FIG. 4.

Applications of the reporter cell assay. (A) MeWo cells (7 × 10⁴ cells/well) in 96-well plates were inoculated with cell-associated VZV (∼1 × 10³ MeWo cells infected with VZV; cytopathic effect > 70%) (○, “cell-associated”) or with 250 PFU of cell-free VZV (•, “cell-free”) and cultured in the presence or absence of the indicated concentrations of ACV. Two days later, MV9G cells (7 × 10⁴ cells/well) were added to each well and cocultured in the presence of ACV for 1 day. The cells were harvested, and their luciferase activities were measured. Means and SDs of luciferase activities from triplicate wells are shown. (B) MeWo cells (7 × 10⁴ cells/well) in 96-well plates were inoculated with approximately 200 of MeWo cells infected with TK-positive (pOka [•] and CaQu [⧫]) or -negative (rOkaYSR [○] and Kanno [Δ]) strains (22, 23, 28), and cultured in the presence of ACV for 2 days. Then, MV9G cells were overlaid and cocultured for 1 day. The luciferase activities in the ACV-treated cultures were expressed as percent RLU, with the activities obtained in the culture without inhibitor treatment used as a standard. Means and SDs of luciferase activities from triplicate wells are shown. (C) MeWo cells (7 × 10⁴ cells/well) were infected with cell-associated VZV, cultured for 2 days, and then cocultured with MV9G for 1 day (•, “coculture”). MV9G cells (7 × 10⁴ cells/well) were directly infected with 400 PFU of cell-free VZV, and cultured for 2 days (○, “direct infection”). Roscovitine was added at the indicated concentrations throughout the processes. Means and SDs of luciferase activities from triplicate wells are shown.