引起一起暴发性急性胃肠炎疫情的埃可病毒18型VP1基因特征分析

埃可病毒18型(Echovirus 18,E18)属于B组肠道病毒(Enterovirus B,EV-B),是引起病毒性脑膜炎的重要病原体。对2019年4月广东省深圳市龙岗区一起急性胃肠炎疫情进行病原学鉴定及病原基因特征分析。此次疫情共有26名患者,均以发热、呕吐、腹泻、腹痛为主要症状。从其中18名病例采集了18份肛拭子标本,采用实时荧光RT-PCR、病毒分离(RD细胞)和半巢式聚合酶链反应法以鉴定病原,扩增病毒全长VP1区,测序并进行系统进化分析。结果显示,18份标本中11份肠道病毒核酸阳性,其中8份为E18。病毒分离得到2株病毒,从肛拭子标本直接扩增得到的7条E18全长VP1核苷酸序列,核苷酸相似性为100%,与GenBank中E18参考株的核苷酸及氨基酸同源性分别为79.2%~96.4%和93.3%~99.3%;进化树显示,深圳龙岗E18分离株(GDSZ1902)归属由中国分离株组成的C2a进化分支,在其VP1蛋白中的底部环处发现一处特异的氨基酸变异(D200N)。从流行病学和病原学结果分析,E18是引起本次深圳市龙岗区急性胃肠炎疫情的主要病原,属于中国E18主要流行株的进化分支,这是我国首次发现E18引起急性胃肠炎疫情的报道。

Genetic Characteristics Analysis of VP1 Sequence of Echovirus 18 that Caused an Acute Gastroenteritis Outbreak in Guangdong Province,China

Echovirus 18(E18),a serotype of Enterovirus B(EV-B)species,is an important pathogen in aseptic meningitis.To identify and analyze the pathogen genetic characteristics of the pathogens that caused an acute gastroenteritis outbreak in Longgang District of Shenzhen(Guangdong Province,China)during April2019,26 patients were collected in the epidemic,all with fever,vomiting,diarrhea,and abdominal pain as main symptoms.Pathogens were identified from anal swab samples with real time fluorescent PCR,virus isolation(RD cells),and semi-nested PCR(Sn-PCR).The whole genome nucleotide sequences of VP1 were amplify by RT-PCR and sequenced.Phylogenetic analysis was performed.Finally,of 18 samples from patients,11 were detected positive for enteroviruses RNA.Among them,8 samples were identified as E18 using enterovirus molecular typing,including two live viruses.The whole genome nucleotide sequences of VP1 were successfully amplified from 7 E18 strains and sequenced from anal swab specimens,and their nucleotide homology were 100%.The nucleotide and amino acid sequence identity between the E18 strain(GDSZ1902)in this study and representative E18 strains from GenBank database were 79.2%-96.4%and 93.3%-99.3%,respectively.Phylogenetic analysis of VP1 gene sequences revealed that the E18 strain(GDSZ1902)from this study belongs to sub-genotype C2 a,which were composed primarily of E18 strains from China.A D200 N amino acid change in the bottom loop structure of the VP1 protein was detected in the E18 strain(GDSZ1902).According to the analysis of epidemiological and etiological results,E18 was the main pathogen that caused acute gastroenteritis outbreak in Longgang District,Shenzhen City,China,in 2019.The E18 isolate(GDSZ1902)causing this outbreak aggregated into the sub-genotype C2 a,which was derived from E18 strains that circulated in China in recently years.This is the first report that E18 caused acute gastroenteritis in China.