Structurally distinct cyclosporin and sanglifehrin analogs CRV431 and NV556 suppress established HCV infection in humanized-liver mice.

We previously reported that the non-immunosuppressive cyclophilin inhibitors (CypIs)—cyclosporin A analog CRV431 and sanglifehrin analog NV556—efficiently inhibit HCV replication in vitro. In this study, we asked whether they can also reduce HCV replication in vivo. We found that a single oral administration of CRV431 and NV556 to HCV-infected humanized-liver mice drastically reduced HCV blood levels. The antiviral effect was observed when CRV431 or NV556 were each individually administered with HCV, 3, 6 weeks or even 3 months post-infection when viral replication is robust. These results were confirmed in chimeric mice implanted with human hepatocytes isolated from three distinct donors. Remarkably, no viral rebound was observed 5 months after a single dose administration of 50 mg/kg of CRV431 or NV556 four weeks post-HCV infection, indicating the possibility of suppression of an established viral infection. Since we recently demonstrated that both CRV431 and NV556 also inhibit the development of liver fibrosis and hepatocellular carcinoma in nonviral-induced non-alcoholic steatohepatitis mouse models, our present data suggest that the two entirely structurally different CypIs—CRV431 and NV556—derived from unrelated natural products, represent attractive partners to current direct-acting agent (DAA) regimens for the treatment of hepatitis C and liver diseases.