FIGURE 1.

IL-18 is required for efficient NK cell activation and VV clearance. WT and IL-18R^−/− C57BL/6 mice were infected by i.p. injection of 5 × 10⁶ pfu VV or left uninfected (naïve). (A) 24 h after infection, splenocytes were assayed for IFN-γ and GRB production. Representative FACS plots showing the percentage of IFN-γ and GRB-positive NKp46⁺CD3-NK cells are shown. (B) The mean percentages ±s.e.m. of IFN-γ and GRB-positive NK cells (n=3 mice per group) are shown. Interaction term for two-way ANOVA is p<0.01 for IFN-γ and GRB. Data is representative of three independent experiments. (C) 48 h after infection, splenocytes were enriched for DX5⁺ cells and NK cell lytic activity was assayed on YAC-1 target cells by a standard 4-hour chromium release assay at different effector:target ratios. The mean percentages ±s.e.m. of specific lysis are indicated (n=3 per group). ANCOVA comparing infected WT and IL-18R^−/− mice shows p<0.05. Data is representative of two independent experiments. (D) 48 h after infection, ovaries of female mice were harvested for measurement of viral load by plaque assay using TK-143B cells. Data represents the mean viral titer ±s.e.m. as pfu per ovary (n=4 per group). Data is representative of two independent experiments. ** signifies a p-value <0.01 on an unpaired student’s t test.