FIG. 5.

Transactivating activity induced by wild-type (WT) and Phos mutant forms of ICP0. (A) Vero cells were plated and 24 h later cotransfected with 1 μg of pIE3-CAT reporter plasmid (ICP4 promoter-CAT construct) (18) or with increasing amounts of inducer plasmids (0.375, 0.75, 1.5, and 3 μg) expressing wild-type ICP0 (ICP0), Phos 1, 2, and 3, or the cloning vector alone (pAlter-1). Forty-eight hours after transfection, cells were harvested, extracts were prepared, and CAT assays were performed. The induction (fold) of CAT activity relative to the basal CAT activity of the pIE3-CAT reporter plasmid transfected alone, given the arbitrary value of 1 (bar on the far left), is shown. (B) Transactivating activity of Phos mutants relative to wild-type ICP0 as a function of the amount of inducer DNA transfected. The relative level of transactivation of each Phos mutant was determined by dividing the CAT activity for a given amount of expression plasmid transfected over the CAT activity of an equivalent of amount of wild-type ICP0-expressing plasmid transfected, based on the data presented in panel A. In all cases, wild-type ICP0 was given the arbitrary value of 1 for each amount of wild-type ICP0-expressing plasmid transfected.