FIG. 4.

Kinetic study of MHV RNA synthesis. MHV-A59-infected 17CL-1 cells were permeabilized and subjected to BrUTP labeling at 4, 5, and 6 h postinfection in the presence of 5 μg of actinomycin D per ml. Actinomycin D was added 1 h before BrUTP labeling. The cells were then double stained with the D₃ antiserum and mouse monoclonal BrdU antibody (RNA) as described in the Materials and Methods.