Specifically, following 5e4 PFU infection, PEP-null and PEP-R619W mature splenic NK cells had less CD107a, a marker of degranulation (Fig. S5A and S5B), increased perforin (Fig. S5C and S5D), and no detectable difference in IFNγ (Fig. S5E and S5F) compared to PEP-WT mature splenic NK cells. The gene discussed is PRF1; the disease is infection.