Figure 1. Viral FcγRs bind Fcγ on the cell surface and opsonizing IgG dependent FcγR activation is restricted to the late phase of HCMV but not HSV replication.

(A) MRC-5 cells were infected with 2 PFU/cell for 72 hpi with HCMV HB5 wildtype, HB5Δgp68, HB5ΔIRLΔgp34 or HB5ΔIRLΔgp68/Δgp34 (left) or 24 hpi with HSV-1 (right). Cells were resuspended with PBS/2% (vol/vol) FCS containing 2 mM EDTA, stained with hFcγ-FITC and measured in a FACS Canto II. Dead cells were excluded by PI or DAPI-staining. (B) MRC-5 cells were infected with 2–3 PFU/cell of HCMV HB5 wt or (C) HSV-1 strain F. After centrifugation enhancement of infection, cells were incubated 3 h at 37°C at 5% CO₂. After washing once, PAA (250 µg/ml) in D-MEM 10% (vol/vol) FCS was added. 48 hpi for HSV or 72 hpi for HCMV, cells were opsonized with grading dilutions of Cytotect for 30 minutes, washed twice with D-MEM 10% (vol/vol) FCS and co-cultivated with 1×10⁵ BW:FcγR-ζ reporter cells per well. Measurement of mIL-2 in supernatants after 16 h of co-cultivation of reporter cells with targets was performed by ELISA. Values are presented in the graphic as OD 450 nm. 3 independent wells were measured, means are shown with standard deviations (error bars) for 2 independent experiments. Significance of results (Student's t-test) is presented in Table S1 as *: p<0.05 **: p<0.01 ***: p<0.001.