mCMV persistence resulted in an augmented FV-specific CD8 T cell response. a) Absolute numbers of FV-specific CD8 T cells were determined at day 8 and 10 by tetramer staining in spleens of FV infected naïve and persistently mCMV infected mice. Data are pooled from at least 2 (day 10) and 4 (day 8) independent experiments with 7–14 mice per group. b) Absolute numbers of granzyme B+ FV-specific CD8 T cells were determined at day 8 post FV infection in spleens of naïve (white bar) and persistently mCMV infected (black bar) mice. Data shown are 1 representative experiment out of 4 with 4 mice per group. c) In vivo cytotoxicity assay was performed as described in the material and methods section. Data shown are from spleens of 2 independent experiments with 7–8 mice per group. Statistical analysis: unpaired t-test. Statistically significant differences between the groups are indicated by * p < 0.05, ** for p < 0.001.