Fu L, Liu S H, Cheng Y C
Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA.
Biochem Pharmacol. 1999 Jun 15;57(12):1351-9. doi: 10.1016/s0006-2952(99)00073-8.
L-(-)2',3'-Dideoxythiacytidine (L(-)SddC, Lamivudine) resistant hepatitis B virus (HBV) develops in patients after prolonged treatment. Point mutations detected in the viral genome from these patients have been shown to be responsible for L(-)SddC resistance. Therefore, new drugs active against L(-)SddC resistant HBV are needed. Using a transient transfection system, we studied the sensitivity of L(-)SddC resistant HBV to other anti-HBV nucleoside analogues. It was found that the L526M mutation alone caused greater resistance to penciclovir (PCV) than did the V553I mutation alone. Both mutations also caused the virus to be less sensitive to L(-)SddC and 2'-fluoro-5-methyl-beta-L-arabinofuranosyluracil (L-FMAU), although the degree of resistance was much less than that to PCV. The A546V mutation had no impact on the sensitivity to L(-)SddC, L-FMAU, and PCV. When these single mutations were coupled with the M550V/I mutation, all the double mutants were resistant to those drugs. Although 2',3'-dideoxy-2',3'-didehydro-beta-L(-)-5-fluorocytidine (L(-)Fd4C) was also less active, the IC50 of L(-)Fd4C against the L(-)SddC resistant mutant was at least fifty times lower than that against cell growth in culture. DNA polymerase associated with L(-)SddC resistant virions was also found to be less sensitive than that with wild-type HBV to those L-nucleoside triphosphates. All the L(-)SddC resistant mutants were still sensitive to 9-(2-phosphonylmethoxyethyl)-adenine (PMEA). These results suggest that different mutations in the HBV genome have a different impact on its sensitivity to those compounds, and L(-)SddC resistant HBV may also be resistant to PCV, L-FMAU, and L(-)Fd4C. A nucleoside analogue less toxic than PMEA could be developed against L(-)SddC resistant HBV.
长期治疗后，患者体内会产生对L-(-)2',3'-二脱氧硫代胞苷（L(-)SddC，拉米夫定）耐药的乙型肝炎病毒（HBV）。在这些患者病毒基因组中检测到的点突变已被证明与L(-)SddC耐药有关。因此，需要研发对L(-)SddC耐药HBV有效的新药。利用瞬时转染系统，我们研究了L(-)SddC耐药HBV对其他抗HBV核苷类似物的敏感性。结果发现，单独的L526M突变比单独的V553I突变对喷昔洛韦（PCV）产生的耐药性更强。这两种突变也使病毒对L(-)SddC和2'-氟-5-甲基-β-L-阿拉伯呋喃糖基尿嘧啶（L-FMAU）的敏感性降低，尽管耐药程度远低于对PCV的耐药程度。A546V突变对L(-)SddC、L-FMAU和PCV的敏感性没有影响。当这些单突变与M550V/I突变结合时，所有双突变体对这些药物均耐药。尽管2',3'-二脱氧-2',3'-二脱氢-β-L(-)-5-氟胞苷（L(-)Fd4C）的活性也较低，但其对L(-)SddC耐药突变体的半数抑制浓度（IC50）比对培养细胞生长的IC50至少低50倍。还发现，与野生型HBV相比，与L(-)SddC耐药病毒粒子相关的DNA聚合酶对那些L-核苷三磷酸的敏感性也较低。所有L(-)SddC耐药突变体对9-(2-膦酰甲氧基乙基)-腺嘌呤（PMEA）仍敏感。这些结果表明，HBV基因组中的不同突变对其对这些化合物的敏感性有不同影响，L(-)SddC耐药HBV可能也对PCV、L-FMAU和L(-)Fd4C耐药。可以研发一种毒性低于PMEA的核苷类似物来对抗L(-)SddC耐药HBV。
