2018-2019北京市门头沟区甲型H3N2流感疫情病毒HA基因分析

目的分析2018-2019北京市门头沟区流感疫情中甲型H3N2流感病毒的HA基因特性,了解其与WHO推荐的疫苗株和同时期北京其他地区的毒株匹配情况。方法选取门头沟区2018-11/2019-01多起流感疫情中的13株甲型H3N2流感病毒,进行HA基因扩增和测序,并从全球共享禽流感数据库(GISAID)上下载北京其他地区同时间段H3N2流感病毒HA基因序列,运用MEGA-X软件分析HA的分子特征,并构建系统进化树。结果2018-11/2019-01北京市门头沟区和北京市其他地区的数据显示,H3N2流行株以3C.2a.1b和3C.3a两个亚分支为主。系统进化树分析显示3C.2a.1b亚分支同WHO2018-2019推荐疫苗株3C.2a.1进化距离比较近,但与3C.3a进化距离较远。分子特征显示,没有发现氨基酸序列的丢失与插入。在抗原决定簇区域,3C.2a.1b亚分支和3C.2a.1比对有3处氨基酸位点发生变异;3C.3a亚分支和3C.2a.1比对有10处氨基酸位点发生变异。结论引起流感疫情的毒株3C.2a.1b与2018-2019 WHO推荐疫苗株匹配,3C.3a与2019-2020WHO推荐疫苗株匹配。应加强开展流感分子生物学监测力度。分析病毒基因特性和构建进化树,对流感的防控有重要意义。

Genetic analysis of the hemagglutinin(HA)gene of influenza A(H3N2)virus isolated from outbreaks in the Mentougou District of Beijing From 2018 to 2019

Objective To analyze the genetic characteristics of the HA gene of influenza A(H3N2)virus isolated from influenza outbreaks in Mentougou District from 2018-2019,and compare it with the WHO vaccine strain and strain in other districts of Beijing in the same period.Methods 13 strains of H3N2 virus isolated from successive influenza outbreaks in Mentougou District from November 2018 to January,2019 were selected,and HA gene were amplified and sequenced.The other sequences of HA gene of influenza(H3N2)virus strains isolated from Beijing in the same period were obtained from the GISAID database.The software MEGA-X was used to analyze the molecular characteristics of the HA gene.Phylogenetic tree was constructed by using the neighbor-joining method.Results The majority of Strains of influenza A(H3N2)virus belonged to the phylogenetic subclade 3 C.2 a1 b and clade3 C.3 a.The evolutionary distance of Subclade 3 C.2 a1 b was close to the WHO vaccine strain(A/Singapore/INFIMH-16-0019/20163 C.2 a),but far from with the WHO vaccine strain(A/Kansas/14/20173 C.3 a).Molecular characteristics analysis indicated that the loss and insertion of amino acid sequences were not found.In epitopes of the HA protein,mutations of Subclade 3 C.2 a1 b occurred in 3 amino acid compared with Subclade 3 C.2 a1,mutations of Subclade 3 C.3 a occurred in 10 amino acid compared with Subclade 3 C.2 a1.Conclusion The Subclade 3 C.2 a1 b and 3 C.3 a virus could match with WHO vaccine strains A/Singapore/INFIMH-16-0019/2016 and A/Kansas/14/2017,respectively.Molecular biological monitoring of influenza should be strengthened.It is important to analyze gene characteristics of virus and construct phylogenetic tree for the prevention and control of influenza.