H3N2亚型流感病毒分离株全基因组序列特征分析及其临床意义

Analysis of characteristics of complete genomic sequence of isolated strains of influenza virus H3N2 and clinical significance

目的分析H3N2亚型流感病毒流行株的全基因组序列及其与临床特征的相关性。方法检测2014年12月—2015年3月收集的呼吸道感染患者鼻拭子样本,对其中H3N2亚型流感病毒株PCR扩增后直接进行全基因组测序,分析其核酸序列特征及氨基酸变异情况。结果与WHO推荐2014—2015流感疫苗株参考病毒株相比,来自不同患者的14个病毒株HA1蛋白抗原决定簇均发生不同程度突变,抗原决定簇结构改变较明显的病毒株其宿主具有更高的体温和更严重的临床表现。全部14个病毒株发生HA1蛋白E190D氨基酸突变。6个病毒株NA蛋白出现1个新增糖基化位点。1个病毒株存在导致金刚烷胺耐药的M2蛋白V27A突变。全部14个病毒株PB1-F2蛋白发生I18T突变。结论 M2蛋白耐药突变的出现和PB1-F2蛋白氨基酸突变提示分离获得的H3N2流感病毒株在进化过程中曾经结合H1N1亚型流感病毒基因片段。HA1蛋白抗原决定簇突变的增加可能引发患者更强的免疫反应。

Objective To analyze the correlation between the complete genomic sequence of prevalent strains of influenza virus H3N2 and clinical characteristics. Methods Nasal swab samples of patients with respiratory tract infection collected from December 2014 to March 2015 were used to perform the complete genomic sequencing for strains of influenza virus H3N2 after PCR amplification. Characteristics of nucleic acid sequence and amino acid variations were analyzed. Results Compared with reference strains of 2014 -9015 influenza virus strains recommended by WHO, the epitope of HA1 protein of 14 strains from different patients varied. For hosts with significant structural changes of epitope, their body temperature was higher and clinical manifestations were severer. The amino acid E190D of HA1 protein of all 14 strains varied. A new glycosylation site appeared in NA protein of 6 strains. One strain has the V27A variation of M2 protein that caused the amantadine resistance. All 14 strains had the llST variation of PB1-F2 protein. Conclusion Drug resistance variation of M2 protein and amino acid variation of PB1-F2 protein suggest that isolated strains of influenza virus H3N2 have combined with gene fragments of influenza virus H1N1 during the course of evolution. The increase of variations of the epitope of HA1 protein may cause stronger immune response of patients.