Vaccination with NK-cell targets results in effective protection against OVA-expressing L monocytogenes. C57BL/6 mice were immunized with either 10⁷ irradiated cells or 10⁷ or 10⁶ live act-mOVA.K^b−/− splenocytes. As a positive control, mice were immunized with a low dose (10³) of L monocytogenes. On day 35 after immunization, mice were challenged with 10⁵ CFU of LM-OVA and splenic titers were determined after an additional 3 days (n = 8 for each group). *P ≤ .05; **P ≤ .01 as determined by ANOVA.