2020年昆明市6起手足口病聚集性疫情病原学监测及CV-A6分子特征分析

Analysis of etiological surveillance and genetic characteristics for 6 aggregated epidemics of hand,foot and mouth disease in Kunming,2020

目的了解云南省昆明市手足口病的病原学特征,分析主要病原柯萨奇病毒A6型(Coxsackievirus A6,CV-A6)的流行特征。方法采集昆明市2020年6起手足口病聚集性疫情中19个病例的粪便样本,用实时荧光RT-PCR法检测肠道病毒并测定VP1基因序列,比较核苷酸、氨基酸序列同源性,并进行氨基酸位点变异及基因进化分析。结果19份粪便样本中有18份检出肠道病毒核酸,其中14份为CV-A6阳性,测序成功13份,均为D3基因亚型D3a进化分支。13株CV-A6之间核苷酸同源性为97.2%~100.0%,氨基酸同源性为98.7%~100.0%,12株与2020年曲靖株(LC626198、LC626200)亲缘关系较近,1株与2019年眉山株(MW178716)亲缘关系较近。测序成功的13株CV-A6VP1区氨基酸变异主要在S97N、A128V、E129G、F130S、T131P和S139R等位点,未出现V174I变异。结论2020年昆明市手足口病聚集性疫情的主要病原是CV-A6,属于D3基因亚型D3a进化分支。

Objective To investigate the etiological characteristics of hand,foot and mouth disease(HFMD)in Kunming,Yunnan province,and to analyze the genetic characteristics of the important pathogen Coxsackievirus A6(CV-A6).Methods A total of 19 fecal samples from 19 cases involved 6 aggregated epidemics of HFMD were collected in2020.Enterovirus of the samples was detected by Real-time RT-PCR and the VP1 gene was sequenced,and the similarity of nucleotide and amino acid were analyzed.The amino acid variation and phylogenetic analysis were performed as well.Results Enterovirus was detected positive in 18 of 19 fecal samples,of which 14 were CV-A6positive and 13 were sequenced successfully,all belonging to the evolutionary branch of D3a gene subtype D3.The similarities of nucleotide and amino acid of 13 CV-A16 strains were 97.2%-100.0%and 98.7%-100.0%respectively.Twelve strains were closely related to the 2020 Qujing strains(LC626198,LC626200),and 1 strain was closely related to the 2019 Meishan strain(MW178716).The main amino acid variation in VP1 region of CV-A6strains was S97N,A128V,E129G,F130S,T131P and S139R,but no V174I variation was found.Conclusion CV-A6which belongs to the evolutionary branch of D3a gene subtype D3,was the main pathogen of the cluster epidemic of hand,foot and mouth disease in Kunming,2020.