肠道病毒71型B5基因亚型全基因组序列分析

Whole genomic sequence analysis of human enterovirus A71 subgenotype B5

目的对北京市一起手足口病聚集疫情进行病原学鉴定,明确其来源及基因组进化特征.方法收集7份患者咽拭子样本,用荧光定量RT-PCR方法鉴定病原血清型.用RT-PCR扩增VP1片段并构建进化树,用于判断基因分型.RT-PCR扩增全基因组序列,计算各基因片段与参考株相似性,分析其基因重组及分子进化特征.结果该起手足口病聚集疫情由B5亚型人肠道病毒A组71型(human enterovirus 71,EV-A71)引起.全基因组序列比对结果显示,各段基因均与B5亚型EV-A71参考株具有最高的相似性.基因重组分析结果表明,B5亚型EV-A71在进化过程中不断与A组肠道病毒在5'UTR区、P2区和P3区发生基因重组.结论应密切监测输入性手足口病病例,关注EV-A71基因变异特征,评估现有疫苗对输入病毒的保护效力.

Objective To identify the causative agent of a hand,foot,and mouth disease(HFMD)outbreak and to elucidate the source and the genomic evolutionary characteristics.Methods Throat swab samples were collected from seven patients.Real-time RT-PCR was used to identify serotypes of the pathogens.Full-length VP1 gene was obtained to construct a phylogenetic tree to determine the genotypes.Whole genome sequences were amplified by RT-PCR and the similarities between each gene fragment and the reference strains were calculated to analyze the characteristics of genetic recombination and molecular evolution.Results The HFMD outbreak was caused by the human enterovirus A71(EV-A71)subgenotype B5 strain.Alignment results of genome sequences showed that every gene fragment had the highest similarity with the reference strain of EV-A71 subgenotype B5.Gene recombination analysis showed that the strains of EV-A71 subgenotype B5 were genetically recombined with the group A enterovirus in the 5'UTR region,P2 region and P3 region during the evolution process.Conclusions The imported HFMD cases and genetic evolution of the causative agents should be closely monitored.The efficacy of existing vaccines against EV-A71 for newly imported virus strains should be assessed.