IFNAR signaling is required for MVA-induced NK cell activation. WT or IFNAR^−/− mice were injected in the footpad with 5 × 10⁶ pfu of MVA or with PBS. After 16 hours, NK cells in the draining lymph node were analyzed for CD69 and for intracellular granzyme B and IFN-γ. (A) Representative FACS profiles showing granzyme B, CD69, and IFN-γ staining in NK cells. Data are gated on NK1.1⁺CD3⁻ cells. (B) The percentages of granzyme B^high, CD69⁺ and IFN-γ⁺ NK cells (NK1.1⁺CD3⁻ cells) are compiled for WT and IFNAR^−/− recipients treated or not with MVA. Each dot represents an individual mouse. Data are compiled from 2 to 3 independent experiments (***P < .001).