title: Resistance to adefovir dipivoxil in lamivudine resistant chronic hepatitis B patients treated with adefovir dipivoxil.
abstract: BACKGROUND
  Adefovir dipivoxil (ADV) is a potent nucleotide analogue against both the wild-type and lamivudine (LMV) resistant hepatitis B virus (HBV). The cumulative incidence of ADV resistant mutations in the nucleoside/-tide treatment naive chronic hepatitis B patient (CHB) at weeks 48, 96, and 144 was 0, 0.8-3%, and approximately 5.9%, respectively.
  
  
  OBJECTIVE
  The aim of this study was to characterise the genotypic and phenotypic mutation profiles to ADV in 67 LMV resistant CHB patients who were treated with ADV.
  
  
  METHODS
  Serum HBV DNA was quantified by real time polymerase chain reaction. The ADV mutant was detected using matrix assisted laser desorption/ionisation time of flight mass spectrometry based genotyping assays, termed restriction fragment mass polymorphism (RFMP).
  
  
  RESULTS
  RFMP analysis revealed that a total of 11 amino acid substitutions developed in the rt domain of the HBV polymerase in nine patients. The cumulative incidence of genotypic ADV resistance at months 12 and 24 was 6.4% and 25.4%, respectively. The rtA181V, rtN236T, and rtA181T mutations were detected in five, four, and two of the 67 patients at treatment months 12-17, 3-19, and 7-20, respectively. Serial quantification of serum HBV DNA revealed that two patients with the rtA181V mutation, with or without the rtN236T mutation, and one patient with the rtA181T mutation displayed HBV DNA rebound.
  
  
  CONCLUSIONS
  Emergence of the ADV mutation in LMV resistant patients who are treated with ADV appeared to present earlier and more frequently than was reported in previous studies on nucleoside/-tide treatment naive patients.
authors.affiliation: Korea University Medical College Guro Hospital, Department of Internal Medicine, Division of Gastroenterology and Hepatology, Guro-gu Guro-dong gil 97, Seoul, Korea.
authors.forename: J E
authors.initials: JE
authors.lastname: Yeon
authors.forename: W
authors.initials: W
authors.lastname: Yoo
authors.forename: S P
authors.initials: SP
authors.lastname: Hong
authors.forename: Y J
authors.initials: YJ
authors.lastname: Chang
authors.forename: S K
authors.initials: SK
authors.lastname: Yu
authors.forename: J H
authors.initials: JH
authors.lastname: Kim
authors.forename: Y S
authors.initials: YS
authors.lastname: Seo
authors.forename: H J
authors.initials: HJ
authors.lastname: Chung
authors.forename: M S
authors.initials: MS
authors.lastname: Moon
authors.forename: S-O
authors.initials: SO
authors.lastname: Kim
authors.forename: K S
authors.initials: KS
authors.lastname: Byun
authors.forename: C H
authors.initials: CH
authors.lastname: Lee
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D000328:Adult; D024882:Drug Resistance, Viral / Q000235:genetics; D005260:Female; D005838:Genotype; D019694:Hepatitis B, Chronic / Q000188:drug therapy* / Q000235:genetics; D006801:Humans; D019259:Lamivudine / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics; D063065:Organophosphonates / Q000627:therapeutic use*; D010641:Phenotype; D012189:Retrospective Studies; D018894:Reverse Transcriptase Inhibitors / Q000627:therapeutic use*
chemical_list: D063065:Organophosphonates; D018894:Reverse Transcriptase Inhibitors; D019259:Lamivudine; D000225:Adenine; C106812:adefovir dipivoxil