Ribavirin and interferon-β synergistically inhibit SARS-associated coronavirus replication in animal and human cell lines

Initial in vitro investigations demonstrated type I interferons (IFNs: IFN-α, IFN-β) to inhibit replication of SARS coronavirus (SARS-CoV), but found the nucleoside analogue ribavirin ineffective in Vero cells. In this report, ribavirin was shown to inhibit SARS-CoV replication in five different cell types of animal or human origin at therapeutically achievable concentrations. Since clinical anti-SARS-CoV activity of type I interferons or ribavirin is limited, we investigated the combination of IFN-β and ribavirin. Determination of the virus yield indicated highly synergistic anti-SARS-CoV action of the combination suggesting the consideration of ribavirin plus IFN-β for the treatment of SARS.