title: Mutations in hepatitis B DNA polymerase associated with resistance to lamivudine do not confer resistance to adefovir in vitro.
abstract: To determine whether adefovir is active against lamivudine-resistant hepatitis B virus (HBV), the inhibition constants of adefovir diphosphate and lamivudine triphosphate for wild-type and mutant human HBV DNA polymerases, which contain amino acid substitutions associated with lamivudine resistance, were compared. Recombinant wild-type and mutant human HBV DNA polymerases were expressed and substantially purified using a baculovirus expression system and immunoaffinity chromatography. HBV DNA polymerase mutants M552I, M552V, and L528M/M552V showed resistance to lamivudine triphosphate with inhibition constants (Ki) increased by 8.0-fold, 19.6-fold, and 25.2-fold compared with that of wild-type HBV DNA polymerase. However, these mutants remained sensitive to adefovir diphosphate with the inhibition constants increasing by 1.3-fold and 2.2-fold or decreasing by 0.79-fold. The L528M single mutation, identified in patients with increasing HBV DNA levels during therapy with famciclovir, also remained sensitive to adefovir diphosphate with the inhibition constant increased by only 2.3-fold.
authors.affiliation: Gilead Sciences, Foster City, CA, USA.
authors.forename: X
authors.initials: X
authors.lastname: Xiong
authors.forename: C
authors.initials: C
authors.lastname: Flores
authors.forename: H
authors.initials: H
authors.lastname: Yang
authors.forename: J J
authors.initials: JJ
authors.lastname: Toole
authors.forename: C S
authors.initials: CS
authors.lastname: Gibbs
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000595:Amino Acid Sequence; D019380:Anti-HIV Agents / Q000494:pharmacology*; D016367:Baculoviridae; D004259:DNA-Directed DNA Polymerase / Q000235:genetics*; D004351:Drug Resistance / Q000502:physiology; D006515:Hepatitis B virus / Q000235:genetics*; D006801:Humans; D019259:Lamivudine / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009154:Mutation / Q000502:physiology*; D063065:Organophosphonates; D011994:Recombinant Proteins
chemical_list: D019380:Anti-HIV Agents; D063065:Organophosphonates; D011994:Recombinant Proteins; D019259:Lamivudine; C053001:adefovir; D004259:DNA-Directed DNA Polymerase; D000225:Adenine