title: [A study on the mutation of P gene region including YMDD motif in hepatitis B virus].
abstract: OBJECTIVE
  To investigate the primary structure and heterogenenity of P gene region including YMDD motif in hepatitis B virus.
  
  
  METHODS
  From serum samples collected from 4 patients who had never been treated with anti-viral drugs, DNA fragments of 1057bp long of P gene were amplified and cloned into pUC19. Twenty positive clones were chosen randomly from each sample. The YMDD motif mutation was detected by mismatched PCR-RFLP. Finally last ten positive clones of two samples were sequenced.
  
  
  RESULTS
  Nucleotide mutation rates among clones of Sample 1 and 2 were 0.3% - 1.1%, 0.4% - 1.7%, respectively. Among 80 clones, the variations from YMDD to YMGD were revealed in two clones.
  
  
  CONCLUSIONS
  There are HBV quasispecies in the P gene region including YMDD motif of hepatitis B virus and a novel mutation of YMDD motif in the sera of patients without being therapied by anti-viral drugs.
authors.affiliation: Department of infectious deseases, Affliated Hospital of Xuzhou Medical College, XuZhou 221002,China.
authors.forename: Bo
authors.initials: B
authors.lastname: Feng
authors.forename: Lai
authors.initials: L
authors.lastname: Wei
authors.forename: Ming
authors.initials: M
authors.lastname: Chen
authors.forename: Xiu-hua
authors.initials: XH
authors.lastname: Li
mesh_terms: D000328:Adult; D020816:Amino Acid Motifs; D001483:Base Sequence; D015684:Gene Products, pol / Q000235:genetics*; D006515:Hepatitis B virus / Q000235:genetics*; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length
chemical_list: D015684:Gene Products, pol; C066027:P protein, Hepatitis B virus