Fig 3.

Twelve months of antiviral treatment leads to profound suppression of the MCMV-specific CD8⁺ T-cell response in aged mice. (A) Mice were infected with MCMV strain Smith (1 × 10⁶ PFU) at 6 to 8 weeks of age. Six months after MCMV infection, the groups remained untreated (MCMV−AV) (n = 9) or treated with valaciclovir (MCMV+AV) (n = 11) for 12 months. In addition, an uninfected age-matched control group was included (MCMV-neg) (n = 5). (B) Frequencies of IFN-γ-positive MCMV-specific CD8⁺ T cells against individual MCMV peptides at 18 months of age from the spleen samples of MCMV−AV (n = 9) and MCMV+AV (n = 11) mice. (C) The magnitude of the total MCMV-specific T-cell immune response is shown as the sum of the five immunodominant IFN-γ-specific CD8⁺ T-cell responses (data in panels A and B were combined from two independent experiments) (mean ± SEM). The data were analyzed by the two-way Mann-Whitney U test (not significant [ns], P > 0.05; *, P < 0.05; **, P < 0.01; and ***, P < 0.001). (D) The rate of decline in the CD8⁺ T-cell immune response against each MCMV peptide following 3, 6, and 12 months of antiviral treatment. The relative changes to the MCMV immune response between untreated and treated MCMV infection are shown; the data from a single experiment are shown; the numbers of mice range from 3 to 4 per time point.