2017年江苏省H3N2流感病毒血凝素与神经氨酸酶分子特征及耐药性分析

Drug resistance and molecular characteration of hemagglutinin and neuraminidase for influenza A H3N2 viruses

目的流行性感冒(简称流感)耐药性监测目前已成为流感防控中的一项重要组成部分。文中旨在分析江苏省2017年H3N2亚型流感病毒基因变异及耐药性情况。方法从江苏省13个流感监测点流感毒株中选取17株H3N2亚型毒株,其中12株为2017年夏季高峰期分离株,4株为非高峰期分离株,1株为2016年度分离株(作为1株参考株)。采用逆转录聚合酶链反应(RT-PCR)对H3N2亚型流感毒株进行序列测定,从全球共享流感序列网站GISAID下载构建甲型H3N2亚型流感毒株HA(血凝素)系统进化树的骨架参考序列,使用MAGE7.0软件进行序列比对和系统进化分析。通过神经氨酸酶(NA)抑制试验,分析病毒耐药情况。结果16株病毒HA和NA基因核苷酸相似性分别为98.9%~99.6%、99.2%~99.3%,同源性较高。HA进化树分析显示,16株分离株中15株位于3C.2a分支,13株病毒3个C3.2a1分支关键位点(N171K、I406V和G484E)未发生变化,另外3株毒株关键位点发生变异,1株毒株发生该标志性氨基酸变异,1株毒株发生(N121K、T135K)的免疫相关突变。与2017-2018年度疫苗株推荐株A/HongKong/4801/2014相比,16株分离株抗原位点突变包括:A138S 1株,R142K 2株,R142K、R261Q 9株,R142KS144R、R261Q 1株,R142K、S144K、R261Q 1株。16株病毒的NA片段分析未发现NA耐药位点。基因型和表型分析表明,16株H3N2亚型流感毒株对抗流感药物奥司他韦及扎那米韦均敏感,均发现与M2基因耐药有关A30T、S31N分子位点的改变。结论2017年江苏H3N2亚型流行株HA和NA基因表现出异质性特点及发生基因重配现象,随着H3N2流感病毒变异持续发生,应密切监测病毒遗传进化和耐药基因的变化情况。

Objective To analyze the variations and drug resistance of influenza A(H3 N2)viruses in Jiangsu Province in2017,and provide evidence for prevention and control strategies on influenza.Methods Reverse transcription polymerase chain reaction(RT-PCR)was used for the sequencing of H3 N2 subtype influ-enza strains.The influenza reference sequences were obtained from the global shared influenza site GISAID.The sequence alignment and phylogenetic analysis were performed using MAGE7.0 software.Viral resistance was analyzed by a neuraminidase inhibition assay.Results The H3 N2 subtype influenza isolates and vaccine strains belonged to the 3 C.2 a branch of the H3 subtype.Some of the strainsshowed amino acid mutations on the immune-related sites named N121 K,T135 K and N171 K.The isolates were sensitive to the flu drugs oseltamivir and zanamivir.Conclusion The H3 N2 epidemic strains in Jiangsu have genetic recombination within subtypes and are still sensitive to neuraminidase inhibitors.As the H3 N2 influenza virus mutations continue,a close monitoring of the viral ge-netic evolution and the drug resistant genes should be guaranteed.