FIG. 1.

Addition of Roscovitine beginning at 24 h p.i. causes a reduction in HCMV titer and a modest inhibition of viral DNA replication. Human fibroblasts were infected at an MOI of 5 with HCMV Towne. At 24 h p.i., infected cells were treated with 20 μM Roscovitine or DMSO as vehicle control. Growth medium was changed every 24 h as the drug was replenished. (A) Tissue culture supernatants were collected every 24 h beginning at 96 h p.i. through 144 h p.i. Viral titer was determined by standard plaque assay. The results from four independent experiments (Expt. I to Expt. IV) are shown. The bars represent the average log titers for each time point. (B) At the time points indicated, infected cells were collected and pellets were frozen. Viral DNA was extracted as described in Materials and Methods and used as a template for real-time PCR to quantify the level of viral DNA replication. The bars represent the average differences (n-fold) from two independent experiments. In each data set, the level of viral DNA at 24 h p.i. was set at 1 and the increase was calculated relative to the value at 24 h p.i. The error bars indicate ranges of the values from the two experiments.