母婴传播感染HBV儿童及其母亲体内HBV preS/S基因准种序列以及变异特点研究  

The study on the quasispecies sequence of preS/S of hepatitis B virus in children infected by vertical transmission and their mothers

作　　者：许红梅[1] 任红[2] 彭明利[2] 凌宁[2] 卿玉玲[2] 

机构地区：[1]重庆医科大学儿童医院,400014 [2]重庆医科大学病毒性肝炎研究所

出　　处：《中华微生物学和免疫学杂志》2003年第3期173-177,共5页Chinese Journal of Microbiology and Immunology

基　　金：国家自然科学基金资助项目 ( 396 30 2 80 )

摘　　要：目的　对经母婴传播获得乙型肝炎病毒 (HBV)感染子女及其母亲无症状携带者 (AsC)体内HBVpreS S基因进行研究 ,了解来源相同的HBV毒株在不同程度病毒血症情况下preS S有无准种存在及其特点。方法　应用T A克隆技术构建重组质粒pGEM preS S、双酶切进行鉴定 ,每个病人选 6个酶切鉴定正确的克隆测序并进行分析。结果　 3对AsC母子呈不同程度病毒血症 ,HBV均为基因型B 血清型adw2。 36个克隆序列建立的进化树显示 3对母子的preS S为同一分支HBVpreS S进化而来 ,每例病人 6个序列呈准种分布。低病毒血症HBVpreS S的核苷酸变异率明显高于高病毒血症 ,2个低病毒血症病人的变异位点绝大多数相同 ,其中错义变异多位于T 细胞表位和B 细胞表位内或 和附近。变异率和变异位点均与年龄无关。结论　经母婴传播而获得HBV感染儿童及其母亲无症状携带者 ,无论病毒血症高低 ,体内HBVpreS S序列均呈准种分布。来源相同的HBVpreS S在不同程度病毒血症病人体内差异较大 ,而与年龄无关。高病毒血症病人变异率低 ,而在低病毒血症变异率较高 ,但变异是有规律的 ,可能与免疫逃逸有关。Objective To investigate quasispecies populations of HBV in AsC (asymptomatic carrier) children infected by vertical transmission and their AsC mothers with different severity of viremia. Methods Three pairs of child and mother were included in this study. Mothers of all children were AsC before pregnancy and the children did not vaccinated against HBV at birth. Anti-HBV medicine was never administrated to all subjects. The serological markers of hepatitis A, B, C, D and E virus were tested and the titers of serum HBV DNA were quantitated. preS/S gene was amplified by PCR and cloned into pGEM-T vector with T-A cloning technique. The recombinant plasmid pGEM-preS/S was confirmed by digestion with restriction enzyme ApaⅠand SacⅠ. Six clones were selected to be sequenced each patient. Phylogenetic tree was established based on the 36 clones of HBV preS/S gene. The sequences were analyzed comparing with consensus sequence of Chongqing. Results HBV strains of all subjects were subtype B/adw2. Phylogenetic tree showed that the preS/S gene of HBV in each pair of child and mother came from a same branch. The sequences of preS/S gene of six clones were not same, but there was a limited evolutive space and there was a dominant strain in every patient. The evolutive distances of preS/S gene in patients with low virus load were farther and the differences among 6 clones were more than those with high virus load. Substitution was the main mutation model. The mutation rates in low load patients (8.04%-8.19%) were much higher than those in high load patients (1.12%- 1.41% ). There were 40 mutational positions and there was no mutational hotspot in high load patients. In two low load patients, there were 105 and 103 mutations respectively. Conclusions There are HBV quasispecies populations in the sera of AsC children infected through mother-to-infant transmission and their AsC mothers with different degree of viremia. When HBV from a same branch is in different hosts with different degree of viremia, there are many dif

关 键 词：乙型肝炎病毒 preS/S 母婴传播 准种 

分 类 号：R346[医药卫生—基础医学]