2020~2021年广州市售牡蛎中GII型诺如病毒污染情况调查

Survey of Norovirus Genogroup II Contamination in Commercial Oysters in Guangzhou from 2020 to 2021

滤食性牡蛎是食源性诺如病毒传播的重要食品媒介。为了解广州市售牡蛎中的诺如病毒污染水平与遗传多样性特点,合理评估消费风险,本研究于2020年6月至2021年5月期间,每月从当地水产市场随机采集牡蛎样本,采用实验室前期建立的蛋白酶K处理偶联聚乙二醇沉淀小体系法,包括荧光定量RT-PCR和巢式RT-PCR技术检测贝类中病毒的污染量以及基因型分布特点。结果共检测牡蛎110只,GII型诺如病毒阳性检出率为52.7%(58/110),病毒污染含量范围为1.56×10^(3)~1.09×10^(6) copies/g(消化腺)。其中,春夏季节(3~8月)牡蛎中诺如病毒的阳性率为35.7%(20/56),低于在秋冬季节(9~2月)的阳性率70.4%(38/54);但不同季节中检出的病毒含量无显著差异,分别为春季(2.69±1.46)×10^(5) copies/g(消化腺),夏季(1.97±2.16)×10^(5) copies/g(消化腺),秋季(6.91±6.16)×10^(4) copies/g(消化腺),冬季为(4.83±2.99)×10^(4) copies/g(消化腺)。部分阳性样本测序分析后显示,除1份为GII.17基因型外,其余均为GII.4基因型(n=13),与当地的临床流行基因型呈现一致性。本研究显示广州市售牡蛎中仍存在较高的诺如病毒污染水平,需要进一步加强病毒防控工作,尤其提醒消费者在食用牡蛎时需加工充分。

Filter-feeding oyster is an important food transmission vector for the foodborne norovirus.To investigate the contamination level and genetic diversity of norovirus in commercial oysters in Guangzhou and better assess the risk of consumption,oyster samples were collected from local aquatic market from June 2020 to May 2021 in this study.The contamination content and genotype distribution of virus in shellfish were detected by protease K treatment coupled with polyethylene glycol precipitation small system previously established in the laboratory,including the real-time reverse transcription polymerase chain reaction and the nested RT-PCR.110 oyster samples were detected,the positive rate of norovirus genogroup II(GII)was 52.7%(58/110),and the contents of virus was 1.56×10^(3)~1.09×10^(6) copies/g(digestive gland).The positive rate of norovirus in oysters collected in spring and summer(March to August)was 35.7%(20/56),which was lower than the positive rate of 70.4%(38/54)in autumn and winter(September to February).However,there was no significant difference in content of virus detected in all seasons,in spring,content of virus was(2.69±1.46)×10^(5) copies/g(digestive gland),in summer,content of virus was(1.97±2.16)×10^(5) copies/g(digestive gland),in autumn,content of virus was(6.91±6.16)×10^(4) copies/g(digestive gland),and winter was(4.83±2.99)×10^(4) copies/g(digestive gland).Positive samples were sequenced and analyzed,the result showed that except for one was GII.17 genotype,the rest were all GII.4 genotypes(n=13),which was consistent with the local clinical epidemic genotypes.The results of this study showed that the level of norovirus contamination in commercial oysters of Guangzhou was severe,it is necessary to strengthen control work of prevention for virus,especially to remind consumers to fully process when eating oysters.