title: Early detection and quantification of lamivudine-resistant hepatitis B virus mutants by fluorescent biprobe hybridization assay in lamivudine-treated patients.
abstract: BACKGROUND
  Long-term lamivudine treatment induces the emergence of lamivudine-resistant hepatitis B virus (HBV). The objective of this study was to develop a fluorescent biprobe hybridization (FBH) assay for the detection and quantification of HBV mutants in the clinical course of lamivudine-treated patients and to evaluate its clinical usefulness.
  
  
  METHODS
  We developed an FBH assay to detect mutations in the HBV DNA polymerase gene. The assay's detection sensitivity was determined using a dilution series of wild-type/mutant plasmid DNA. Blood samples obtained from 27 lamivudine-treated patients were analyzed.
  
  
  RESULTS
  Mutant DNA levels as low as 10% of total HBV DNA were detected (sensitivity = 100%, specificity = 80%). HBV mutants were detected in five of the 27 patients during an average follow-up of 20 months after lamivudine administration. In one of the five patients, the YIDD mutant was detected at the initiation of lamivudine treatment, while the remaining four patients were identified as having YIDD mutants within 3 months after beginning lamivudine administration. Of the five patients with an HBV mutant, four developed breakthrough hepatitis more than 10 months after the detection of HBV mutants, following the reappearance or a re-increase of HBV DNA, characterized by a predominance of the mutant. The YIDD mutant was detected in one patient, even when the titer of the serum HBV DNA was below the detection limit of commercially available quantitative polymerase chain reaction.
  
  
  CONCLUSIONS
  The FBH assay is an efficient method for detecting and quantifying HBV mutants, as early as 3 months after lamivudine administration.
authors.affiliation: Department of Gastroenterology and Hepatology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Okayama, 700-8558, Japan.
authors.forename: Fumi
authors.initials: F
authors.lastname: Umeoka
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Iwasaki
authors.forename: Masayuki
authors.initials: M
authors.lastname: Matsumura
authors.forename: Akinobu
authors.initials: A
authors.lastname: Takaki
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Kobashi
authors.forename: Masashi
authors.initials: M
authors.lastname: Tatsukawa
authors.forename: Hidenori
authors.initials: H
authors.lastname: Shiraha
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Fujioka
authors.forename: Kohsaku
authors.initials: K
authors.lastname: Sakaguchi
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Shiratori
mesh_terms: D000328:Adult; D000998:Antiviral Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D015342:DNA Probes; D004259:DNA-Directed DNA Polymerase / Q000235:genetics; D024882:Drug Resistance, Viral / Q000235:genetics*; D005260:Female; D005470:Fluorometry; D006515:Hepatitis B virus / Q000187:drug effects* / Q000235:genetics; D019694:Hepatitis B, Chronic / Q000188:drug therapy* / Q000821:virology; D006801:Humans; D019259:Lamivudine / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009693:Nucleic Acid Hybridization / Q000379:methods; D012680:Sensitivity and Specificity; D044366:Transition Temperature
chemical_list: D000998:Antiviral Agents; D015342:DNA Probes; D019259:Lamivudine; D004259:DNA-Directed DNA Polymerase