title: [Sequence analysis of cloned duck hepatitis B virus genome from a Chongqing brown duck].
abstract: OBJECTIVE
  To clone and analyze duck hepatitis B virus genome from Chongqing brown duck.
  
  
  METHODS
  Duck hepatitis B virus (DHBV) DNA extracted from a Chongqing brown duck was amplified by PCR and cloned into PGEM-T vector using T-A clone method. The sequence of this DHBV genome was analyzed with some softwares after identified.
  
  
  RESULTS
  The duck hepatitis B virus genome from Chongqing brown duck (DHBVcq), which was 3 024 nucleotides long, contained three ORFs whose onset and end nucleotides were in accord with those of HPUGA, encoding P, PreC/C and PreS/S protein respectively. Comparison of this strain with other DHBV reported in GenBank showed that the homology of DHBVcq and M32990 got the highest score of 94.9% at nucleotide level, while DHBVcq and DHBVCG got the least (89.8%). Most of the conserved regulation nucleotides and amino acids sequence found in other DHBV were also identified in DHBVcq. The epsilon region of DHBVcq, which was important for encapsidation of pgRNA and synthesis of minus-strand DNA, differed from that of most other DHBV strains, forming a stem-loop conformation with a three- nucleotides upper stem rather than a common nine-nucleotides one in free status.
  
  
  CONCLUSIONS
  The successful clone and analysis of DHBVcq provide further studies with helpful information.
authors.affiliation: Institute of Viral Hepatitis, Chongqing University of Medical Sciences, Chongqing 400010, China.
authors.forename: Ji-li
authors.initials: JL
authors.lastname: Hu
authors.forename: Ni
authors.initials: N
authors.lastname: Tang
authors.forename: Ai-long
authors.initials: AL
authors.lastname: Huang
mesh_terms: D000818:Animals; D003001:Cloning, Molecular; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics*; D004372:Ducks; D015611:Hepatitis B Virus, Duck / Q000145:classification / Q000235:genetics*; D004371:Hepatitis Virus, Duck / Q000235:genetics*; D016366:Open Reading Frames; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D017385:Sequence Homology
chemical_list: D004279:DNA, Viral