NK cells and IFNγ in persistently mCMV infected mice contributed to reduced FV titers and enhanced FV-specific CD8 T cell responses. Depletion of NK1.1+ cells and blockage of IFNγ was performed in persistently mCMV infected mice at day −1, 2 and 4 post FV infections. As control naïve (white dots) and persistently mCMV infected (black dots) mice were superinfected with FV. FV loads were detected by an infectious center assay (a) and functional FV-specific CD8 T cells were determined by granzyme B expression gated on tetramer + CD8 T cells (b) at day 8 post FV infection. Data shown are pooled from 2–4 independent experiments. Statistical analysis: one-way ANOVA (Dunett’s multiple comparison test). Statistically significant differences between the groups are indicated by n.s. no significant differences, * p < 0.05, ** for p < 0.001.