2017-2018年湖州市柯萨奇病毒A6型流行情况及VP1区基因特征分析

Epidemiological characteristics of Coxsackie virus A6 and virus VP1 genetic features in Huzhou in 2017-2018

目的了解2017-2018年湖州市手足口病疑似病例中的柯萨奇病毒A组6型(coxackievirus A6,CVA6)的流行情况及基因特征。方法 2017-2018年收集774份手足口病疑似病例样本,采用荧光定量RT-PCR方法进行肠道病毒核酸检测,并对检出的CVA6进行VP1全长基因序列的扩增和序列测定,利用Mega 5.2进行序列分析并构建系统进化树。结果肠道病毒阳性样本601份,总阳性率为77.65%(601/774)。其中2017年度的优势病原为CVA16占36.33%(89/245),2018年的优势病原为CVA6占36.52%(130/356)。CVA6阳性病例中,男女性别比为1.77∶1,3~<4岁组病例占比最高(83.87%)。系统进化分析显示2017-2018年检出的CVA6聚为一个分支,属于D3a基因亚型,与同属于一个分支上的2014年CVA6江西分离株亲缘关系较近。结论 CVA6是湖州市2018年引起手足口病的主要病原,CVA6湖州株仍属于D3a基因亚型。应持续开展CVA6分子流行病学监测,对疫苗的研发和手足口病的预防控制具有重要意义。

Objective To understand the epidemiological and genetic characteristics of Coxackie virus A6(CVA6) associated with hand, foot and mouth disease(HFMD) in Huzhou from 2017 to 2018. Methods A total of 774 clinical samples were collected from patients with suspected HFMD from 2017 to 2018.The viral RNA was extracted and subjected to enterovirus nucleic acid detection by real-time RT-PCR.Full-length VP1 gene of CVA6 in positive samples were sequenced and phylogenetic tree was constructed using Mega 5.2. Results 601 samples were Enterovirus positive with the positive rate of 77.65%(601/774).The predominant enterovirus pathogen was CVA16(36.33%) in 2017 and was CVA6(36.52%) in 2018.Among cases with CVA6 positive, the male to female ratio was 1.77∶1, and most cases were in 3~<4 years old age group.Phylogenetic analysis showed that CVA6 strains identified in Huzhou in 2017 and 2018 clustered into D3 a gene subtype branch and were closely related to the CVA6 strains isolated from Jiangxi in 2014. Conclusions CVA6 is the major enterovirus pathogen causing HFMD in Huzhou in 2018, which belongs to the D3 a gene subtype.The epidemiological surveillance of CVA6 is of great significance for the development of vaccines and the prevention and control of HFMD.