C型乙型肝炎病毒的全基因组序列分析

目的 探索乙型肝炎病毒(HBV)全基因组的结构特点。方法 应用直接PCR基因分型法确定HBV基因型。然后随机选择1例单纯HBVC基因型感染的患血清，分3个相互重叠片段扩增HBV基因并分别克隆测序。利用Vector NTI Suite7．0软件包、GeneDoc2．6和TreeView1．5，将该3个基因片段拼接为全基因组序列，命名为BDHBl，并进行基因进化树分析和同源性比较。结果 HBVC基因型序列全长为3215bp，其中A占22．2％，G占22．4％。C占26．8％。T占28．6％；有S、C、P和X区4个开放读码框架(ORFs)；HBsAg亚型为adr；HBVRT区549～552aa为YMDD，未发生变异；未发现前C区：ntl896G变异：BCP区ntl762、1764发生双突变。对HBV分段序列及全基因组序列进行基因进化树分析显示，BDHBl与HBVVC基因型的同源性最高。结论 BDHBl基因组符合HBVC基因型结构特点，在BCP区存在双突变。分片段扩增再拼接可作为全基因组序列分析方法之一。

Complete genome sequence analysis of HBV genotype C strain

Objective To investigate the characteristic of a complete HBV genome. Methods The genotypes of HBV were determinated by PCR gen otyping,and the complete HBV genome was amplified through three overlapping segm ents amplification from the serum of a randomly selected patient infected with g enotype C of HBV alone.The three amplicons were cloned into pGEM-T easy vector a nd sequenced.The sequences of the three amplicons were spliced as a complete HBV genome named as BDHB1,and then analyzed for phylogenetic tree and homologous an alysis with Vector NTI Suite 7.0,GeneDoc 2 6 and TreeView1.5. Results The genome of BDHB1 was 3215?bp long and the bas e A, G,C and T were 22 2%,22.4%,26.8% and 28.6%,respectively.It contained four o v erlapping open reading frames (ORFs):S,C,P and X region.Its HBsAg subtype was ad r.There was no YMDD mutation in codons 549-552aa of RT region.No mutation occure d at nt1896 in the precore region.A to T and G to A continuous mutations were de tected at nt1?762 and 1?764 in the BCP (Basic Core Promoter) region.Phylogenet ic tree analysis of the overlapping segments and the complete genome both showed that BDHB1 was most homologous with HBV genotype C. Conclusion The characteristic of BDHB1 was most similar t o HBV genotype C.There were double mutations in BCP region of the strain.The ove rlapping segments amplification and splicing could be one of methods for the com plete genome analysis.