Enumeration of CD8⁺ T-cell antiviral responses to both PyV.WT and PyV.OVA-II. Intracellular cytokine staining was performed on splenocytes 7 to 10 weeks after infection with either wild-type PyV.WT or PyV.OVA-II; uninfected controls were also analyzed. Splenocytes were restimulated with and without a dominant MHC class I–restricted PyV peptide (LT_359-368) and stained with anti-IFNγ. Representative flow plots are shown (A), and compiled data are presented from a representative experiment (B). This experiment has been repeated 3 times (3-5 mice/group per experiment). In all cases, CD8⁺ T cells from infected mice expressed IFNγ upon peptide stimulation. In 2 of 3 experiments, a greater percentage of IFNγ-producing CD8⁺T cells was seen in PyV.OVA-II–infected mice compared with PyV.WT-infected mice; the data shown are from a representative experiment displaying this difference.