogenetic relationships with the candidate vaccine strain A/Anhui-Lujiang/39/2018.The HA protein cleavage site was PSRSSRGLF,in agreement with low pathogenic avian in-fluenza virus(LPAIV)characteristics.However,the presence of mutations Q226L(100%),I155T/N(17.65%/82.35%),and G192R(100%)suggested potential mammalian adaptation.The NA protein stem region exhibited a deletion at positions 63-65,but no muta-tions were observed at key drug resistance sites.Glycosylation site analysis revealed six conserved sites(29,141,298,305,313,and 492),whereas sites 105,145,206,and 218 were absent with respect to some reference strains,and site 313 was newly added.Antigenic site analysis revealed that 61.11%(11/18)of HA antigenic sites underwent mutations potentially leading to antigenic changes.Although H9N2 AIV from Changsha LPMs was classified as LPAIV,it exhibited mammalian adaptation mutations and anti-genic drift.Therefore,ongoing monitoring of its public health risks is necessary.