GII.P7/GII.14型诺如病毒暴发的分子特征分析

摘要

目的 了解江苏地区3起诺如病毒(Norovirus,NoV)暴发疫情中病毒感染情况,并对其分子流行病学特征进行初步研究.方法 收集暴发疫情中患者的肛拭子标本53份,采用实时荧光RT-PCR定性检测NoV,阳性标本利用普通RT-PCR对其聚合酶区(RNA-dependent RNA polymerase,RdRp)及衣壳蛋白区(VP1)片段进行扩增和测序分析.结果 3起NoV暴发疫情中,阳性检出率为56.6%(30/53).对30株阳性标本序列进行分析,其RdRp区与GII.P7的同源性最高(93.86%),VP1区与GII.14的同源性较高(97.13%).初步判断为GII.P7/GII.14重组毒株,SimPlot分析可能的重组位点在核苷酸5009位.对其氨基酸序列进行分析发现在RdRp区和VP1区均出现部分氨基酸突变.结论 3起NoV暴发疫情均由同一重组毒株引起,提示GII.P7/GII.14重组株传染性较强,有可能再次引起暴发,应加强监测防控.%Objective To study the infection status and molecular epidemiological characteristics of three outbreaks caused by norovirus (NoV). Methods A total of 53 fecal specimens were collected from the patients during the outbreaks. Real-time RT-PCR was used as a qualitative detection of NoV. RNA-dependent RNA polymerase (RdRp) and the capsid protein (VP1) fragments of these positive specimens were amplified through RT-PCR and then sequenced. Results Among these 53 fecal specimens, 30 (56.6%) were positive of NoV. The homology of the RdRp segments showed high identity with the GII.P7 reference strains (93.86%), while the VP1 segments were closely related with the GII.14 (97.13%). This indicated that all the outbreaks were caused by GII.P7/GII.14 recombinant strains. The posssible recombination breakpoints of all GII.P7/GII.14 strains were mapped at position 5009 nucleotide by SimPlot analysis. Amino acid substitutions were observed both in RdRp and VP1 regions. Conclusions Three outbreaks of NoV were caused by the same recombinant strain which suggested that GII.P7/GII.14 recombinant strains were more highly infectious and may cause more outbreaks. Hence, it's important to strengthen epidemic surveillance and take some prevention measures.