ABSTRACT
A small-molecule inhibitor of hepatitis C virus (HCV) designated AP89652 was identified by screening a compound library with an HCV genotype 1b subgenomic replicon assay. AP89652 contains two chiral centers, and testing of two
syn
enantiomers revealed that activity in the replicon assay resided with only one, AP80978, whose 50% effective concentration (EC
50
) (the concentration at which a 50% reduction in
Renilla
luciferase levels was observed relative to an untreated control) was 630 nM. AP80978 was inhibitory against HCV genotypes 1a and 1b but not genotype 2a. In a replicon clearance assay, the potency and clearance rate of AP80978 were similar to those of telaprevir (VX950) and cyclosporine (CsA). AP80978 was nontoxic when tested against a panel of human cell lines, and inhibitory activity was HCV specific in that there was limited activity against negative-strand viruses, an alphavirus, and flaviviruses. By selection of resistant replicons and assessment of activity in genotype 1b/2a intergenotypic replicons, the viral protein target of this compound was identified as NS4B. NS4B F98V/L substitutions were confirmed by site-directed mutagenesis as AP80978 resistance-associated mutations. When tested against HCV produced in cell culture, the compound was significantly more potent than other HCV inhibitors, including VX950, CsA, and 2′-C-methyladenosine (2′C-meA). In addition, AP80977, the enantiomer that was inactive in the replicon assay, had activity against the virus, although it was lower than the activity of AP80978. These results suggest that AP80978 has the potential to be optimized into an effective antiviral drug and is a useful tool to further study the role of NS4B in HCV replication.
摘要
通过使用 HCV 基因型 1b 亚基因组复制试验筛选化合物库,发现了一种丙型肝炎病毒(HCV)小分子抑制剂 AP89652。AP89652 含有两个手性中心,并测试了两个
对映体
对映体的测试表明,在复制子试验中只有 AP80978 具有活性,其 50%有效浓度(EC
50
)(使雷尼拉苷元的活性降低 50%的浓度)。
荧光素酶
荧光素酶水平降低 50% 的浓度)为 630 nM。AP80978 对 HCV 基因型 1a 和 1b 有抑制作用,但对基因型 2a 没有抑制作用。在复制子清除试验中,AP80978的效力和清除率与替拉瑞韦(VX950)和环孢素(CsA)相似。AP80978 在对一组人类细胞系进行测试时无毒性,其抑制活性具有 HCV 特异性,对负链病毒、一种阿尔法病毒和黄病毒的活性有限。通过筛选耐药复制子和评估基因型 1b/2a 基因型间复制子的活性,确定了该化合物的病毒蛋白靶标为 NS4B。通过定点突变确认了 NS4B F98V/L 突变为 AP80978 的耐药性相关突变。在对细胞培养中产生的 HCV 进行测试时,该化合物的效力明显高于其他 HCV 抑制剂,包括 VX950、CsA 和 2′-C-甲基腺苷(2′C-meA)。此外,在复制子试验中无活性的对映体 AP80977 对病毒也有活性,但低于 AP80978 的活性。这些结果表明,AP80978 有可能被优化为一种有效的抗病毒药物,是进一步研究 NS4B 在 HCV 复制中的作用的有用工具。