(A) The indicated MEF cell lines were infected with 0.1 pfu/cell MHV-68 and cultured for 72 hours, after which they were visualized with light microscope. (B) Cells were treated as in A, then floating and adherent cells were harvested and PI stained for viability by flow cytometry. Data represent at least three experiments, with error bars illustrating standard error, and significance (<0.001 indicated with an asterisk [*]) was calculated using a one-way ANOVA. (C) Supernatants from cells treated as in A were serially diluted and plated on 3T12 cells for quantitation by plaque assay. Three wells were counted from the 1:32,000 dilution of supernatant in each of two experiments.