Characterization of the Anti-Hepatitis C Virus Activity of New Nonpeptidic Small-Molecule Cyclophilin Inhibitors with the Potential for Broad Anti-Flaviviridae Activity

摘要

Although members of the Flaviviridae display high incidence, morbidity, and mortality rates, the development of specific antiviral drugs for each virus is unlikely. Cyclophilins, a family of host peptidyl-prolyl cis-trans isomerases (PPlases), play a pivotal role in the life cycles of many viruses and therefore represent an attractive target for broad-spectrum antiviral development. We report here the pangenotypic anti-hepatitis C virus (HCV) activity of a small-molecule cyclophilin inhibitor (SMCypl). Mechanistic and modeling studies revealed that the SMCypl bound to cyclophilin A in competition with cyclosporine (CsA), inhibited its PPlase activity, and disrupted the CypA-nonstructural protein 5A (NSSA) interaction. Resistance selection showed that the lead SMCypl hardly selected amino acid substitutions conferring low-level or no resistance in vitro. Interestingly, the SMCypl selected D320E and Y321H substitutions, located in domain II of the NS5A protein. These substitutions were previously associated with low-level resistance to cyclophilin inhibitors such as alisporivir. Finally, the SMCypl inhibited the replication of other members of the Flaviviridae family with higher 50% effective concentrations (EC(50)s) than for HCV. Thus, because of its chemical plasticity and simplicity of synthesis, our new family of SMCypls represents a promising new class of drugs with the potential for broad-spectrum anti-Flaviviridae activity as well as an invaluable tool to explore the role of cyclophilins in viral life cycles.