title: Mechanism of entecavir resistance of hepatitis B virus with viral breakthrough as determined by long-term clinical assessment and molecular docking simulation.
abstract: The mechanism by which entecavir resistance (ETVr) substitutions of hepatitis B virus (HBV) can induce breakthrough (BT) during ETV therapy is largely unknown. We conducted a cross-sectional study of 49 lamivudine (LVD)-refractory patients and 59 naïve patients with chronic hepatitis B. BT was observed in 26.8% of the LVD-refractory group during weeks 60 to 144 of ETV therapy. A line probe assay revealed ETVr substitutions only in the LVD-refractory group, i.e., in 4.9% of patients at baseline, increasing to 14.6%, 24.4%, and 44.8% at weeks 48, 96, and 144, respectively. Multivariate logistic regression analysis adjusted for age, gender, HBV DNA levels, and LVD resistance (LVDr) (L180M and M204V, but not M204I) indicated that T184 substitutions and S202G (not S202C) were a significant factor for BT (adjusted odds ratio [OR], 141.12, and 95% confidence interval [CI], 6.94 to 2,870.20; OR, 201.25, and 95% CI, 11.22 to 3608.65, respectively). Modeling of HBV reverse transcriptase (RT) by docking simulation indicated that a combination of LVDr and ETVr (T184L or S202G) was characterized by a change in the direction of the D205 residue and steric conflict in the binding pocket of ETV triphosphate (ETV-TP), by significantly longer minimal distances (2.2 A and 2.1 A), and by higher potential energy (-117 and -99.8 Kcal/mol) for ETV-TP compared with the wild type (1.3 A; -178 Kcal/mol) and LVDr substitutions (1.5 A; -141 Kcal/mol). Our data suggest that the low binding affinity of ETV-TP for the HBV RT, involving conformational change of the binding pocket of HBV RT by L180M, M204V plus T184L, and S202G, could induce BT.
authors.affiliation: Department of Virology and Liver Unit, Nagoya City University Graduate School of Medical Sciences, and Department of Gastroenterology, Nagoya Daini Red Cross Hospital, Nagoya 467-8601, Japan.
authors.forename: Motokazu
authors.initials: M
authors.lastname: Mukaide
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Tadasu
authors.initials: T
authors.lastname: Shin-I
authors.forename: Man-Fung
authors.initials: MF
authors.lastname: Yuen
authors.forename: Fuat
authors.initials: F
authors.lastname: Kurbanov
authors.forename: Osamu
authors.initials: O
authors.lastname: Yokosuka
authors.forename: Michio
authors.initials: M
authors.lastname: Sata
authors.forename: Yoshiyasu
authors.initials: Y
authors.lastname: Karino
authors.forename: Gotaro
authors.initials: G
authors.lastname: Yamada
authors.forename: Kohsaku
authors.initials: K
authors.lastname: Sakaguchi
authors.forename: Etsuro
authors.initials: E
authors.lastname: Orito
authors.forename: Manami
authors.initials: M
authors.lastname: Inoue
authors.forename: Sumbella
authors.initials: S
authors.lastname: Baqai
authors.forename: Ching-Lung
authors.initials: CL
authors.lastname: Lai
authors.forename: Masashi
authors.initials: M
authors.lastname: Mizokami
mesh_terms: D000328:Adult; D000998:Antiviral Agents / Q000494:pharmacology* / Q000627:therapeutic use*; D003198:Computer Simulation; D003430:Cross-Sectional Studies; D004279:DNA, Viral / Q000235:genetics; D024882:Drug Resistance, Viral / Q000235:genetics*; D005260:Female; D006147:Guanine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D006509:Hepatitis B / Q000188:drug therapy / Q000821:virology; D006515:Hepatitis B virus / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D006801:Humans; D019259:Lamivudine / Q000494:pharmacology / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009154:Mutation; D016133:Polymerase Chain Reaction; D012194:RNA-Directed DNA Polymerase / Q000235:genetics; D014764:Viral Proteins / Q000235:genetics
chemical_list: D000998:Antiviral Agents; D004279:DNA, Viral; D014764:Viral Proteins; D019259:Lamivudine; C413685:entecavir; D006147:Guanine; D012194:RNA-Directed DNA Polymerase