湖州市GII.P16-GII.2型诺如病毒胃肠炎疫情的病原分子特征分析

Etiology and Genotype Features Analysis of Acute Gastroenteritis Outbreak Associated with Norovirus GII.P16-GII.2

鉴定湖州市2017年11月3起急性胃肠炎疫情的病原,并对病原进行基因特征研究。收集3起疫情中采集的患者粪便标本,采用荧光定量RT-PCR方法对其进行诺如病毒核酸检测,并对核酸阳性标本进行多聚酶和衣壳蛋白部分区域的RT-PCR扩增。选取阳性扩增产物进行序列测定和分子特征分析。同时收集疫情的相关流行病学资料。3起暴发疫情中15份标本经荧光PCR检测为GII型诺如病毒核酸阳性,其中9份标本成功测序。在线分型、系统进化和重组分析判定3起均是GII.P16-GII.2型重组株引起的诺如病毒感染聚集性疫情。系统进化分析显示,本研究中检出的GII.P16-GII.2与2016年底中国各地以及德国、法国检出的GII.P16-GII.2相聚在一起并区别于2016年以前的GII.P16-GII.2形成了一个相对独立的进化分支。提示2016年新出现的GII.P16-GII.2在多聚酶区和衣壳蛋白区都各自经历了一定进化获得了在人群中广泛流行的能力,具体机制有待进一步的研究。这也是首次在本地的诺如病毒胃肠炎疫情中检出GII.P16-GII.2重组株。

In November 2017,three outbreaks of acute gastroenteritis occurred in three schools in Huzhou City,China.We investigated whether the outbreaks were associated with norovirus.Stool samples collected from 3 outbreaks were analyzed.Samples were tested for norovirus by real-time reverse transcriptionpolymerase chain reaction（RT-PCR）.Partial sequences of RNA-dependent RNA polymerase（RdRp）and capsid genes of the positive samples were amplified by RT-PCR.The PCR products were sequenced and used for phylogenetic analyses.A total of 15 specimens collected from the 3 outbreaks were positive for GII norovirus.On-line classification,phylogenetic analyses and recombination analyses identified that the pathogen to be GII.P16-GII.2 norovirus.Phylogenetic analyses showed that the GII.P16-GII.2 detected in our study was clustered with the GII.P16-GII.2 norovirus detected at the end of 2016 in China,Germany and France,and formed a relatively independent evolutionary branch.The pre-GII.P16-GII.2 norovirus belonged to different evolutionary branches in RdRp and capsid regions.We suggest that the newly emerging GII.P16-GII.2 in 2016 had undergone evolution in polymerase and the capsid regions,and was prevalent in the population.The specific mechanism remains to be further studied.This is the first time that a GII.P16-GII.2 recombinant strain has been detected in norovirus gastroenteritis outbreak in Huzhou.