FIG. 3.

The inhibition of HSV DNA synthesis by Rosco added at the time of release from a 12-h PAA block is multiplicity dependent. (A) Vero cells were infected at the indicated multiplicities (MOI) with HSV, washed, and overlaid with medium containing 100 μg of PAA per ml. At 12 h p.i. medium was removed and fresh medium containing no drug (PAA 12 → C 24), 100 μg of PAA per ml (PAA 12 → PAA 24), or 100 μM Rosco (PAA 12 → Ro 24) was added. At 24 h after the change of medium, cells were harvested and the amounts of viral DNA were determined by slot blot analysis. (B) After quantitation of the blots presented in panel A using a Molecular Dynamics PhosphorImager system, the fold increase in viral DNA replication was calculated by dividing the amount of viral DNA detected at 12 h postrelease by the amount detected immediately after infection and subtracting 1, such that a total block in viral DNA replication by the secondary drug would be indicated by 0-fold increase. The fold increase in DNA replication was then plotted against the multiplicity (MOI). The results from one of two repeat experiments are presented.