GII.3型诺如病毒GZ31597株变异情况及与受体组织血型抗原结合模式分析

诺如病毒(Noroviruses,NoVs)是引起非菌型胃肠炎暴发流行的主要病原体之一。为了解我国GII.3型NoVs毒株的变异以及受体结合模式,本研究对来自2015年一起中国广州NoVs胃肠炎暴发的GII.3型毒株GZ31597株进行聚合酶区和完整VP1区基因扩增、序列测定和序列分析,并表达VP1突出区蛋白(P蛋白),通过P蛋白与不同血型唾液样本的酶免疫分析法(EIA)测定实验确定其组织血型抗原(Histo-blood group antigens,HBGAs)结合模式。GZ31597株聚合酶和VP1基因系统进化分析表明,GZ31597株为GII.P12/GII.3-SubD基因型(聚合酶/衣壳区),该毒株较先前的GII.3毒株相比,在既是抗原表位又是HBGAs受体结合位点的氨基酸385残基发生了氨基酸转换。根据Western Blotting结果,证实P蛋白成功表达。唾液结合分析结果显示,该毒株P蛋白与A、B、AB、O型分泌型以及O型非分泌型唾液均可以结合,但结合值相对低。本研究表明该GII.P12/GII.3-SubD亚型的GII.3毒株在长期的流行过程中,通过氨基酸的转换,改变抗原性和受体结合活性,使GII.3型毒株在人群中继续流行。通过探索GII.3型NoVs在人群中长期广泛流行的原因,为GII.3型诺如病毒性胃肠炎的预防和控制提供重要依据。

Analyses of Variation of Norovirus GII.3 strain GZ 31597 and Its Binding Profile with Human Histo-blood Group Antigens

Norovirus(NoVs) is the main cause of viral gastroenteritis worldwide. To understand variation of the GII.3 strain and its binding profile with human histo-blood group antigens(HBGAs), the partial RNA-dependent RNA polymerase(RdRp) sequence and complete VP1 sequence of the GII.3 strain GZ31597 isolated from an outbreak by NoVs in Guangzhou, China, in 2015 were amplified, sequenced and analyzed. Meanwhile, the protruding(P) domain in VP1 was expressed. The HBGAs binding profile of P protein with a panel of saliva samples(from which the blood type had been identified previously) was determined by an enzyme immunoassay. Phlylogenetic analyses in RdRp and VP1 indicated that the GZ31597 strain was genotyped into GII.P12/GII.3-SubD(RdRp/Capsid). Compared with previous GII.P12/GII.3-SubD strains, there was a switch at the amino-acid residue 385, which has antigen epitope and HBGAs receptor binding sites. The result of saliva binding showed that P protein was bound positively to A, B, AB, O secretors and O non-secretor, but the binding value was relatively low. The present study suggested that the GII.P12/GII.3-SubD genotype had changed its antigenicity and receptor-binding profile by switching amino-acids sites in the long-term epidemic process to continue to resist in the human population and explored why the GII.3 strain could prevail for such a long time in the population, and provides an important scientific basis for the prevention and treatment of viral diarrhea caused by the GII.3 strain.