FIG. 4.

Effect of deletion mutations on CAT expression from the UL4-CAT promoter in infected HFFs. HFFs were infected with recombinant viruses at 5 PFU/cell in quadruplicate as described in the legend to Fig 3. The infection was performed in parallel with that of the RNase protection assay as described in Fig. 3. Equal MOI was confirmed by RNase protection assay of protected IE1 mRNA. The CAT activity per microgram of protein was normalized to IE1 mRNA for each recombinant virus at different time points after infection as described in Materials and Methods. The results of the CAT assays were averaged, and the standard deviations were calculated.