2019-2022年南京市急性胃肠炎暴发疫情中诺如病毒分子流行病学分析

Molecular Epidemiological Analysis of Norovirus in Acute Gastroenteritis Outbreaks in Nanjing,China,2019-2022

诺如病毒是引起急性胃肠炎的主要病原体之一,本研究通过分析2019-2022年南京市诺如病毒急性胃肠炎暴发的流行特征和主要基因型变化,为疫情防控提供依据。收集2019年9月至2022年8月南京市疑似诺如病毒急性胃肠炎暴发样本,通过荧光定量PCR和一步法RT-PCR检测,对阳性样本进行序列测定并分型,挑选48株南京代表株与国内外参考株进行同源性分析。2019-2022年南京市诺如病毒急性胃肠炎暴发的高峰为冬春季,场所主要分布在小学和幼儿园,暴发以诺如病毒GII为主,共检测到11种基因型,包括4种GI和7种GII。主要流行株在三个流行季间有所变化,GII.2[P16]为2019-2021年的优势流行株,2021/2022流行季中GII.4 Sydney 2012[P16]亚型、GII.17[P17]亚型占比最大,多种亚型毒株共存。同源分析发现,2021年2株GII.6[P7]南京株分属于两类不同来源的GII.6衣壳基因型,2019-2022年的GII.2[P16]和GII.4 Sydney 2012[P16]南京株的部分聚合酶区序列变化较衣壳蛋白区大。2019-2022年间南京市诺如病毒急性胃肠炎暴发数量呈上升趋势,并且主要流行基因型发生改变。

Norovirus(NoV)is one of the main pathogens causing acute gastroenteritis(AGE).In this study,the epidemic characteristics and predominant genotype changes of the NoV in AGE outbreaks in Nanjing,China from 2019 to 2022 were analyzed to provide evidence for epidemic prevention and control.Specimens of suspected AGE outbreaks caused by NoV were sent by 12 district Center for Disease Control and Prevention in Nanjing,China from September 2019 to August 2022.We conducted fluorescence quantitative polymerase chain reaction(PCR)and one-step reverse transcription-PCR(RT-PCR)with the specimens.NoV-positive samples were sequenced and genotyped.48 representative Nanjing,China strains were selected for phylogenetic analysis with domestic and overseas reference strains.A total of 85 AGE outbreaks caused by NoV occurred in Nanjing,Chinafrom 2019 to 2022.NoV outbreaks peaked in winter and spring,and mainly occurred in primary schools and kindergartens.NoV outbreaks in 2019-2022 were mainly caused by NoV GII A total of 11 genotypes were detected,including 4 GI and 7 GII.The predominant epidemic genotypes changed among three epidemic seasons.GII.2[P16]was the predominant genotype from 2019 to 2021.GII.4 Sydney 2012[P16]and GII.17[P17]accounted for the largest proportion in 2021/2022 epidemic season with other multiple genotypes coexisting.Homology analysis showed that two GII.6[P7]Nanjing strains from 2021 belonged to two clusters of GII.6 capsid genotype.Nucleotide changes in partial polymerase region of GII.2[P16]and GII.4 Sydney 2012[P16]Nanjing strains fwere greater than in partial capsid protein region rom 2019 to 2022.Overall,the number of NoV outbreaks showed an increasing trend and the predominant genotypes changed during three epidemic seasons.Therefore,continuous surveillance and in-depth study should be focused on the variation of important genotypes in the future.