为了解引起2017年10月甘肃省兰州市一起疱疹性咽峡炎(Herpangina,HA)暴发疫情的致病病原体及其病原学特征,对采集的患儿的37份咽拭子样本开展病毒分离培养,然后对分离到的毒株采取一代测序获取VP1区全长核苷酸序列,根据分子定型的方法进行肠道病毒型别鉴定.根据VP1区核苷酸差异选择3个毒株进行二代测序,获取全基因组序列.使用MEGA软件(版本号11.0)进行病毒的核苷酸,氨基酸相似性分析,VP1区的氨基酸突变位点分析,并构建系统发育树,使用Simplot(版本号3.5.1)软件进行病毒重组分析.本次疫情中分离到的毒株鉴定为柯萨奇病毒A2型(Coxsackievirus A 2,CV-A2),分子分型显示属于D基因型,且VP1区第102位氨基酸发生了丙氨酸到甘氨酸(A102G)的突变,与省内2014-2015年分离到的两株CV-A2毒株在该位置的突变不同.重组分析发现,病毒在P2区和P3区发生了以CV-A4为主的重组事件.本次疫情的致病病原体CV-A2存在着VP1区氨基酸A102G的特征性变异及P2区和P3区的重组,需要加强对肠道病毒的变异和重组的监测和研究,以提升预警能力.
Analysis of the Genetic Characteristics of CV-A2 that Caused A Herpangina Outbreak in Lanzhou,China in 2017
In order to understand the pathogen and its pathogenic characteristics that caused an outbreak of herpangina(HA)in Lanzhou City(Gansu Province,China)in October 2017.Viral isolation was carried out on 37 throat-swab samples collected from pediatric patients.Then,the full-length nucleotide sequence of the VP1 region was obtained by Sanger sequencing of viral isolates.The enterovirus type was identified using molecular stereotyping method.Three strains were selected based on nucleotide differences in the VP1 region for next-generation sequencing to obtain the entire genome sequence.Nucleotides and amino acid similarity analysis of the virus,amino acid substitutions analysis in the VP1 region of the virus,and phylogenetic trees were conducted using MEGA(version 11.0),recombination analysis was performed using Simplot software(version 3.5.1).The virus isolated in this outbreak was identified as Coxsackievirus A2(CV-A2),and molecular typing showed that it belongs to the D genotype.The amino acid site 102 in the VP1 region underwent a mutation from alanine to glycine(A102G),which is different from the two CV-A2 strains isolated in Gansu Province from 2014 to 2015.Recombination analysis revealed that the virus underwent recombination events with Coxsackievirus A4(CV-A4)in the P2 and P3 regions.The pathogen of this outbreak,CV-A2,had characteristic mutations of A102G in the VP1 region and recombination in P2 and P3 regions.Therefore,it is necessary to strengthen surveillance and research on the mutations and recombination of enteroviruses to enhance early warning capabilities.
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