2015-2017年浙江省衢州市H3N2亚型流感病毒血凝素基因分子进化特征分析

Molecular characteristics of hemagglutinin gene of influenza A (H3N2) virus in Quzhou,2015-2017

目的了解浙江省衢州市2015-2017年H3N2亚型流感病毒血凝素(HA)基因分子进化特征,为流感防控提供科学依据。方法选取衢州市2015-2017年分离到的H3N2亚型流感病毒18株,通过RT-PCR扩增病毒HA基因片段并测序,采用生物信息学软件分析其分子进化特征。结果 18株H3N2亚型流感病毒HA基因的核苷酸和氨基酸同源性分别为97.36%~100.00%和96.76%~100.00%,与同年度疫苗株HA基因的核苷酸平均遗传距离分别为0.008 2、0.007 1和0.011 2,氨基酸平均遗传距离分别为0.009 2、0.003 1和0.010 0。分离株的HA基因分支从3C.3a转变为3C.2a支系,其HA氨基酸序列与同年度疫苗株比较,变异位点共涉及HA蛋白的5个抗原表位(A、B、C、D和E区),2个受体结合位点(T131K、T135N/K),6个潜在糖基化位点(122NES、126NWT、133NGT、135NSS、144NSS、158NYT)。结论 2015-2017年衢州市H3N2亚型流感病毒可能出现了抗原漂移,当前疫苗株A/Hong Kong/4801/2014的免疫效果需重新评估。

Objective To understand the molecular evolutional characteristics of hemagglutinin（HA）gene of influenza A（H3N2）virus in Quzhou,Zhejiang province,from 2015 to 2017 and provide scientific evidence for the prevention and control of influenza.Methods A total of 18 influenza A（H3N2）virus strains isolated in Quzhou from 2015 to 2017 were selected. The full-length of HA genes were amplified by RT-PCR and sequenced. Bioinformatics software was used to analyze the sequences.Results The homologies of nucleotide and amino acid of 18 influenza A（H3N2）strains were 97.36%-100.00% and 96.76%-100.00%,respectively. The average genetic distances of the HA genes between the vaccine strains and the isolated strains were 0.008 2,0.007 1 and 0.011 2 at nucleotide levels,and 0.009 2,0.003 1 and 0.010 0 at amino acid levels,respectively. The HA genetic clades of the isolated strains had transformed from 3 C. 3 a to 3 C. 2 a. The amino acid sites of the isolated strains had changed compared with the vaccine strain A/Switzerland/9715293/2013 and A/Hong Kong/4801/2014,there were 5 antigenic epitopes（A,B,C,D and E regions）,2 receptor binding sites（T131 K,T135 N/K）and 6 potential glycosylation sites（122 NES,126 NWT,133 NGT,135 NSS,144 NSS,158 NYT）involved.Conclusion The results revealed that the antigenic drift might occur in influenza A（H3N2）virus strains isolated in Quzhou from 2015 to 2017,suggesting that the efficacy of the vaccine strain A/Hong Kong/4801/2014 need to be re-evaluated.