FIG. 4.

The enhanced plating efficiency of an ICP0⁻ virus following Gln deprivation is not due to reduced cell density. Vero cells were seeded at initial densities of 5 × 10³ to 1 × 10⁶ cells/35-mm plate. Twenty-four hours later, the monolayers were infected with 100 PFU/plate of wild-type (KOS) or ICP0⁻ (n212) virus in complete DMEM. After a 1-h infection, monolayers were overlaid with complete DMEM containing methyl cellulose. Plaques were counted after a 5-day incubation at 37°C. Plaques did not form in monolayers seeded with 2.5 × 10⁴ or fewer cells. Data points represent the average numbers of PFU/plate in three independent experiments, and error bars represent the standard deviations.