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目的对2007～2009年度南宁市流行性感冒的病原学监测结果进行分析,了解南宁市H3N2亚型人流感病HA1基因变异规律和进化趋势。方法随机选择2007～2009年流感病原学监测中分离到的H3N2亚型毒株30株(每年10株),提取病毒RNA,采用RT-PCR扩增病毒HA基因后进行核苷酸序列测定,利用VectorNTI9.0对测序结果进行分析处理,并与WHO推荐疫苗株进行比对,用Mage4.1构建系统进化树。结果 HA1氨基酸序列的系统进化树表明,南宁市2007～2009年H3N2亚型人流感病毒株被分为4个分枝,大多数2007、2008年毒株与疫苗株交叉分布于分支Ⅰ和Ⅱ,2009年毒株独立形成一个分支Ⅳ。2007年388、390、406毒株HA1发生了一个氨基酸的插入,其他毒株序列则比较保守。与疫苗株相比,2007～2009年毒株HA1二硫键和受体结合位点(RBS)位点高度保守,而糖基化位点、抗原决定簇位点均发生了不同程度的变异。结论南宁市2007年与2008年H3N2流感病毒HA1基因特性与疫苗株接近,2009年毒株发生了较大变异。WHO推荐的当年疫苗株均滞后南宁流行株。
Objective To analyze the epidemiological surveillance results of influenza in Nanning City from 2007 to 2009 to find out the variation regularity and evolutionary trend of HA1 gene of human influenza type H3N2 in Nanning City. Methods Thirty strains of H3N2 subtypes (10 strains per year) were isolated from influenza aetiology in 2007-2009 randomly. The viral RNA was extracted and the nucleotide sequence of the virus was determined by RT-PCR. VectorNTI9.0 sequencing results were analyzed and compared with the WHO recommended vaccine strains were constructed using Mage4.1 phylogenetic tree. Results The phylogenetic tree of the amino acid sequence of HA1 showed that H3N2 subtype influenza virus strains from 2007 to 2009 in Nanning were divided into four branches. Most of the strains were crossed with vaccine strains in branches Ⅰ and Ⅱ in 2007 and 2008, In 2009, the strain formed a branch IV independently. In 2007 388,390,406 strain HA1 an amino acid insertion occurred, the other strain sequences are more conservative. Compared with the vaccine strain, the HA1 disulfide bond and the receptor binding site (RBS) were highly conserved between 2007 and 2009, while the glycosylation sites and antigenic determinants varied in varying degrees. Conclusion The HA1 gene of H3N2 influenza virus in Nanning City in 2007 and 2008 was similar to that of the vaccine strain, and the strain of 2009 had a large variation. The vaccine strains recommended by WHO lagged the epidemic strains of Nanning at that time.