一株2011年出现的季节性甲型H1N1流行性感冒病毒血凝素基因特性的研究

Analysis of hemagglutinin gene of a seasonal influenza A(H1N1) virus isolated in 2011

本文通过比较2011年分离培养的1株季节性甲型H1N1流行性感冒(简称流感)病毒(A/Shanghai/1167/2011(H1N1))与历年季节性甲型H1N1流感病毒的血凝素(HA)基因,追溯该病毒的基因变异与来源,探讨该毒株的出现对流感防控工作的意义。采用反转录-聚合酶链反应(RT-PCR)方法扩增病毒的HA和神经氨酸酶(NA)片段,并进行测序;应用分子生物学软件对获得的序列进行分析,绘制基因进化树;同时,通过血凝抑制试验检测2011年下半年健康人群中该流感病毒的抗体水平。结果显示,A/Shanghai/1167/2011(H1N1)的HA基因序列与世界卫生组织(WHO)2007～2008年季节性甲型H1N1流感病毒疫苗株A/Brisbane/59/2007(H1N1)最接近,同源性达99.2%,与新型甲型H1N1流感病毒A/California/07/2009疫苗株同源性仅为72.4%。其HA基因裂解位点为PSIQSR↓GLF,尚未出现高致病性的分子特征。HA片段共编码557个氨基酸,有9个潜在的糖基化位点,序列与2009年前WHO疫苗株A/NewCaledonia/20/1999(H1N1)、A/SolomonIslands/3/2006(H1N1)和/Brisbane/59/2007(H1N1)相比,分别有15、12和4处不同,这些差异分布在Sa、Sb、Ca1、Ca2、Cb5个抗原决定簇的氨基酸差异分别有5、5和2处。该毒株在健康人群血清的抗体阳性率为34.33%,几何平均效价(GMT)为10.38。A/Shanghai/1167/2011(H1N1)是2011年出现在上海地区的一个季节性甲型H1N1流感病毒毒株,其抗原变异与既往季节性甲型H1N1流感病毒相比不大,但在以A(H1N1)pdm09为主要流行株的年份检测到散在发生的既往季节性甲型H1N1流感病毒毒株应当引起重视,其在人群中的抗体水平较低,易引起流行,需要提高对类流感人群中此种毒株的持续监测。

The present paper aims to compare the hemagglutinin （HA） gene of a seasonal influenza A（H1N1） virus isolated in 2011 with the gene from reported seasonal influenza A（H1N1） viruses. The HA fragment and full-genome of A/Shanghai/1167/2011 （H1N1） were amplified by reverse transcriptase-polymerase chain reaction （RT-PCR）. Molecular biology software was used to analyze the sequences and draw the phylogenetic tree. The anti-virus antibody level in healthy people was detected by hemagglutination inhibition test. The results showed that the HA gene of A/Shanghai/1167/g011（H1Nl） was similar to the HA genes from previous reported seasonal influenza A（H1N1） viruses, with homology of 99.2% to the 2008-2009 seasonal influenza A（HIN1） vaccine strain A/Brisbane/59/2007（H1N1）, and 72.4% to the A/ California^07~2009 vaccine strain respectively. The HA cleavage site was PSIQSR ~ GLF, and highly pathogenic molecular characteristics had not appeared yet. HA fragment, encoding 557 amino acids, has nine potential glycosylation sites. Its amino acid sequence was compared with the World Health Organization （WHO） vaccine strains of influenza A/NewCaledonia/20/1999（H1N1）, A/SolomonIslands/3/2006（H1N1）, and A/Brisbane/59/2007 （H1N1） respectively. The identified amino acid differences were 15, 12 and 4 respectively, and part of these differences （5/15, 5/12 and 2/5） were located inside the critical epitope clusters （Sa, Sb, Cal, Ca2 and Cb）. Our results indicated that in 2011, 34.33% of healthy people carried antibodies against the isolated strain in their sera, and the geometric mean titer （GMT） was 10.38. A/ Shanghai/l167/2011（HiN1） is a seasonal influenza A（HIN1） strain isolated in Shanghai in 2011. Although no significant differences were identified when comparing it to seasonal influenza A （H1N1） viruses, its detection after A（H1N1）pdm09 was identified as the predominant strain should arouse people＇s attention. Its antibody level in population is low, and can easily cause a pandemic. The monitoring of such strains in influenza-like population should be improved.