FIG. 4.

Steady-state RNA levels transcribed from the US3 promoter with either the wild-type or mutant CRS downstream of the R₁ silencer or the enhancer-containing MIE promoter at early and late times after infection (h.p.i. [hours postinfection]). HFF cells were infected with approximately 5 PFU of RVgptR₁CAT or RVgptR₁crs⁻CAT per cell. RNA samples were analyzed and designated as described in the legend to Fig. 3. Std, ³²P-labeled DNA standard molecular weight markers, positions of which are indicated in nucleotides.