HBV-DNA高水平孕妇的HBV前S和S区基因突变及基因分型

Genetic Mutations and Genotypes of HBV Pre S and S Regions in Pregnant Women with High Level Serum HBV-DNA

【目的】研究HBV-DNA高水平孕妇的HBV前S(前S1和前S2)及S区的基因突变模式和基因分型,为从病毒因素探讨HBV母婴传播免疫阻断失败提供实验基础。【方法】选取血清HBsAg阳性且HBV-DNA≥105 IU/mL的孕妇41例,提取血清HBV DNA,靶向设计HBV各基因型的前S及S区通用引物,经PCR扩增测序进行序列分析,检测和分析前S及S区基因的突变情况,并进行基因分型。【结果】①在41例样本中,共有29例(70.73%)样本存在前S1、前S2及S区基因突变,突变方式以碱基置换为主;前S1、前S2及S区基因的突变频率分别为8.96%、9.88%和3.24%,前S1和前S2区的突变频率显著高于S区(P<0.05)。②对41例样本根据S区点突变的特点进行基因分型及同源树簇集分析,结果B基因型22例,C基因型19例,两基因型在全S区的基因突变频率相比,差异无统计学意义(P>0.05);B、C两基因型分别形成独立的簇集,簇集间同源性<90%,但簇集内B、C两个基因型的同源性分别达96%和95%。【结论】①HBV-DNA高水平孕妇的HBV前S及S区的基因突变普遍存在,突变形式以碱基置换为主,突变频率以前S1和前S2区常见,S区则相对稳定;②不同HBV基因型间同源性差异较大,按HBV不同基因型分别进行前S和S区基因突变模式的分析将更有意义。

[ Objective ] To provide an experimental basis for exploring the reason of HBV maternal vertical transmission immune blocking failure, we studied the mutation profiles and genotypes of hepatitis B virus （HBV） in the Pre S and S regions of pregnant women with high level serum HBV-DNA before delivery. [Methods] HBV DNA were extracted from the serum of 41 pregnant women with HBsAg positive and HBV-DNA/〉 105 IU/mL. Based on the sequence alignment of all HBV genotypes, specific primers targeting all HBV genotypes were designed to amplify the Pre S and S regions of HBV followed by sequence analysis on the sequencing data available. [Results] 1. Among the 41 cases, 29 cases （70.73%） showed mutations in the re S and S regions, substitution was the main mutation model. Among all cases, PreS1, pre S2 and S regions mutations frequency were 8.96%, 9.88%, and 3.24%, respectively, mutation frequency in pre S1 and pre $2 regions were significantly higher than that in S region （P 〈 0.05）. 2. Genotypes based on the mutation in S region and homology tree model were analyzed. In the 41 cases, 22 cases were genotype B, and 19 cases were genotype C. The mutation frequency in the Pre S and S regions between genotype B and genotype C were not statistically significant （P 〉 0.05 ）. Genotype B and genotype C had their own clusters, homology rate was less than 90% between cluster B and cluster C, but in the cluster B and cluster C the homology rate were 96% and 95%, respectively. [Conclusion] 1. Mutations of HBV Pre S and S regions were common in pregnant women with high level serum HBV-DNA before delivery. The most common mutation in the Pre S and S regions of HBV was substitution, mutation frequency in pre S1 and pre $2 regions were higher than that in S region. 2.The homology rate between different genotypes was low, and study on the mutation pattern of HBV Pre S and S regions should be analyzed independently in each genotype.