2009-2011年杭州地区甲型H1N1流感病毒神经氨酸酶基因的遗传进化分析

Genetic evolution of the novel influenza A(H1N1) virus neuraminidase in Hangzhou,Zhejiang

目的了解2009年7月以来杭州地区甲型H1N1流感病毒神经氨酸酶基因（NA）的变异情况,分析其遗传进化特征。方法在流行季节采集发热病人咽拭子样本,经病毒分离培养及亚型鉴定后,用特异性引物扩增NA基因,测序并分析其遗传进化特征。结果 2009年7月至2011年3月,共检测监测样本1 898份,流感病毒阳性率为37.9%。期间经历了两次甲型H1N1流感病毒流行高峰。各时间段分离株间NA基因高度同源,序列相似性97.9%~100%,但2010/2011年流行株在进化树上分为两支,且与2009/2010年流行株遗传距离相对较远。进一步分析后发现,虽然耐药位点、酶活性位点及其附近氨基酸相对保守,但多个氨基酸变异发生于抗原决定簇上,且增加了NA蛋白茎部第42位糖基化位点。结论结果预示着酶抑制剂类药物对预防和治疗甲型H1N1流感病毒仍将有效,但在开发新疫苗时应该尽可能的避开已经发生漂变的抗原决定簇。

Objective To investigate the variations of the novel influenza A（H1N1） virus neuraminidase in strains isolated from Hangzhou,Zhejiang.Methods Throat swabs from influenza suspect patients were used for viral isolation.Influenza virus subtypes were identified by real-time RT-PCR.The strains of the novel influenza A（H1N1） virus were sequenced and phylogenetically analyzed.Results A total of 720（37.9%） strains of influenza virus were isolated from 1 898 throat swabs between July 2009 and March 2011.The homology of NA amino acid sequences ranged from 97.9% to 100%.The isolated strains of the novel influenza A（H1N1） virus were grouped into two clusters with a significant genetic distance by phylogenetic mapping with other strains.The variations of isolated strains may affect several known epitopes,but none of them was among drug binding sites.The presence of a novel putative glycosylation site was also confirmed at position 42 of the NA stalk.Conclusion The variations of H1N1 influenza NA gene did not affect neuraminidase inhibitors.However,epitope drift should be considered for vaccine development.