The degree of STG-175 antiviral efficacy was HCV > HIV-1 > HBV. The addition of STG-175 together with virus totally blocked HCV and HIV-1 infection and greatly attenuated HBV infection. When added 3 days post-infection and then every 3 days, STG-175 totally eradicated the pre-established HCV infection, almost totally aborted the established HIV-1 infection and prevented the viral expansion of the pre-established HBV infection.