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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 understand the variation of neuraminidase gene (NA) of influenza A (H1N1) virus in Hangzhou since July 2009 and analyze its genetic evolution characteristics. Methods The throat swab samples of febrile patients were collected during the epidemic season. After isolation and cultivation of virus and identification of subtypes, NA genes were amplified by specific primers and their genetic evolution characteristics were sequenced and analyzed. Results From July 2009 to March 2011, a total of 1 898 monitoring samples were tested, and the positive rate of influenza virus was 37.9%. During the two influenza H1N1 influenza epidemic peak. The NA genes were highly homologous among isolates at different time points with sequence similarity of 97.9% -100%. However, the epidemic strains were divided into two in evolutionary tree in 2010/2011, and were far away from the genetic distance in 2009/2010 epidemic strains . After further analysis, it was found that although the amino acid residues at the drug resistance site and enzyme sites were relatively conservative, a number of amino acid mutations occurred on the epitopes and increased the 42nd glycosylation site in the stem of NA protein. Conclusions The results indicate that enzyme inhibitor drugs will still be effective in preventing and treating influenza A (H1N1) virus. However, in the development of new vaccines, drift-inhibiting epitopes should be avoided as much as possible.