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目的分析南宁市2013-2014年A(H3N2)亚型流感病毒的病原学特征及流行趋势。方法通过RT-PCR扩增毒株A(H3N2)病毒血凝素(HA)基因和神经氨酸酶(NA)并进行同源比对,采用Mega5.1(N-J法)构建系统进化树,统计氨基酸位点的差异,同源建模后分析蛋白结构的变化。结果构建系统进化树,20株毒株HA基因与NA基因均分为4个类群,呈多侧支流行;部分毒株的HA蛋白A抗原决定簇144位点及B抗原决定簇156和158位点发生突变,二硫键和糖基化位点高度保守,未发生变化;NA蛋白抗原基本稳定,只有A/Nanning/43/2014(H3N2)毒株抗原决定簇312位点发生突变,二硫键、酶活性位点、糖基化位点及耐药性位点均未发生变化;HA和NA蛋白晶体结构分析显示氨基酸突变位点主要发生在β折叠部位和无规则卷曲处。结论南宁市A(H3N2)亚型流感病毒株变异活跃,在HA基因和NA基因进化树上疫苗株明显滞后于南宁市流行株,抗原决定簇位点出现氨基酸的替换,但关于疫苗的预防效果尚需进一步验证。
Objective To analyze the etiological characteristics and epidemiological trends of influenza A (H3N2) virus from 2013 to 2014 in Nanning. Methods The hemagglutinin (HA) gene and neuraminidase (NA) of strain A (H3N2) were amplified by RT-PCR and homologized. The phylogenetic tree was constructed by using Mega5.1 (NJ method) Amino acid site differences, analysis of protein structure changes after homology modeling. Results The phylogenetic tree was constructed. The HA gene and NA gene of 20 strains were divided into 4 groups, showing multi-lateral branch epidemiology. Some of the 144 strains of HA protein A epitopes and 156 and 158 of B antigenic determinants Point mutations occurred. The disulfide bonds and glycosylation sites were highly conserved and did not change. The NA protein antigen was basically stable. Only the 312 site of the A / Nanning / 43/2014 (H3N2) strain was mutated. Key, enzyme active site, glycosylation site and drug-resistant sites did not change; HA and NA protein crystal structure analysis showed that amino acid mutation sites occur mainly in the β-fold and irregular curl. Conclusions The influenza A (H3N2) subtype influenza virus strain in Nanning City is highly variable. The vaccine strains in the HA gene and NA gene phylogenetic tree obviously lag behind the epidemic strains in Nanning City, and amino acid substitution occurs at the antigenic determinant site. However, the preventive effect of the vaccine Still need further verification.