Ad5-Clostridium difficile-TA vaccine induces robust TA-specific T cell responses in contrast to Ad5-Null. WT BALB/c mice were IM injected (1010 vp/mouse) with Ad5-C. difficile-TA (n = 5) or Ad5-Null (n = 5). Mice were sacrificed at 14 dpi splenocytes prepared, and individually stimulated with 0.2 μg/well of single most immunogenic peptides from the TA library (or with inactivated Ad5 vector). IFNγ ELISPOT was performed as described in Section 2. Naïve (n = 3) mice were stimulated with same peptides as baseline control. Bars represent mean ± SD. Statistical analysis was completed using Two-Way ANOVA with a Bonferroni post hoc test (stimulations × treatments), p < 0.05 was deemed a statistically significant difference. *, **Statistically different from those in naïve mice (for the same stimulation), p < 0.05, p < 0.001, respectively; #, ##Significant inductions over Ad5-Null group within the same stimulation, p < 0.05, p < 0.001, respectively. One of two representative experiments shown.