2006⁃2020年新疆分离的H3N2亚型流感病毒HA基因特征分析

Analysis of HA Gene Characteristics of H3N2 Subtype Influenza Virus Isolated from Xinjiang,China,2006–2020

分析新疆2006⁃2020年甲型H3N2流感病毒血凝素(Hemagglutinin,HA)基因的遗传变异特征。选取新疆2006年10月⁃2020年3月分离的32株H3N2流感毒株,进行核酸提取、HA基因扩增和测序,用CExpress软件进行拼接,MEGA⁃X软件进行数据整理,beast软件构建系统进化树,用P⁃epitope模型评估疫苗的有效性。新疆2006⁃2020年检测阳性样本中H3N2亚型在2006⁃2007、2010⁃2011、2012⁃2013、2014⁃2015、2016⁃2017、2019⁃2020年占比分别为77.78%、57.16%、64.53%、80.48%、87.35%、74.56%。H3N2流感病毒优势流行株2011年前以为A/Brisbane/10/2007类似株分支和A/Perth/16/2009(group1)分支为主,2011年后以3C分支为主。系统进化树分析显示,同一监测年度的流行株基本呈现集中分布。分子特征显示与疫苗株A/California/7/2004相比HA蛋白共有55个氨基酸位点变异,其中HA1和HA2分别占45和9个,HA1氨基酸的变异位点中28个位于抗原决定簇,5个抗原决定簇均发生变异,受体结合位点在135、137、225发生变异;2013⁃2020年RBS左侧壁发生N225D回复突变,128、138、193位存在回复突变分别为T⁃A⁃T、S⁃A⁃S、S⁃F⁃S,2014⁃2015年本地流行株与疫苗株A/Texas/50/2012相比A区、B区发生A138S、R142G、N145S、N128A、F159S突变,2015⁃2016年本地流行株与疫苗株A/Switzerland/9715293/2013相比A区、B区发生S138A、R140I、G142R、N144S、A128T、S159Y、K160T、V186G突变,2019⁃2020年本地流行株与疫苗株A/Kansas/14/2017相比A区、B区发生T135K、S137F、K144S、S159Y、K160T、N190D突变;糖基化位点自2006年10月⁃2020年3月变化增加,糖基化位点最多的集中在3C分支存在13个糖基化位点,3C分支均增加了45NSS糖基化位点,仅3C.2和3C.2a1分支存在158NYT且114NNS消失。新疆2006⁃2020年甲型H3N2流感病毒HA基因不断发生突变,出现了抗原漂移,部分流行株与当年推荐疫苗株匹配程度降低,流感网络实验室连续开展流感监测,有助于及早发现流感病毒的变异特征。

To analyze the genetic variation of the hemagglutinin(HA)gene of the influenza A H3N2 virus from 2006 to 2020 in Xinjiang,China.Thirty⁃two H3N2 influenza strains isolated in Xinjiang from October 2006 to March 2020 were selected for nucleic acid extraction,as well as amplification and sequencing of the HA gene.The latter was spliced using cexpress software.Data were sorted by mega⁃x software.Phylogenetic tree was constructed using beast software.The effectiveness of the vaccine was evaluated by the p⁃epitope model.Among the positive samples tested in Xinjiang,China from 2006 to 2020,H3N2 subtypes accounted for 77.78%,57.16%,64.53%,80.48%,87.35%and 74.56%,respectively,in 2006–2007,2010–2011,2012–2013,2014–2015,2016–2017 and 2019–2020.Before 2011,the dominant strains of the H3N2 virus in Xinjiang,China were mainly A/brisbane/10/2007⁃like and A/perth/16/2009(group 1).After 2011,the sequences were mainly of the 3C branch.Phylogenetic trees showed that the epidemic strains in the same monitoring year showed a centralized distribution.Compared with the vaccine strain A/California/7/2004,the HA protein had 55 variations in amino acid sites,of which HA1 and HA2 accounted for 45 and 9,respectively.Among the amino acid variation sites of HA1,28 were located in the antigenic determinant,and five antigenic determinants were mutated;135,137,225 mutations occurred at receptor binding sites.From 2013 to 2020,N225D reversion mutation occurred in the left wall of RBS.The reversion mutations were T⁃A⁃T,S⁃A⁃S,and S⁃F⁃S in 128,138,and 193.Compared with the vaccine strain A/Texas/50/2012,A138S,R142G,N145S,N128A,and F159S mutations occurred in the A and B regions of the local epidemic strain from 2014 to 2015.Compared with the vaccine strain A/Switzerland/9715293/2013,S138A,R140I,G142R,N144S,A128T,S159Y,K160T,and V186G mutations occurred in the local epidemic strain from 2015 to 2016.Compared with the vaccine strain A/Kansas/14/2017,T135K,S137F,K144S,S159Y,K160T,and N190D mutations occurred in the local epidemic strain from 2019 to 2020.The number of glycosylation sites increased from October 2006 to March 2020.The most glycosylation sites(13)were concentrated in the 3C branch.The latter had increased 45nss glycosylation sites,only the 3C 2 and 3C 2A1 branches had 158nyt,and 114nns disappeared.The HA gene of the influenza A H3N2 virus was mutated continuously from 2006 to 2020 in Xinjiang,China antigen drift was noted.The degree of matching between some epidemic strains and recommended vaccine strains decreased from 2006 to 2020.Continuous influenza monitoring in the influenza network laboratory is helpful to early detect the variation characteristics of influenza virus.