Detection of the lacZ gene sequence in macrophages infected with CMV RC256. Alveolar macrophages, cultured at a density of 1 × 10⁶ cells/well for 7 days, were either pretreated with 50 ng/mL of IL-13 or received growth medium alone for 2 days before infection with HCMV. Cultures were then exposed either to the lacZ recombinant CMV, RC256 (MOI of 1), or growth medium (Mock) for 4 hours, washed 3× with PBS and refed with growth medium supplemented with IL-13 (+) or growth medium alone (−). The growth medium was changed every 3 days. Cells were collected at days 3 and 10 postvirus exposure, and 25 ng of cellular DNA was used as a template for amplification with β-gal primers by PCR under conditions described in Materials and Methods. An equal amount of DNA from the Hela-CD4-LTR β-gal cell line was amplified as a positive control. Amplified DNA was subjected to liquid hybridization with a ³²P-labeled β-gal probe, electrophoresed through 8% polyacrylamide gel electrophoresis, and visualized overnight by autoradiography.