珠海市2011—2016年诺如病毒胃肠炎暴发疫情的分子流行病学研究

Molecular epidemiologic study on norovirus gastroenteritis outbreaks in Zhuhai from 2011 to 2016

目的了解珠海市2011—2016年间导致胃肠炎暴发疫情的诺如病毒病原学特征。方法收集2011—2016年间珠海市56起诺如病毒感染导致的胃肠炎暴发疫情病例肛拭子标本576份，应用实时荧光定量RT-PCR技术，检测诺如病毒GⅠ群、GⅡ群核酸，在每起疫情中随机选取3～4份诺如病毒阳性标本，应用RT-PCR技术扩增主要衣壳蛋白VP1区基因片段并测序分型，每起疫情选取1株进行种系进化分析。结果56起胃肠炎疫情中，出现8个基因型，都是GⅡ群。GⅡ.4/2006b于2011—2012年流行季流行后，被其变异株GⅡ.4/Sydney_2012取代，该变异株主导2012—2013流行季，于2013年2月GⅡ.4及其变异株均消失。2014—2015流行季所发生的12起都是GⅡ.17；2015_2016流行季共发生7起都是GⅡ.3；2016年6月到9月分别是GⅡ.17和GⅡ.3；2016年11月—12月12起全部是GⅡ.p16-GⅡ.2。2011—2016年间未发现由GⅠ群病毒引发的疫情。结论引起本地暴发疫情的诺如病毒均为GⅡ群，多个基因型别更替流行。2016年底重组株GⅡ.p16-GⅡ.2出现并引起多起疫情，提示今后监测中应密切关注该重组诺如病毒的流行和进化。

ObjectiveTo describe the molecular epidemiological characteristics of norovirus gastroenteritis outbreaks in Zhuhai from 2011 to 2016.MethodsAnal swab specimens were collected from 576 cases with 56 outbreaks of acute norovirus gastroenteritis from 2011 to 2016. Specimens were tested by real-time RT-PCR. Three to four of norovirus positive specimens were selected from every outbreak to amplify the VP1 gene by RT-PCR and one strain was chosen randomly from every outbreaks to determine the genotype by phylogenetic tree analysis.ResultsEight genotypes were identified from 56 outbreaks and all of them belonged to GⅡ genogroup. The genotype of norovirus strain changed with prevalence time. The GⅡ.4/2006b was dominant from 2011 to 2012, and replaced by GⅡ.4/Sydney _2012 during the 2012—2013 norovirus season, and both of them never appeared after Feb. 2013. GⅡ.17 was the only genotype during the 2014—2015 norovirus season. All the 7 outbreaks occurred from 2015 to 2016 were caused by GⅡ.3 norovirus. The GⅡ.17and GⅡ.3 were identified from Apr. to Sep. 2016; GⅡ.p16-GⅡ.2 were the only genotype in 12 outbreaks from Nov. to Dec. 2016. The GⅠ genogrope was never identified from 2011 to 2016 in Zhuhai.ConclusionsThe Norovirus GⅡ was the only pathogeny which caused the outbreaks of norovirus gastroenteritis. The recombinant norovirus strain GⅡ.p16-GⅡ.2 emerged and caused large outbreaks in the last two months of 2016 in Zhuhai; several recombinant strains of the GⅡ.p16 RdRp gene were found now, which suggests that attention should be focused on the prevalence and evolution of the recombinant norovirus.