贵州省2019-2021年人源和猪源戊型肝炎病毒基因特征

Genetic characteristics of hepatitis E virus from humans and swine in Guizhou province during 2019-2021

目的分析贵州省部分地区人源和猪源戊型肝炎病毒(Hepatitis E virus,HEV)流行株基因特征。方法2019-2021年在贵州省医疗机构收集急性HEV感染者(抗-HEV IgM阳性)血清标本,在屠宰场收集猪胆汁和血清标本,提取HEV核酸,对HEV ORF2区基因进行扩增和测序,构建系统进化树,分析基因型、基因亚型及其核苷酸和氨基酸同源性。结果从450例急性HEV感染者标本和196份猪标本中共获得53条人源和2条猪源HEV序列。人源序列的核苷酸和氨基酸同源性分别为81.39%-100%和95.92%-100%,猪源序列分别为87.40%和100%;人源和猪源HEV均与HEV基因4型参考株的核苷酸同源性最高,分别为89.93%和89.83%。55条HEV序列位于系统进化树的3个分支,其中24条与4b亚型、20条与4a亚型、11条与4d亚型参考株处于同一分支,且核苷酸同源性最高,分别为95.54%、93.10%、95.72%。2条人源序列各发生1个位点的氨基酸替换。结论2019-2021年贵州省部分地区人群和猪群中HEV优势流行株为基因4型,包括4b、4a和4d亚型,氨基酸序列相对保守;可能存在跨种传播。

Objective To explore genetic characteristics of hepatitis E virus(HEV)strains from humans and swine in areas of Guizhou province.Methods We collected serum samples from people with acute HEV infection(positive to anti-HEV IgM)in hospitals,and bile or serum samples from swine in slaughterhouses in Guizhou from 2019 to 2021.We extracted HEV nucleic acid,amplified genes in the HEV ORF2 region using the nested RT-PCR,conducted sequence analyses,and constructed phylogenetic trees.We identified genotypes and sub-genotypes of HEV strains and analyzed nucleotide and amino acid homologies.Results A total of 53 human and 2 swine HEV sequences were obtained from 450 specimens from people with acute HEV infection and 196 specimens from swine,respectively.Nucleotide and amino acid homologies were 81.39%-100% and 95.92%-100% within human sequences and 87.40% and 100% within swine sequences.Nucleotide homologies of both human and swine HEV sequences were highest compared with the genotype 4 reference strain,at 89.93% and 89.83%,respectively.All 55 HEV sequences were located in three branches of the phylogenetic tree,24,20,and 11 in branches of subgenotypes 4b,4a,and 4d with the highest nucleotide homologies being 95.54%,93.10%,and 95.72%,respectively.One amino acid substitution occurred in each of two human sequences.Conclusions HEV genotype 4,including subgenotypes 4b,4a,and 4d,was the predominate circulating genotype among humans and swine during 2019-2021 in areas of Guizhou,with amino acid sequences being conserved.HEV may spread across species.