FIG. 1.

Progression of permissive U373 cells into the S phase and inhibition of cell division after HCMV infection. (A) Cell cycle analysis of recombinant virus RΔ-582/-1108gfp-infected U373 cells. U373 cells, serum starved for 48 h, were mock infected or infected with 5 PFU of recombinant virus/cell. The cells were maintained in low-serum medium for an additional 24 h and then in high-serum medium for 48 h. Mock-infected U373 cells were sorted by forward and side scatter. Infected U373 cells were sorted by fluorescence. After propidium iodide (PI) staining, the DNA content of an equal number of cells was determined using a FACS scanner. The PI profile is shown as the solid histogram line. The PI histogram cell cycle analysis was determined by use of the ModFit program as described in Materials and Methods. The quantitation of cell cycle phases is given as percent G₀/G₁/percent S/percent G₂/M. (B) Colony-forming assay using mock-infected or RΔ-582/-1108gfp-infected U373 cells. The sorted cells (20,000) were replated in high-serum medium, incubated at 37°C for 6 days, fixed with formalin, and stained with methylene blue as described in Materials and Methods. A result representative of several experiments is shown.