title: Identification and characterization of clevudine-resistant mutants of hepatitis B virus isolated from chronic hepatitis B patients.
abstract: Clevudine (CLV) is a nucleoside analog with potent antiviral activity against chronic hepatitis B virus (HBV) infection. Viral resistance to CLV in patients receiving CLV therapy has not been reported. The aim of this study was to characterize CLV-resistant HBV in patients with viral breakthrough (BT) during long-term CLV therapy. The gene encoding HBV reverse transcriptase (RT) was analyzed from chronic hepatitis B patients with viral BT during CLV therapy. Sera collected from the patients at baseline and at the time of viral BT were studied. To characterize the mutations of HBV isolated from the patients, we subjected the HBV mutants to in vitro drug susceptibility assays. Several conserved mutations were identified in the RT domain during viral BT, with M204I being the most common. In vitro phenotypic analysis showed that the mutation M204I was predominantly associated with CLV resistance, whereas L229V was a compensatory mutation for the impaired replication of the M204I mutant. A quadruple mutant (L129M, V173L, M204I, and H337N) was identified that conferred greater replicative ability and strong resistance to both CLV and lamivudine. All of the CLV-resistant clones were lamivudine resistant. They were susceptible to adefovir, entecavir, and tenofovir, except for one mutant clone. In conclusion, the mutation M204I in HBV RT plays a major role in CLV resistance and leads to viral BT during long-term CLV treatment. Several conserved mutations may have a compensatory role in replication. Drug susceptibility assays reveal that adefovir and tenofovir are the most effective compounds against CLV-resistant mutants. These data may provide additional therapeutic options for CLV-resistant patients.
authors.affiliation: Department of Internal Medicine, Konkuk University School of Medicine, Seoul, South Korea.
authors.forename: So Young
authors.initials: SY
authors.lastname: Kwon
authors.forename: Yong Kwang
authors.initials: YK
authors.lastname: Park
authors.forename: Sung Hyun
authors.initials: SH
authors.lastname: Ahn
authors.forename: Eun Sook
authors.initials: ES
authors.lastname: Cho
authors.forename: Won Hyeok
authors.initials: WH
authors.lastname: Choe
authors.forename: Chang Hong
authors.initials: CH
authors.lastname: Lee
authors.forename: Byung Kook
authors.initials: BK
authors.lastname: Kim
authors.forename: Soon Young
authors.initials: SY
authors.lastname: Ko
authors.forename: Hyo Sun
authors.initials: HS
authors.lastname: Choi
authors.forename: Eun-Sook
authors.initials: ES
authors.lastname: Park
authors.forename: Gu Choul
authors.initials: GC
authors.lastname: Shin
authors.forename: Kyun-Hwan
authors.initials: KH
authors.lastname: Kim
mesh_terms: D000328:Adult; D019943:Amino Acid Substitution / Q000235:genetics; D000998:Antiviral Agents / Q000494:pharmacology* / Q000627:therapeutic use*; D001086:Arabinofuranosyluracil / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D004252:DNA Mutational Analysis; D024882:Drug Resistance, Viral; D005260:Female; D006515:Hepatitis B virus / Q000187:drug effects* / Q000302:isolation & purification; D019694:Hepatitis B, Chronic / Q000188:drug therapy / Q000821:virology*; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D020125:Mutation, Missense; D012194:RNA-Directed DNA Polymerase / Q000235:genetics; D017422:Sequence Analysis, DNA; D044967:Serum / Q000821:virology; D017211:Treatment Failure; D014764:Viral Proteins / Q000235:genetics
chemical_list: D000998:Antiviral Agents; D014764:Viral Proteins; D001086:Arabinofuranosyluracil; D012194:RNA-Directed DNA Polymerase; C034935:clevudine