FIG. 2.

Steady-state levels of R1 and R2 mRNA during the course of MCMV infection. (A) NIH 3T3 cells were growth arrested in 0.5% calf serum for 48 h and then infected with MCMV (MOI, 5 PFU/cell) or mock infected. Total RNA was isolated at the indicated times after infection and analyzed by Northern blotting. The filter was sequentially hybridized with cellular R1 and R2 and G3PDH radiolabeled probes. (B) The hybridization signals were quantitated with the Bio-Rad image analysis system. The increase in the R1 or R2 mRNA content was calculated by normalizing the amount of radioactivity corresponding to R1 or R2 mRNA to that of G3PDH mRNA (internal control) to correct for differences in RNA loading and recovery. The value at each time point was then normalized to the that observed with mock-infected cells, which was set at 1.