2007-2009年郴州市H3N2亚型流感病毒HA1基因特性研究

Molecular Characterization of Hemagglutination Gene of Influenza H3N2 Virus in Chenzhou from 2007 to 2009

目的了解2007-2009年郴州市H3N2亚型流感病毒流行情况及血凝素基因变异特征。方法 按时间先后顺序随机选择2007-2009年流感病原学监测中分离到的H3N2亚型毒株8株,提取病毒核糖核酸(RNA),采用RT-PCR法扩增病毒HA1基因,纯化产物进行核苷酸序列测定并推导其氨基酸序列进行基因特性分析。结果H3N2亚型流感病毒在2007年为优势株,2008-2009年相对H1N1亚型流感病毒为弱势株;2007年分离株与该年疫苗株(A/Wisconsin/67/2005)比较,变异位点主要为G50E、S138A、K140I、R142G、N144D和L157S,抗原性发生了漂移;2008年分离株与2008-2009年疫苗株(A/Brisbane/10/2007)比较,变异位点主要为R142G、L157S;2009年分离株与该年疫苗株比较,变异位点主要为L157S、K173Q,2008-2009年分离株与该年疫苗株比较未发生明显变异。结论郴州市2007年H3N2亚型流感病毒HA1发生了明显变异,H3N2流感病毒较活跃,当年生产的疫苗预防效果较差;2008-2009年H3N2亚型流感病毒HA1与该年度疫苗株相比未发生明显变异,人群对其建立较好的免疫屏障,这是郴州市2008-2009年H3N2亚型流感病毒活动水平较低的主要原因。

Objective To understand the prevalence and genetic characteristics of hemagglutinin of influenza H3N2 virus in Chenzhou during the period of 2007～2009. Methods Eight H3N2 strains isolated were selected according to different time phases.RNAs were extracted and their HA1 genes were amplified by RT-PCR.The purified PCR products were sequenced and analyzed. Results Influenza H3N2 virus was dominant in Chenzhou in 2007,but as compared with influenza H1N2 virus,it was weaker during the period of 2008～2009.As compared with the vaccine strain（A/Wisconsin/67/2005） in 2007,the variation sites of influenza strains isolated in 2007 were G50E,S138A,K140I,R142G,N144D and L157S.There was a change of amino acid sequence of HA1.But as compared with the vaccine strain（A/ Brisbane/10/2007） in 2008～2009,the variation sites of influenza strains in 2008 were R142G and L157S,the variation sites of influenza strains in 2009 were L157S and K173Q.As compared with the vaccine strain,there was no significant variation observed in the amino acid sequence of HA1 in 2008～2009. Conclusions HA1 gene variation of influenza H3N2 viruses in Chenzhou in 2007 was recorded.The H3N2 subtype vaccine strain had an effective protection,which was the main cause leading to the spread of influenza.The amino acid sequence of HA1 had no distinct variation and the vaccine provided enough protection,which was the cause that the influenza H3N2 had lower activity among the population in Chenzhou during the period of 2008～2009.