mCMV persistence resulted in significantly decreased viral loads after FV superinfection. Naïve or persistently mCMV infected mice (day 35 post mCMV infection) were infected with FV. At day 10 post FV infection a) FV titers and b,c) FV-specific target cells (Ter119+ erythrocyte precursor cells, CD19+ B220+ B cells) were determined in spleens. Statistical analysis a) unpaired student t-test, data pooled from 6 independent experiments, b) one-way ANOVA non-parametic Kruskal-Wallis test, data pooled from 3–4 independent experiments with 4–19 mice per group, c) one-way ANOVA Bonferroni’s multiple comparison test, data pooled from 2 independent experiments with 9 mice per group. Statistically significant differences between the groups are indicated by n.s. no significant differences, * p < 0.05, ** for p < 0.001.