广西地区猪肠病毒G型的流行病学调查及VP1基因序列分析

为分析广西地区猪肠病毒G型（EV-G）的流行状况及分子遗传演化特征，本研究收集2017－2018年广西地区222份临床腹泻样品，进行EV-G的检测、流行病学调查及VP1基因的扩增、克隆和序列分析。流行病学调查结果显示，广西地区2017－2018年EV-G的样品阳性率为6.76%（15/222），而猪场阳性率则高达16.98%（9/53）。值得注意的是，广西地区2017－2018年EV-G的样品阳性率从2017年的4.55%上升至2018年的10.00%，上升幅度较大。同时发现该病毒在冬春季节的检出率较高。序列同源性分析结果显示，本研究获得的2株EV-G VP1基因之间的核苷酸同源性为99.2%，氨基酸同源性为98.8%，与国内外毒株VP1基因的核苷酸同源性为62.4%~80.1%，氨基酸同源性为45.7%~71.7%。遗传进化分析显示，本研究获得的2株EV-G VP1序列在同一分支，均属于G1亚型，与美国分离株13-03212遗传关系密切。氨基酸序列比较结果显示，广西地区该2株EV-G VP1氨基酸在多个位点发生了变异。抗原指数分析显示，广西地区EV-G型流行毒株的抗原性变化较大。表明2017－2018年广西地区存在一定程度的EV-G感染，本研究结果为明确EV-G型的流行概况及EV-G型的分子特性提供了参考依据。

Epidemiological Investigation and VP1 Gene Sequence Analysis of Porcine Enterovirus Type G in Guangxi

To analyze the prevalence and molecular genetic evolution of porcime enterovirus G (EV-G) in Guangxi,222 clinical diarrhea samples were collected in Guangxi from 2017 to 2018 in this study,EV-G detection and epidemiological investigation were conducted,as well as VP1 gene amplification,cloning and sequence analysis.According to the results of epidemiological survey,the positive rate of EV-G samples in Guangxi from 2017 to 2018 was 6.76% (15/222),while the positive rate of pig farms was as high as 16.98% (9/53).It was noteworthy that the positive rate of EV-G samples in Guangxi had increased from 4.55% in 2017 to 10.00% in 2018,which showed a significant increase.At the same time,the detection rate of this virus was higher in winter and spring.Sequence homology analysis showed that the nucleotide homology between the two EV-G VP1 genes obtained in this study was 99.2% and the amino acid homology was 98.8%.Compared with domestic and foreign strains,the nucleotide and amino acid identity was 62.4% to 80.1% and 45.7% to 71.7%,respectively.Genetic evolution analysis showed that the two EV-G VP1 sequences obtained in this study both belonged to the G1 subtype in the same branch,and were closely related to the American isolate 13-03212. The results of amino acid sequence comparison showed that the two strains of EV-G VP1 had great variation at multiple sites.Antigen index analysis showed that the antigenicity of EV-G in Guangxi had a large variation.The results of this study indicated that there was a certain degree of EV-G infection in Guangxi during 2017 to 2018.This study provided a reference for the EV-G epidemic profile and the molecular characteristics of EV-G.