小分子乙型肝炎病毒基因组缺失突变体结构分析

目的 了解小分子HBV基因组缺失突变体的基因结构及特点.方法 采用一步法PCR从慢性乙型肝炎患者血清中扩增全基因组HBV DNA,回收并克隆＜1 kh的小分子HBV DNA,测序并以BioEdit及VectorNTI 6.0软件分析基因结构特点.结果 获得基因长度介于174～986 bp之间的64种、共124个小分子HBV缺失突变体DNA,按基因结构特点分为3类,即3种GT-AG剪接变异体、29种"常规"缺失突变体及32种基因组内部含polyA的缺失突变体.所有小分子基因组缺失突变体在HBV各编码区及基因调控区均存在不同程度缺失,其中66%(42/64种)保留与HBV复制(包装)相关的所有顺式调控序列,48%(31/64种)保留X编码区.结论 乙型肝炎患者血清中普遍存在小分子HBV基因组缺失突变体,深入了解这些变异体的结构和功能,有助于进一步探索HBV的致病机制.

Structural analysis of small deletion mutants of hepatitis B virus

Objective To elucidate the genome organization of small deletion mutants of hepatitis B virus(HBV).Methods Amplified the HBV genomes by polymerase chain reaction from the serum of the patients with chronic hepatitis B and cloned the small HBV DNA less than 1 kb,then sequenced and analyzed the gene organization of these small deletion mutants of HBV.Results Totally one hundred and twenty-four small deletion mutants of HBV genomes categorized to sixty-four types were obtained and classified into three groups according to the criteria of the characteristics of gene organization,for example,spliced variants,regular deletion mutants and the deletion mutants with an internal poly (dA).All of these isolated mutants shared some common features as the deletion in coding regions and regulatory elements,66% of the mutants retained the cis elements crucial for the viral replication and encapsidation,while 48% retained the X region.Conclusions Small deletion mutants of HBV are commonly detected in the serum from chronic hepatitis B patients,the characteristic structure of such mutants implies that they might be closely co-related with the pathogenicity of HBV.The exact mechanisms need further study yet.