Cytotoxic trNK cells preferentially expand during MCMV infection and contribute to viral control in the SG. (A and B) SG group 1 ILCs shown as (A) ratio between naïve and MCMV infected or (B) absolute counts of measured by flow cytometry. (C and D) Representative plots (C) and quantification (D) of trNK cells subsets during MCMV infection. (E) Immunofluorescence staining of SGs from naïve and MCMV infected Ncr1^CreR26R^Ai14 mice at 16 dpi, showing DAPI (blue), NKp46-TdTomato (magenta), GzmB (yellow), and EpCAM (teal). Scale bars, 50 μm. (F and G) Quantification (F) and representative flow cytometry plots (G) of SG group 1 ILCs of WT and Ncr1^CreTgfb1^fl mice at indicated stages of MCMV infection. (H) Quantification of IFN-γ⁺ group 1 ILCs in the SG at 10 dpi. (I and J) Representative plots (I) and quantification (J) of GzmB⁺ group 1 ILCs in the SG at 16 dpi. (K) Viral M86 gDNA levels in SGs of WT and Ncr1^CreTgfb1^fl mice at 7, 16 and 28 dpi, measured by qPCR. (A–D) Data pooled from two independent experiments with total n = 6 mice per timepoint, or (E) representative for n = 2–4 mice, or (F–J) representative of two to three independent experiments with n = 4–10 mice per group, or (K) pooled from two independent experiments with total n = 7–9 mice per group. Error bars display means ± SD. Statistical significance was calculated using one-way ANOVA or two-tailed t test; *P < 0.05, ***P < 0.001, and ****P < 0.0001. ns, not significant.