title: Prediction of breakthrough hepatitis due to lamivudine-resistant hepatitis B virus by a sensitive semiquantitative assay using peptide nucleic acids.
abstract: OBJECTIVE
  The aim of this study was to predict breakthrough hepatitis and analyze the dynamics of lamivudine-resistant hepatitis B virus in patients treated with lamivudine.
  
  
  METHODS
  Fifty-five chronic hepatitis B patients treated with lamivudine were included. The emergence of YMDD motif mutants was detected by peptide nucleic acid (PNA) mediated PCR clamping with a detection limit of 10(1) YMDD mutants. We then performed a semiquantitative PCR assay of subjects in whom YMDD mutants were detected. This assay detects 10(2.7)-10(7.7) copies of mutant virus per 1 ml of serum.
  
  
  RESULTS
  YMDD mutants were detected in 28 (51%) of the 55 patients. Eight patients stopped medication before viral breakthrough. YMDD mutants appeared transiently despite the continuance of lamivudine therapy in 12 patients. In all 8 patients with breakthrough hepatitis, the quantities of YMDD mutants ranged from 10(2.7)-10(4.7) copies/ml in the two to three months before clinical breakthrough. In contrast, in 12 patients without viral breakthrough, there were always less than 10(2.7) copies/ml YMDD mutants.
  
  
  CONCLUSIONS
  Lamivudine-resistant viruses sometimes disappear even during lamivudine administration. Our sensitive quantitative assay proved useful for early detection of YMDD mutants and a threshold of 10(2.7) copies/ml is suggested for predicting viral breakthrough.
authors.affiliation: Molecular Gastroenterology and Hepatology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi, Kyoto, Japan. minami@koto.kpu-m.ac.jp
authors.forename: Kojiro
authors.initials: K
authors.lastname: Mori
authors.forename: Masahito
authors.initials: M
authors.lastname: Minami
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Kirishima
authors.forename: Koji
authors.initials: K
authors.lastname: Kunimoto
authors.forename: Mika
authors.initials: M
authors.lastname: Okita
authors.forename: Mika
authors.initials: M
authors.lastname: Nakayama
authors.forename: Akiko
authors.initials: A
authors.lastname: Makiyama
authors.forename: Junko
authors.initials: J
authors.lastname: Yamaoka
authors.forename: Tomoki
authors.initials: T
authors.lastname: Nakajima
authors.forename: Kohichiroh
authors.initials: K
authors.lastname: Yasui
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Itoh
authors.forename: Takeshi
authors.initials: T
authors.lastname: Okanoue
mesh_terms: D000328:Adult; D000368:Aged; D004252:DNA Mutational Analysis; D024882:Drug Resistance, Viral / Q000235:genetics*; D005260:Female; D006515:Hepatitis B virus / Q000187:drug effects / Q000235:genetics*; D019694:Hepatitis B, Chronic / Q000188:drug therapy* / Q000821:virology; D006801:Humans; D019259:Lamivudine / Q000494:pharmacology / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D020135:Peptide Nucleic Acids; D016133:Polymerase Chain Reaction / Q000379:methods; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D013997:Time Factors
chemical_list: D020135:Peptide Nucleic Acids; D018894:Reverse Transcriptase Inhibitors; D019259:Lamivudine