PCR结合单酶切对戊型肝炎病毒进行基因分型的研究

Genotyping of hepatitis E virus by PCR combining with single restriction endonuclease analysis

目的 建立PCR结合单酶切对戊型肝炎病毒(HEV)进行基因分型的方法,并将其应用于HEV基因型分布的研究。方法 采用简并引物扩增1～4型HEVORF1片段,1、2型HEVPCR产物为2 75、2 6 9bp ,3、4型PCR产物为317、314bp ,分别应用NaeⅠ、NotⅠ消化两种长度的PCR产物,根据酶切结果区分4种基因型。结果 采用此方法对4种基因型的HEV标准株分型,结果与预期一致;4 3份HEVIgM阳性的临床标本中,19份PCR阳性,分型结果均为4型HEV。结论 此方法可以快速简便地区分HEV 4种基因型。南京地区散发戊型肝炎大多由4型HEV所致。

Objective To develop a simple method for genotyping of hepatitis E virus (HEV) and to investigate HEV genotype distribution in Nanjing area. Methods Twenty-seven full HEV sequences currently-available in GenBank were analyzed with MegAlign and MapDraw programs of DNA STAR software. Degenerate primers were designed and applied to amplify a fragment in HEV ORF1 region. HEV genotypes were determined by the size of the PCR products and by single restriction endonuclease analysis. Results The PCR products of HEV genotype 1 and 2 were 275 bp and 269 bp in size. Distinctively, the PCR products of genotype 3 and 4 were 317 bp and 314 bp in size. Moreover, the PCR products of genotype 1 could be digested by Nae Ⅰ, but the products of genotype 2 could not. Distinctively, the PCR products of HEV genotype 3 could be digested by Not Ⅰ, but the products of genotype 4 could not. Six HEV reference strains standing for different HEV genotypes were clustered into their own types as predicted. Within 43 HEV IgM-positive clinical specimens collected in Nanjing,19 were HEV PCR-positive and identified as genotype 4. Conclusion A simple method of PCR combined with single restriction endonuclease analysis is developed for HEV genotyping. This assay allows rapid identification of a large number of HEV isolates directly from clinical specimens. Among patients with hepatitis E in Nanjing, most were infected with HEV genotype 4.