GZMK and infection: Performing differential gene expression analysis between the cells of cluster 1 separated by infection type demonstrated that T cells isolated from MCMV-ie2-gp33 had significantly increased expression of granzymes (Gzmk, Gzma), activation genes (Ccl5, Nkg7, Klrg1), and MHC class I genes (Supplementary Figure S6 and Supplementary Tables S7, S8), even though the cells occupied the same cluster (Figure 1F).