FIG. 2.

Effect of ICP0 preexpression on sensitivity to IFN pretreatment of HSV-1 plaque formation. HA-TetR and HA-cICP0 cells were treated with tetracycline (0.1 μg/ml) for 24 h (lower panel) or left untreated (upper panel) before subsequent treatment for 24 h with increasing concentrations of IFN-β, as indicated. Plaque assays using in1863 were then conducted on replicate wells under each condition, and the numbers of plaques were counted. The results are expressed as relative inhibition of plaque numbers compared to samples not treated with IFN. The data show means and standard deviations of plaque reduction factors from four or five determinations at each concentration of IFN.