上海市闵行区甲型H1N1流感病毒株变异分析

Analyzing on variation of influenza A(H1N1) in Minhang district in Shanghai

目的:了解上海市闵行区人群中甲型H1N1流感病毒株基因特性及抗原变异情况,为甲型H1N1流感防控提供科学依据。方法:采集2009年8月-2011年3月闵行区哨点医院流感样患者鼻咽拭子标本,Real-time RT-PCR鉴定流感病毒亚型,犬肾细胞(MDCK)培养分离流感病毒,血凝抑制试验(HI)确定流感病毒型与亚型。对部分甲型H1N1流感病毒株进行血凝素(HA)、病毒聚合酶(PB2)片段全基因测序,分析基因和氨基酸位点变异情况。结果:闵行区于2009年8月-2010年3月发生第一波甲型H1N1流感疫情,共报告甲型H1N1流感确诊病例232例,占流感病例总数的54.33%。2010年12月-2011年3月发生第二波甲型H1N1流感疫情,共报告甲型H1N1流感确诊病例71例,占流感病例总数的62.83%。HA进化树分析发现,第二波分离的甲型H1N1流感毒株与大多数2009年第一波大流行分离毒株不位于同一主干上,说明HA基因发生了一定程度的变异;HA蛋白氨基酸位点分析显示,部分毒株在抗原决定位点上发生了变异。PB2蛋白氨基酸序列分析显示,第627位和701位点分别是谷氨酸和天冬氨酸,仍为禽源流感病毒PB2蛋白氨基酸位点,但第677位点出现E677G突变。结论:2011年冬春季闵行区人群中甲型H1N1流感流行毒株与2009年北美流行株比较已经有一定变异,出现了一些抗原漂移和适应性进化。

Objective：To investigate the genetic and antigenic variation of influenza A（H1N1） in Minhang area,and provide evidence for the prevention and control of the disease.Methods： Nasopharyngeal swabs from influenza-like-illness were collected in Sentinel hospitals in minhang from August 2009-March 2011,and detected by real-time RT-PCR.Viruses were isolated with MDCK cells and identified with haemagglutination inhibition test（HI）.HA and PB2 genes of partial influenza A（H1N1） virus were sequenced,to analysis the variation on genes and amino acid sites.Results： The first outbreaks of influenze A（H1N1） occurred in August 2009-March 2010,232 cases of influenza A（H1N1） were reported,the proportion of influenze A（H1N1） cases among all patients was 54.33%.The second outbreaks of influenze A（H1N1） occurred in december 2010-March 2011,71 cases of influenza A（H1N1） were reported,the proportion of influenze A（H1N1） cases among all patients was 62.83%.The HA phylogenetic tree of influenza A（H1N1） showed that,the viruses isolated from first outbreaks of influenze A（H1N1） was not in the same trunk with the second,Variation of HA occurs to some extent.The analysis of amino acid sites on HA showed that,the antigenic site of some strains were changed during the second epidemic process.Analysis on the amino acid of PB2 protein showed the residues at the positions 627 and 701 were Glutamic acid and Aspartic acid respectively,which were the amino acid site of avian flu PB2 protein,but the mutation of residues were E677G.Conclusion： Variation occurs in Minhang district between the viruses strains isolated from causative influenze H1N1 in the spring season of 2011 from the pandemic influenza in North America,and antigenic drift strains and adaptive evolution appeared.