The effect of viral DNA polymerase inhibitors on cell number. Uninfected (BL41 cells; A) and HHV-8-infected (BCBL-1 cells; B) B-cell lymphoma cells were examined for changes in cell number resulting from incubation with ganciclovir (2-200 μM) and PFA (100 or 750 μM) in the absence (▪) and presence (▦) of valproate (0.6 mM). Viable cells were counted by direct visualization of cells that excluded trypan blue by using a hemocytometer on day 3. The number of cells present in the untreated control on day 3 for each cell type was labeled 100%, and the mean number of cells present for each condition was compared with this value. Data shown are mean ± SD from triplicate determinations.