2018年上海市活禽市场6株H9N2亚型禽流感病毒全基因进化分析

为了解上海市活禽市场H9N2亚型禽流感病毒(AIV)分离株的遗传变异情况,本研究对2018年分离的6株H9N2AIV的8个基因片段进行PCR扩增、克隆和测序,并对获得的HA和NA基因序列进行同源性和关键位点分析。结果显示:6个分离株的HA裂解位点均为RSSR↓GLF,符合低致病性AIV的分子特征;并对6株分离株HA基因分析了糖基化位点;受体结合位点除198位、202位和203位有变异外,其他位点均保守;226位氨基酸均为L,因此具有与哺乳动物唾液酸α2-6受体结合的特征。此外也对NA基因红细胞结合位点,活性中心以及抗原决定簇进行了分析,在红细胞结合位点403位发生突变,在活性中心(同时为抗原决定簇)143位发生突变,这6株病毒其余位点均保守。HA基因进化树显示,上述6株分离株均属于近几年在中国鸡群中流行的Y280分支。从8个基因片段组成方式分析这6个毒株属于G57基因型。以上研究为H9N2亚型AIV的防控和疫苗研制提供了科学参考。

Phylogenetic Analysis of Six H9N2 Subtype Avian Influenza Viruses from Shanghai Live Poultry Markets in 2018

To understand the genetic variation of H9N2 subtype Avian influenza virus (AIV) in Shanghai live poultry markets,all eight genes of six isolates obtained in 2018 were amplified,cloned and sequenced for analyzing the homology and key sites of these HA and NA genes.These isolates had a common motif RSSR↓GLF at the cleavage site,indicating their lentogenic pathotypes.Glycosylation sites were also analyzed on their HA genes.Receptor binding sites were conservative except mutations on the 198th,202th and 203th sites.The 226th amino acid was L,which had the characteristics of binding to mammalian sialic acid α2-6 receptor.The hemadsorbing sites,active center and antigenic determinants in the NA protein from six isolates were also analyzed for their variations.Mutations at position 403 on the HBS and position 143 on the active center were observed in NA proteins of these six isolates.Phylogenetic analysis of HA genes showed that all isolates belonged to the branch of Y280,which had been prevalent in China among chick flocks in recent years.Six strains belonged to G57 genotype according to the combination of all eight segments.These data provided a reference for the prevention and control of H9N2 subtype AIV and vaccine development.