Innate resistance to HSV-1 is not dependent on NK cell cytotoxicity. A. Cytotoxic activity of WBCs from BALB/c, BALB/c scid, or NOD scid mice, as determined by percent maximum 51Cr release achieved when 104 YAC-1 (target) cells were incubated with 250,000 spleen WBCs (n = 3 per group). B. Duration of survival of BALB/c scid mice and NOD scid mice following ocular inoculation with 2 × 105 pfu/eye HSV-1 strain KOS (n = 5 per group). C. NK cell frequency in the spleens of BALB/c, BALB/c scid, or NOD scid mice (n = 2 per group).