Latent infection with MuHV-4 arms NK cells with GzmB protein. Mice were inoculated with media (mock), MuHV-4, or latency-defective MuHV-4 (O73.stop) 31 days before flow cytometric analysis of GzmB expression in NK1.1⁺CD3⁻ NK cells from the spleen and peritoneal cavity. (A) Representative density plots demonstrating GzmB expression within NK1.1⁺CD3⁻ NK cells. (B) Pooled data (10 mice per condition) showing the mean ± SD percentage of NK cells that express GzmB protein. These data are representative of 4 independent experiments, *P < .009 (MuHV-4 vs O73.stop or mock).