BALB/c mice were immunized with 10 μg pVax-HA, 10 μg pVax-NP, and 10 μg adjuvant DNA (or pVax-empty as control) via intramuscular injection followed by electroporation. Two weeks after the immunization, a subset of animals was euthanized to analyse the CD8+ T cell responses in the spleen. (A-B) Splenocytes were restimulated with the immunodominant MHC I restricted peptides from NP (NP147-155; A) or HA (HA518-526; B) and antigen-specific CD8+ T cells were identified by their secretion of IFN-γ, IL-2, and TNF-α as well as by the staining of CD107+ as degranulation marker. The left graphs depict mono- and polyfunctional populations, while the right graphs show the sum of responsive antigen-specific T cells positive for at least one of the functional marker. Mean values with standard error of the mean (SEM) represent data from four mice per group. #, p < 0.05 vs. naive; *, p < 0.05 vs. pVax-empty (Kruskal-Wallis non-parametric one-way ANOVA followed by Dunn's post-test).