Loss of unlicensed NK subset regulation of adaptive immunity with high viral load. (A) NK cell subset depletion and MCMV challenge. (B) Representative flow staining of M45-tetramer on liver CD3⁺CD8⁺ T cells at post-MCMV infection day 7 in control (uninfected) or LD- or HD-infected C57BL/6 mice. Absolute number of M45⁺CD8⁺ tetramer T cells in the liver at day 7 post-LD (C) or -HD (D) MCMV infection. Viral load on postinfection day 7 of LD (E) or HD (F) MCMV after NK-cell subset depletion. Means ± standard error of the mean are shown for 3 or 4 mice per group, representative of 2 experiments. One-way ANOVA with Tukey post hoc test, to compare groups. *P < .05; **P < .01; ***P < .001, by 1-way ANOVA with Tukey post hoc test.