北京市朝阳区2013-2016年麻疹病毒血凝素基因特征分析

Genetic characterization of hemagglutinin genes of measles virus isolates in Chaoyang district of Beijing, 2013-2016

目的分析2013-2016年北京市朝阳区麻疹病毒分离株的血凝素(H)基因特征。方法对2013-2016年分离获得的H1基因型麻疹病毒进行核酸提取,采用逆转录-聚合酶链反应(RT-PCR)扩增H基因,对扩增产物进行测序,并与中国S191疫苗株、China93-2/H1a参考株序列进行比对分析。结果 2013-2016年分离获得49株H1基因型麻疹病毒。麻疹病毒H基因核苷酸同源性与氨基酸同源性在分离株之间分别为97.7%-100%和98.0%-100%;在分离株与S191疫苗株之间分别为94.0%-94.6%和94.4%-95.3%。49株分离株H蛋白的SLAM、Nectin4受体结合位点的氨基酸无变异;CD46受体结合位点发生481Tyr→Asn变异;7个半胱氨酸残基高度稳定;B细胞抗原决定簇发生240Ser→Asn和243Arg→Gly变异; 240Ser→Asn变异使第五个糖基化位点缺失。12株麻疹病毒分离株形成独立分支,与其余37株分离株相比其H蛋白存在6个氨基酸变异。结论北京市朝阳区H1基因型麻疹病毒H基因比较稳定,麻疹病毒分离株形成两个循环分支,且其中一个分支存在一定变异,需进一步加强麻疹病原学监测研究。

Objective To analyze genetic characterization of hemagglutinin (H)genes of measles virus .circulating in Chaoyang district of Beijing during 2013-2016.Methods We extracted RNAs of H1 genotype measles viruses,amplified the H genes by reverse transcription-polymerase chain reaction (RT-PCR),and sequenced the amplification products.We conducted a sequence,analysis comparing isolated strains with the Chinese S191 vaccine strain and the China93-2/H1a reference strain.Results We obtained 49 strains of H1 genotype measles virus during 2013-2016.The nucleotide and amino acid homologies of H genes within isolated strains were 97.7%-100% and 98.0%-100%,respectively;and between the isolated strains and the S191 strain were 94.0%-94.6% and 94.4%-95.3%.In 49 isolated measles virus strains, no variations were seen at putative binding sites for SLAM and Nectin4 of H proteins;Tyr481 Asn variation was seen at the putative binding site for CD46;seven cysteine residues were highly stable;Ser240Asn and Arg243Gly variations occurred in B cell epitopes ;and Ser240 Asn variation caused absence of the fifth glycosylation site.Twelve isolated measles virus strains formed a single cluster in the phylogenetic tree,with a variation of 6H protein amino acids,compared with 37 other isolated strains.Conclusions H genes of the H1 genotype measles viruses in Chaoyang were stable;isolated strains formed two circulating clusters with a small variation in one.We should strengthen pathogenic studies of measles.