Effect of NK cell versus WBC depletion on innate resistance to HSV-1. BALB/c scid mice, inoculated with 2 × 105 pfu/eye HSV-1 strain KOS-GFP, received i.p. injections of PBS, control IgG or anti-asialo GM1 (1.7 mg) on days -1, 2, 5 and 9 p.i. Cyclophosphamide (CyP; 125 mg/kg) was administered on days -1, 1, and 3 p.i. A. Eyes of KOS-GFP-infected scid mice on day 6 p.i (2× magnification, illuminated with 360–400 nm light which excites GFP fluorescence). One representative image was chosen per group. B. Duration of survival of HSV-1 infected scid mice treated with PBS or CyP (n = 7 each) or control IgG or anti-asialo GM1 (n = 5 each), as compared to uninfected, CyP-treated scid mice (n = 7). Control IgG and anti-asialo GM1 treatment groups initially contained n = 7 mice, but two mice per group were sacrificed on day 5 p.i. for flow cytometry to determine the efficacy of NK cell depletion.