Galidesivir triphosphate is a substrate for viral RNA-dependent RNA polymerase (RDRP), resulting in termination of viral RNA replication and thus serves as an antiviral. Galidesivir triphosphate inhibits HCV NS5B RNA polymerase activity and protects mice against Ebola. Galidesivir triphosphate (Immucillin-A triphosphate) is converted by the prodrug Galidesivir.