Objective   To investigate the characteristic of a complete HBV genome.

  Methods   The genotypes of HBV were determinated by PCR genoty ping, and the complete HBV genome was amplified through three over lapping segments amplification from the serum of a randomly selected patient infected with genotype C of HBV alone.The three amplicons were cloned into pGEM-T easy vector and 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 analysis with Vector NTI Suite 7.0, GeneDoc 2.6 and TreeView1.5.

  Results   The genome of BDHB1 was 3215 bp long and the base A, G, C and T were 22.2%, 22.4%, 26.8% and 28.6%, respectively.It contained four over lapping open reading frames(ORFs): S, C, P and X region.Its HBsAg subtype was adr.There was no YMDD mutation in codons 549-552aa of RT region.No mutation occured at nt1896 in the precore region.A to T and G to A continuous mutations were detected atnt 1 762 and 1 764 in the BCP(Basic Core Promoter)region.Phylogenetic 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 to HBV genotype C.There were double mutations in BCP region of the strain.The overlapping segments amplification and splicing could be one of methods for the complete genome analysis.