FIG. 4.

Evidence for the cleavage of mature cytoplasmic 28S rRNA in MHV-infected DBT cells. DBT cells at a low confluency were labeled with [³H]uridine for 16 h and then chased, in a medium lacking isotope, for 13 h. Cells were then mock infected (M) or infected with MHV-A59 (I) at an MOI of 10. After adsorption for 1 h, cells were incubated in the presence of actinomycin D (5 μg/ml), and cytoplasmic RNA was extracted at 8 h p.i. Cytoplasmic RNAs were electrophoresed on a 1% denaturing gel. The gel was washed and enhanced prior to autoradiography. The gel was exposed at −80°C for 60 days. The arrows indicate intact 28S rRNA, 28S-CL1, and 18S rRNA.