安徽省急性胃肠炎疫情相关GⅡ.P17-GⅡ.17基因型诺如病毒分子特征研究

Molecular Characterization of GⅡ.P17-GⅡ.17 Norovirus Associated with Acute Gastroenteritis Outbreaks in Anhui Province,China

诺如病毒(Noroviruses,NoVs)是引起病毒性胃肠炎的重要病原体,本研究旨在对2015～2016年春季安徽部分地区暴发的急性胃肠炎(Acute gastroenteritis,AGE)疫情标本进行病原检测和分子分型,分析病原的基因特征。收集2015年3月至2016年5月9起AGE疫情流行病学信息和采集病例粪便、肛拭子样本。采用Real-time PCR检测NoVs核酸和RT-PCR扩增RdRp与VP1区基因序列,基因测序后应用BLAST比对和NoVs在线分型工具分析结果。7起疫情发生在中、小学校(77.78%,7/9),2起疫情发生在乡镇,发病人数中位数为6人,男女发病比例为1.41∶1,临床表现主要以恶心、呕吐/腹泻、腹痛为主。77份临床病例样本中检出66份NoVs核酸阳性,基因序列测定获得76条序列,39条序列为RdRp区GⅡ.P17基因型,37条序列为VP1区GⅡ.17基因型。基因进化树分析显示:2015～2016年安徽地区39条RdRp区NoVs GⅡ.P17基因型序列Cluster III进化簇III b分支,与2015年广东、海南、中国台湾地区参考毒株序列有较近的亲缘性关系,核苷酸同源性为99%～100%。37条VP1区NoVs GⅡ.17基因型序列都处在Cluster III进化簇上,其中28条序列属于III a进化分支,与山东2015年LX09株、2016年广东GZ2016-L492株、江苏zj019株、中国香港CUHK-NS-942株以及日本2015年AichiF101毒株序列有较近的亲缘性关系。新型GⅡ.P17-GⅡ.17基因型NoVs是引起2015年和2016年春季安徽部分地区AGE暴发的主要病原体,需加强病毒性胃肠炎流行病学调查与病原监测及分子分型鉴定工作。

To study the genotype and phylogeny of the pathogens related to the epidemic outbreaks of acute gastroenteritis(AGE)in Anhui Province,China,during March 2015 to May 2016,epidemiological data of nine AGE outbreaks and anal swab or fecal samples from the patients were collected.Noroviruses(NoVs)nucleic acids in the samples were tested by real - time PCR,and partial genes of the NoVs RdRp and VP1 regions were amplified by conventional RT -PCR.Genotypes of the sequences were assigned by using BLAST and NoVs genotyping tool(http://www.rivm.nl/mpf/norovirus/ typingtool).Seven outbreaks occurred in primary and secondary schools(77.78%,7 / 9);two outbreaks occurred in villages and towns.The median number of cases was six,and the male to female incidence ratio was 1.41∶1.The main clinical manifestations of patients were nausea,vomiting,diarrhea and abdominal pain.Sixty - six NoVs nucleic acid - positive samples were detected from seventy -seven clinical cases.Seventy -six sequences were obtained successfully,thirty -nine of which were RdRp GII.P17 genotype and thirty - seven of which were VP1 GII.17 genotype.Phylogenetic analysis showed that thirty -nine RdRp NoVs GII.P17 genotype sequences belonged to evolutionary cluster Ⅲb and were closely related to reference strain sequences from Guangdong,Hainan and Taiwan of China in 2015(nucleotide homology 99%~100%).Thirty-seven NoVs GII.17 VP1 sequences belonged to evolutionary cluster Ⅲ,twenty-eight of which belonged cluster Ⅲa.They were closely related to strain LX09 from Shandong Province,China in 2015,strain GZ2016 - L492 from Guangdong Province in 2016,strain zj019 from Jiangsu Province,China, strain CUHK -NS -942 from Hong Kong,China and strain AichiF101 from Japan in 2015.Norovirus genotype GII.P17-GII.17 was the predominant pathogen causing AGE outbreaks in Anhui Province during 2015~2016.It is necessary to strengthen epidemiological investigation,pathogen monitoring and molecular typing for viral gastroenteritis.