孕产妇感染的乙型肝炎病毒表面抗原基因的分子特征

Molecular characteristics of surface antigen gene of Heptitis B virus infecting puerpera women

目的:通过调查孕产妇慢性感染的乙型肝炎病毒表面抗原基因特征,分析与HBV母婴传播相关的病毒因素。方法:收集在江西省妇幼保健院待产的518份孕产妇血清。ELISA法筛查HBV感染者,抽提血清中HBV DNA,采用PCR扩增HBV S基因并测序,利用Genotyping软件对PCR产物序列进行HBV分型。应用Clustal X和Bioedit软件将不同感染者的HBV S基因核苷酸与参考序列进行多重比对,分析HBV S基因的突变和HBV亚型。结果:518例孕产妇中17例HBV阳性感染,13例标本PCR反应阳性,PCR产物测序结果显示均为HBV S基因,10例感染B基因型HBV,属于adw亚型;3例感染C基因型HBV,属于adr亚型;序列比对分析结果显示,5例标本在"a"抗原决定簇序列上出现三种形式变异,2例为A530G→T126A,1例为A541C→Q129H,2例为G587A→G145;1例Pres2区出现密码子缺失突变。结论:江西地区孕产妇主要感染B和C基因型HBV;在表面抗原"a"抗原决定簇上有点突变出现,可能是母婴传播,逃避疫苗免疫保护的一种机制。

Objective： To elucidate molecular mechanisma associated with maternal-infant transmission of HBV by analyzing the molecular characteristics of surface antigen gene of Hepatitis B virus infecting puerpera women in Jiangxi Province. Methods： The sera of 518 puerpera women were collected for detection of HBV infection. HBV DNA was extracted for PCR amplification of S gene of HBV. The PCR products of HBV S gene were sequenced for analysis of genotype of HBV. Clustal X and Bioedit software were used to align the sequence of S gene to analyze the mutation sites in Pre S1,Pre S2 and HBs Ag proteins. Result： 17 positive sera of HBV infection were screened from 518 sera. 13 positive products were amplified from 17 sera with PCR method and were found to be HBV S gene after sequence analysis. Among 13 cases of HBV infection,10 were infected with genotype B HBV of belonging to adw serotype and 3 infected with genotype C HBV of adr serotype. Mutiple sequnces alignment showed that there were three types of variation occurring at ＂a＂antigen determinant of 5 infection cases. There were two cases of A530G→ T126 A,one case of A541C→Q129H and two cases of G587A→G145.One case with loss of start codon in Pre S2 was found. Conclusions： The puerpera women were mainly infected with genotype B and C HBV in Jiangxi. The site mutations occuring on ＂a＂determinant of HBs Ag may contribute to the maternal-infantile transmission of HBV and escape from protection of vaccine immunization.