Fernandes Fiona, Poole Daniel S, Hoover Spencer, Middleton Rannveig, Andrei Adin-Cristian, Gerstner Justin, Striker Rob
Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, USA.
Hepatology. 2007 Oct;46(4):1026-33. doi: 10.1002/hep.21809.
HCV re-occurs after liver transplantation and increases mortality. Cyclosporine, but not tacrolimus, has potent antiviral effects against HCV replication in cell culture. To determine the conditions, if any, under which HCV is susceptible to cyclosporine in vivo, we selected for cyclosporine-resistant mutant HCV in vitro. The resulting mutations were mapped to x-ray crystallographic structures and sequence databases. Mutations selected by cyclosporine were clustered in the nonstructural (NS) proteins NS5A and NS5B. Different sets of mutations in NS5A, paired with the same 2 NS5B mutations, conferred different levels of cyclosporine resistance when engineered back into the HCV replicon. Mutations in NS5B are structurally consistent with a proposed model of regulation of RNA binding by cyclophilin B (CyPB). These mutations also highlight a natural polymorphism between different HCV genotypes that correlates with the variation in response to cyclosporine A (CsA) noted in some clinical trials. Replicons engineered to have mutations in only NS5A (P < or = 0.0001) or only NS5B (P = 0.002) suggest that while both NS5A or NS5B variants alter cyclosporine susceptibility, NS5A has the largest effect.
Preexisting sequence variation could alter the effect of cyclosporine on HCV in vivo.
丙型肝炎病毒（HCV）在肝移植后会复发并增加死亡率。在细胞培养中，环孢素对HCV复制具有强大的抗病毒作用，而他克莫司则没有。为了确定HCV在体内对环孢素敏感的条件（如果存在的话），我们在体外筛选了对环孢素耐药的HCV突变体。将产生的突变映射到X射线晶体学结构和序列数据库中。由环孢素选择的突变聚集在非结构（NS）蛋白NS5A和NS5B中。当重新构建到HCV复制子中时，NS5A中不同的突变集与相同的两个NS5B突变配对，赋予了不同程度的环孢素抗性。NS5B中的突变在结构上与亲环蛋白B（CyPB）调节RNA结合的模型一致。这些突变还突出了不同HCV基因型之间的自然多态性，这与一些临床试验中观察到的对环孢素A（CsA）反应的差异相关。仅在NS5A（P≤0.0001）或仅在NS5B（P = 0.002）中具有突变的复制子表明，虽然NS5A或NSB变体都会改变环孢素的敏感性，但NS5A的影响最大。
预先存在的序列变异可能会改变环孢素在体内对HCV的作用。
