FIG. 4.

NS-398 suppression of MHV-68 viral protein expression is relieved in the presence of exogenous PGE₂. NIH 3T3 cells were untreated (lanes 1 and 2) or pretreated with DMSO (lane 3) or 5 (lanes 4 and 6) or 0.5 (lanes 5 and 7) μM NS-398. Cells were infected with wt MHV-68 (lanes 2 to 7) and maintained in the appropriate DMSO-NS-398 concentrations. Subsequently, infected cells treated with NS-398 were also treated with 1 μM PGE₂ (lanes 6 and 7), and cell extracts were harvested at 12 h postinfection for Western blot analysis using an antibody to a late lytic gene product, MHV-68 M9-ORF 65 (upper panel). Control cells were uninfected (lane 1) or infected with no treatment (lane 2). As a loading control, the blot was probed with antiactin (lower panel). Each lane contains 15 μg of total protein as determined by Bradford assays.