2009年成都市流感活动情况及H3N2亚型流感病毒HA1基因特性分析

Hemagglutinin Gene of Influenza A(H3N2) Virus from Human Samples in the 2009 Influenza Epidemic in Chengdu

目的 分析2009年成都市流感流行情况,探讨甲3流感病毒（H3N2）亚型分离毒株的流行及HA1基因变异和进化。方法 MDCK细胞对咽拭子样品进行病毒分离鉴定,提取病毒核酸,用RT-PCR法扩增HA1基因,对H3N2分离株核酸及氨基酸序列进行亲缘关系分析。结果甲型流感H1N1、H3N2、甲1、B型流感病毒分离率分别为25.2%、7.2%、4.5%、1.5%,流感流行高峰为夏秋季。H3N2与同年疫苗株氨基酸序列比对,同源性为97.0%～98.8%,点突变率为1.8%～3.0%,在抗原决定簇及受体结合部位共有4个位点发生替换：160位N〉K、174位K〉R/N、189位K〉Q、277位R〉Q。部分毒株在160位插入糖基化位点,在181位出现糖基化位点缺失。结论 2009年成都市流感以甲型流感H1N1为主,甲1、甲3及B型流感病毒循环交替并存;H3N2基因特性发生改变,出现抗原漂移。

Objective To study the antigenic and genetic characteristics of influenza A（H3N2） virus in the 2009 influenza epidemics in Chengdu.Methods The influenza virus strains were isolated with MDCK cells from 4869 samples taken from the sentinel surveillance in 2009 in Chengdu.Hemagglutination inhibition（HI） and RT-PCR reaction tests were performed to guide the extraction of viral RNA from the culture fluid of the influenza A（H3N2） virus.The hemagglutinin gene was obtained by RT-PCR and sequenced.Results The separation rates of swine influenza H1N1,H3N2,H1N1,and B were 25.2%,7.2%,4.5%,and 1.5% respectively.The epidemic peaked in summer and autumn.Four amino acids changed in A,B,and D antigenic and receptor binding sites： site160N〉K,site174K〉R/N,site189K〉Q,site277RQ.Glycosylation sites were inserted to site160 or absent at site181 in some isolated strains.Conclusion Swine influenza H1N1 viruses dominated the 2009 Chengdu epidemic,with H3N2,H1N1,and B strains coexisting.The influenza A（H3N2） viruses had gene variations due to antigenic drift.