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.
Antimicrob Agents Chemother. 2010 Feb;54(2):882-9. doi: 10.1128/AAC.01061-09. Epub 2009 Nov 23.
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.
恩替卡韦耐药（ETVr）突变导致乙型肝炎病毒（HBV）在恩替卡韦治疗期间发生突破（BT）的机制在很大程度上尚不清楚。我们对 49 例拉米夫定（LVD）耐药患者和 59 例慢性乙型肝炎初治患者进行了一项横断面研究。在恩替卡韦治疗的第 60 至 144 周期间，LVD 耐药组中有 26.8%观察到 BT。线性探针分析仅在 LVD 耐药组中发现恩替卡韦耐药突变，即基线时 4.9%的患者，分别在第 48、96 和 144 周时增加至 14.6%、24.4%和 44.8%。多变量 logistic 回归分析调整了年龄、性别、HBV DNA 水平和 LVD 耐药（L180M 和 M204V，但不包括 M204I），表明 T184 取代和 S202G（而非 S202C）是 BT 的显著因素（调整后的优势比[OR]分别为 141.12 和 95%置信区间[CI]为 6.94 至 2870.20；OR 为 201.25 和 95%CI 为 11.22 至 3608.65）。通过对接模拟对 HBV 逆转录酶（RT）进行建模表明，LVDr 和 ETVr（T184L 或 S202G）的组合导致 D205 残基的方向发生变化，并且在 ETV 三磷酸（ETV-TP）的结合口袋中存在空间冲突，最小距离明显延长（2.2 A 和 2.1 A），与野生型（1.3 A；-178 Kcal/mol）和 LVDr 取代（1.5 A；-141 Kcal/mol）相比，ETV-TP 的势能更高（-117 和-99.8 Kcal/mol）。我们的数据表明，恩替卡韦三磷酸（ETV-TP）与 HBV RT 的低结合亲和力，涉及 L180M、M204V 加 T184L 和 S202G 导致 HBV RT 结合口袋构象改变，可能导致 BT。
