2013年南京市甲型H1N1流感病毒NA基因的进化分析

目的 :调查2013年南京地区新型甲型H1N1流感病毒神经氨酸酶(NA)基因的分子特征,了解NA基因的变异情况,分析NA基因进化特征。方法:提取18株新型H1N1流感病毒基因组RNA,RT-PCR扩增NA基因,测序并分析其遗传进化特征和重要功能位点。结果:2013年南京分离株与国内外推荐疫苗株NA基因高度同源,序列相似性达98.2%以上。18株分离株在进化树上分为2支,与国内疫苗株接近,与国际疫苗株存在一定的遗传距离;与国内外疫苗株相比,多个位点氨基酸发生变异;1株分离株的酶活性位点119位发生了变异;部分分离株糖基化位点也出现了增加和缺失的现象。结论:南京市2013年流行株与国内外疫苗株NA基因同源性仍然较高,疫苗依然有效。2013年后期的甲型H1N1流感病毒神经氨酸酶基因累积了更多的变异,需加强监测。

Evolution analysis of NA genes of influenza A( H1N1) virus in Nanjing in 2013

Objective:To stady the genetic variations and evolution characteristics of neuraminidase (NA) gene of the novel influenza A(H1N1) virus isolated from Nanjing in 2013. Methods:Viral RNA was extracted from 18 strains of the novel influenza A (H1N1) virus. NA genes were amplified by RT-PCR and then sequenced. The genetic variations and important functional sites of NA genes were analyzed. Results:Compared with recommended vaccine strain in and abroad, the homology of NA amino acid sequences between 18 Nanjing isolates and vaccine strains was above 98.2%. The isolats were grouped into two clusters, with some genetic distance by phylogenetic mapping with the WHO vaccine stain,while closer to the domestic vaccine stain. Compared to the vaccine strains,the variations of amino acids occurred in different sites;1 isolate had a E119K replacement in enzymatically active site;Glycosylation sites appeared to be increased or deleted in the 2013 isolats. Conclusion:High homology was observed in all the NA genes between the strains isolated from Nanjing in 2013 and vaccine strains. The vaccine can continue provide a protection. However,more mutations were accumulated in NA genes in the strains isolated in the late of 2013. Therefore,the monitoring should be strengthened.