HBsAg与抗-HBs同时阳性者体内S基因序列分析

Analysis on S-gene Sequence of Patients with Positive HBsAg and Anti-HBs Simultaneously

目的 报告乙型肝炎病毒 (HBV)表面抗原 (HBsAg) /表面抗体 (抗 -HBs)同时阳性患者血清中S区编码碱基序列及其氨基酸序列的变异特点。方法 以adr亚型的HBV基因序列为依据 ,设计特异性多聚酶链反应 (PCR)引物 ,自 2例HBsAg/抗 -HBs均阳性的患者体内扩增HBV全S基因片段 ,克隆入pGEMTasy质粒 ,DNA测序确定病毒的变异特点。结果 测序结果发现双阳患者与HBsAg阳性患者血清中的HBV全S基因比较 ,核苷酸序列有 4个核苷酸位点 (0 3% )的替换突变 ,表面抗原氨基酸序列无特异性替换突变 ,但HBV多聚酶的间隔区氨基酸序列有 3个位点的特异性替换突变。结论 HBV长期携带者体内有HBV准种共存 :HBsAg与抗 -HBs同时阳性的原因不能归因于病毒的变异 。

Objective To clarity the characteristics of mutations in HBV S nucleotides and amino acid sequences from the patients with chronic HBV infection, whose serum were detected both HBsAg and anti-HBs positive.Methods A set of specific primers were synthesized according to HBV DNA sequence of adr subtype, the whole S, gene was amplified from the serum of two patients and the PCR products were subcloned into pGEM Teasy vectors.Sequence comparison was made between the target sequence from the HBsAg/anti-HBs positive serum and that from HBsAg positive serum.Results Sequencing results proved the high consistency, with only 4 out of 1428 nt (0.3%) were different between the target sequence from the double positive serum and that from the HBsAg positive serum, but with no specific amino acid site difference in PreS1, PreS2 and major protein.There were 3 sites of difference in spacer region corresponding to HBV polymerase.Conclusion There were HBV quasispecies in the patients with chronic HBV infection.The phenomenon of both HBsAg and anti-HBs positive could not be attributed to mutation in HBV genome.