IFNG and infection: Indeed, the CTL response in PA28αβ-knockout mice and wild-type mice directed against GP33–41/Db/Kb, NP396–404/Db, GP276–286/Db, GP92–101/Db, GP118–125/Kb and NP205–212/Kb on day 8 post-LCMV-WE infection by intracellular cytokine staining (ICS) for IFN-γ showed a similar strength and hierarchy (Figure 3d).