For HDV infections the inhibitors were present from 24 h prior to infection and during the 16 h of exposure to virus. Replication was assayed at 6 days post-infection by realtime PCR, as in Fig. 1C. The assays were performed in triplicate, and average values are expressed as a percentage relative to the untreated controls, with the indicated standard error of the mean. For the VSV infections, the interferon was only present during the 16 h of virus exposure. VSV replication was assayed at 16 h by counting GFP positive cells. The values are expressed relative to untreated controls and the errors indicate the standard deviation as the square root of the mean. Interferon-alpha concentrations are expressed here as molarities, with 600 units/ml = 0.12 nM. The preS1 peptide, like interferon-alpha, can inhibit HDV infection, but the needed molarity is 300-times more. Interferon-alpha can inhibit VSV infection but the concentration is 1,000-time less than that needed to inhibit HDV.