经母婴传播获得HBV感染儿童及其母亲体内HBV EnhII/CP/PreC基因变异研究

The study on the EnhII/CP/PreC gene mutation of hepatitis B virus in children infected by mother-to-infant transmission and their mother

目的:通过对经母婴传播获得HBV感染的子女及其母亲慢性携带者体内HBV EnhII/CP/PreC基因序列研究,了解来源相同的HBV毒株在不同程度病毒血症情况下EnhII/CP/PreC基因变异特点。方法:选择15对母子AsC,根据HBV病毒血症高低分为3组,每组5对母子,即Ⅰ组(母子均为高病毒血症)、Ⅱ组(子女为高病毒血症、母亲为低病毒血症)和Ⅲ组(子女为低病毒血症、母亲为高病毒血症)。同对母子HBV亚型相同,各组中有4/5对母子为B/adw2、1/5对母子为C/adrq+亚型。应用T-A克隆技术构建重组质粒pGEM-EnhII/CP/PreC、双酶切鉴定,每个病人选2个酶切鉴定正确的克隆测序并分析。结果:高病毒血症组间或低病毒血症组间HBV EnhII/CP/PreC基因变异数目及位点均无明显差异,低病毒血症病人变异数目及位点明显高于高病毒血症。高病毒血症中16例B/adw2亚型的32个EnhII/CP共有6个变异位点;4例C/adrq+亚型的8个克隆中有4个变异位点,均无热点变异;PreC无变异。低病毒血症中8例B/adw2亚型病人的16个克隆共有26个变异位点,变异与年龄无关。结论经母婴传播获得HBV感染儿童及其母亲无症状携带者中,HBVEnhII/CP/PreC变异与病毒血症高低有关,低病毒血症病人变异明显高于高病毒血症。HBV的低复制状态是CP、EnhII及X蛋白等结构和功能改变综合影响的结果,与年龄无关。

Objective： To invistigate the characteristics of mutations in EnhⅡ/CP/PreC of HBV in AsC children infected through mother-to-infant transmission and their AsC mothers with different degrees of viremia. Methods： There were 15 pairs of children and mothers. They were divided into three groups based on the level of viremia： group Ⅰ （both children and mothers presented high viremia）, group Ⅱ（children presented high and mothers presented low viremia） and group Ⅲ （children presented low and mothers were high viremia）. There were 5 pairs in each group with 4/5 of HBV being B/adw2 and 1/5 of HBV being C/adrq＋ in each group. EnhII/CP/PreC was amplified and cloned into pGEM-T vector. Tow clones were selected to sequence each patient. Results： Substitution was the main model of mutations. There were no significant differences in the mutation numbers in EnhⅡ/CP/PreC among high viremia groups or between two low viremia groups. There were significant differences between each high viremia group and each low viremia group. In patients with high viremia, there were 6 mutational positions in 32 clones in 16/20 patients with B/adw2, and there were 4 mutational positions in 8 clones in 4/20 patients with C/adrq＋. In patients with low viremia （mothers of group Ⅱ and children of group Ⅲ）, there were 26 mutational positions totally. Conclusion： The mutations in EnhⅡ/CP/PreC are related to the degree of viremia in AsC children infected through mother-to-infant transmission and their AsC mothers, and no associated with age.