(b) Direct Antiviral Effect of CsA

CsA may have a direct antiviral effect, in which Cyps might play a critical role in replication of coronaviruses [11]. Although in vitro data do not necessarily imply effects in vivo, there are numerous in vitro data suggesting antiviral properties of CsA in other non-coronaviral diseases. Through blocking the interaction of cellular cyclophilins with viral proteins and inhibiting viral RNA synthesis, it inhibits replication in hepatitis B virus, hepatitis C virus (HCV), HIV virus, influenza A virus, West Nile virus, Rift Valley fever virus, and Zika virus [50]. In HCV, clinical trials have shown that even non-immunosuppressive derivatives of CsA still can potently suppress HCV viral load in patients [51,52].
