title: [Drug-resistant genes at hepatitis B virus polymerase region during entecavir treatment].
abstract: OBJECTIVE
  To investigate the drug-resistant genes at hepatitis B virus (HBV) polymerase region during entecavir (ETV) treatment.
  
  
  METHODS
  Serum samples from chronic hepatitis B patients with virologic breakthrough during enticavir therapy were studied. The resistant mutation patterns in the polymerase gene of hepatitis B virus were analyzed using the polymerase chain reaction (PCR)-sequencing method.
  
  
  RESULTS
  ETV resistance was detected from 19 out of 29 ETV-refractory patients, among whom 16 (84.2%) had a history of lamivudine-refractory. The mutation patterns were diverse, while rtL180 + rtM204 + rtT184 (58.6%, 17/29) was most common in patients with ETV genotype resistance. Four of 7 patients (7/29, 24.1%) with genotype B were detected to have ETV genotype resistance, while 15 of 22 patients (22/29, 75.9%) with genotype C were detected to have ETV genotype resistance. The rate of ETV genotype resistance was 57.1% (4/7) and 68.2% (15/22) in patients with genotype B and genotype C,while no statistical difference was found(P = 0.665).
  
  
  CONCLUSIONS
  ETV genotype resistance is more common in patients who have been refractory to ETV and lamivudine sequential treatment. rtM204+rtL180+rtT184 mutation is common in genotype B and C ETV resistance patients.
authors.affiliation: Department of Infectious Diseases, Hangzhou Xixi Hospital, Hangzhou, China.
authors.forename: Xiao-feng
authors.initials: XF
authors.lastname: Guo
authors.forename: Chao-xian
authors.initials: CX
authors.lastname: Zhang
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.forename: Fei
authors.initials: F
authors.lastname: Wu
authors.forename: Xin
authors.initials: X
authors.lastname: Luo
mesh_terms: D000328:Adult; D000998:Antiviral Agents / Q000627:therapeutic use; D004279:DNA, Viral / Q000097:blood / Q000235:genetics; D004259:DNA-Directed DNA Polymerase / Q000235:genetics*; D024882:Drug Resistance, Viral / Q000235:genetics*; D005260:Female; D006147:Guanine / Q000031:analogs & derivatives / Q000627:therapeutic use; D006515:Hepatitis B virus / Q000201:enzymology / Q000235:genetics*; D019694:Hepatitis B, Chronic / Q000188:drug therapy / Q000821:virology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D014764:Viral Proteins / Q000235:genetics*; D055815:Young Adult
chemical_list: D000998:Antiviral Agents; D004279:DNA, Viral; D014764:Viral Proteins; C413685:entecavir; D006147:Guanine; D004259:DNA-Directed DNA Polymerase