FIG. 5.

73.Stop-induced cell death, p53 phosphorylation, and dysregulated early gene expression occur independently of viral replication. (A to C) NIH 3T3 fibroblasts were mock infected, infected with 73.Stop or 73.MR virus at MOIs of 2 to 20 PFU/cell in the presence of 20 ng/ml cidofovir (A and B), or infected with 50.Stop virus at MOIs of 2 to 20 PFU/cell (C). (A) Representative images of cells that were fixed and stained with crystal violet 24 h after infection for imaging by light microscopy. (B) Cell viability determined by trypan blue exclusion 26 h after infection. A minimum of 200 cells per sample was counted. Results are the means from triplicate samples. Error bars represent standard deviations. (C) NIH 3T3 fibroblasts were mock infected or were infected with 73.Stop or 73.MR virus in the presence or absence of 20 ng/ml cidofovir at an MOI of 2 PFU/cell. Equivalent numbers of cells were harvested directly by addition of Laemmli sample buffer 6 h postinfection. Total cell lysates were resolved by SDS-PAGE and were analyzed by immunoblotting with antibodies to the indicated proteins. UV-exposed cells (100 J/m²) serve as a positive control for p53 activation. The blot shown is representative of three independent experiments.