甘肃省人感染H7N9禽流感病毒基因组对比分析

Comparative analysis of influenza A(H7N9)virus genomes in human infection cases in Gansu

目的分析甘肃省发现的人感染H7N9禽流感病毒序列,对比高致病性禽流感(HPAI)和低致病性禽流感(LPAI)H7N9病毒的基因变异及分子进化特征,为疾病预防控制提供参考。方法对甘肃省2017年以来发现的人感染H7N9禽流感病毒进行基因组对比,并使用MEGA 7.0等软件分析其全基因组特征。结果6例人感染H7N9病例,均有活禽或其环境暴露史,共获得3株毒株:GS/19545、GS/27151和GS/23275。GS/19545和GS/27151为LPAI,GS/23275为HPAI。3株毒株的HA、NA基因均来自欧亚系的长三角支系。GS/23275的NP基因和广东省2017年分离的HPAI处于同一进化分支上,与GS/19545、GS/27151形成两个明显的分支。GS/23275的PB2基因与安徽省2015年从禽类体内分离的H9N2病毒亲缘关系较近。3株毒株的HA受体结合位点均发生G186V、S138A突变,NA蛋白茎部均发生68~72位点氨基酸缺失,在PA、PB1、PB2、M1、M2、NS1、NS2等蛋白中均发生相同氨基酸突变。结论甘肃省人感染H7N9禽流感病毒基因组发生了部分重要分子突变,可能导致其毒力增强,并具备潜在的人际传播能力。加强禽流感病毒基因特征研究分析,有助于从分子水平上监测病毒变异突变并对疫情进行科学防控。

Objective To analyze the sequence of avian influenza A(H7N9)virus detected in human infection cases in Gansu,compare the genetic variation and molecular evolution characteristics of highly and low pathogenic H7N9 viruses,and provide scientific reference for the prevention and control of human infection with avian influenza virus.Methods The genomes of H7N9 virus found in Gansu since 2017 were compared,and the whole genome characteristics were analyzed by MEGA 7.0 and other software.Results The 6 cases of human infection with H7N9 virus had history of live poultry or environmental exposures,and 3 virus strains were isolated,i.e.GS/19545,GS/27151 and GS/23275.The HA and NA genes of GS/19545,GS/27151 and GS/23275 were all from the Yangtze River Delta Branch of Eurasia.The NP gene of GS/23275 was in the same evolutionary branch with the highly pathogenic H7N9 virus from Guangdong in 2017,forming another distinct branch differed with the low pathogenic strains of GS/19545 and GS/27151.The results showed that the PB2 gene of GS/23275 was closely related to the H9N2 virus isolated from poultry in Anhui in 2015.G186 V and S138 A mutations occurred in HA receptor binding sites of three H7 N9 strains,68-72 amino acid deletion occurred in NA protein stems,and the same amino acid mutation occurred in PA,PB1,PB2,M1,M2,NS1,NS2 proteins.Conclusion Some important molecular mutations occurred in the genome of H7N9 virus detected in human infection cases in Gansu,which might lead to increased virulence of avian influenza virus and potential interpersonal transmission.Strengthening the research and analysis on the genetic characteristics of avian influenza virus might facilitate the surveillance for the mutation of the virus at molecular level and carry out effective prevention and control of the epidemic.