2012—2017年杭州地区甲型H3N2流感病毒HA和NA基因遗传进化分析

Genetic evolution of influenza A ( H3N2) virus in Hangzhou between 2012 and 2017

目的了解2012—2017年杭州地区甲型H3N2流感病毒的流行情况以及血凝素(HA)基因和神经氨酸酶(NA)基因的遗传进化特征。方法收集2012年1月至2017年12月间杭州地区流感样病例12185例,实时RT-PCR检测甲型H3N2流感病毒,同时选取部分甲型H3N2流感病毒阳性样本,用特异性引物扩增HA和NA基因,进行基因测序并分析其遗传进化特征。结果自2012年以来,杭州地区每年都有甲型H3N2流感病毒的流行。不同年龄段人群发病率存在统计学差异,趋势性卡方检验发现,随着年龄增长,发病率显著提高(Z=81.039,P<0.05)。2012年以来,杭州地区流行的甲型H3N2流感病毒主要属于3C.3a和3C.2a两个进化簇。HA和NA基因的序列一致性均为96.7%~100%,但在多个抗原位点发生了突变。结论甲型H3N2流感病毒在杭州地区流感流行中具有重要地位。2012—2017年,杭州地区甲型H3N2流感病毒抗原变异明显,但目前并未发现耐药株的出现和流行。

Objective To analyze the prevalence of influenza A ( H3N2 ) virus in Hangzhou between 2012 and 2017 and to investigate the genetic variations in hemagglutinin ( HA ) and neuraminidase (NA). Methods Throat swab samples were collected for viral isolation from 12 185 patients with suspected influenza in Hangzhou area from January 2012 to December 2017. Influenza virus subtypes were identified by real-time RT-PCR. H A and NA genes of some isolated Influenza A ( H3N2) viruses were amplified with specific primers and then analyzed by sequencing and phylogenetic analysis. Results Influenza A ( H3N2 ) virus was the predominant subtype circulating in Hangzhou during 2012 to 2017. It caused high morbidity in elderly people ( Z = 81.039 , P<0. 05 ). Most of the isolated influenza A ( H3N2 ) viruses belonged to the phylogenetic clades of 3C. 3a and 3C. 2a. These vinises shared a homology of 96. 7%-100% in nucleotide sequences of both HA and NA genes, but possessed several HA and NA mutations in antigenic sites. Conclusions Influenza A ( H3N2) virus was an important, pathogen causing influenza epidemics in Hangzhou during 2012 to 2017. HA and NA genes showed many mutations in antigenic sites. No drug resistant virus was reported.