Acquisition of virus by Mac-1⁺/Gr-1⁺ cells. (A) ICA on total FP leukocytes collected from 10 mice at 48 hours after inoculation with RQ461 or RM461 (inoculum of 1 × 10⁶ PFUs) shown as geometric mean percentage virus-positive FP cells ± standard deviation of the geometric mean (error bars). (B) FCM analysis of mck-expressing RM4503-infected infiltrates prepared from independent groups of 5 BALB/c mice at 72 hours after inoculation (inoculum of 1 × 10⁶ PFUs). Bottom left panel shows the Mac-1 and Gr-1 staining pattern for this population, and the 3 adjacent panels show FCM analysis of GFP in quadrants R2, R3, and R4, as indicated by arrows. A solid line indicates the histogram for RM4503, and a dashed line indicates the histogram for control RQ461-infected cells. (C) FCM analysis of mck-mutant RM4511-infected FP infiltrates prepared from 5 BALB/c mice at 72 hours after inoculation (inoculum of 1 × 10⁶ PFUs). Bottom left panel shows the Mac-1 and Gr-1 staining pattern for this population, and the 3 adjacent panels show FCM analysis for GFP in quadrants R2, R3, and R4. A solid line indicates the histogram for RM4511, and a dashed line indicates the histogram for control RM461-infected cells. The percentage of GFP⁺ cells is indicated above the brackets in each of the panels.