In mice vaccinated with PAV3-HA, 13,59862066, 14,4426 2541, 69546392, or 20566633 spot-forming cells (sfc) per million splenocytes were detected at days 8, 10, 14, or 21 respectively (Figure 3a) . Immunization with the AdHu5-HA vaccine generated 1,9656341, 12,85861749, 7332693, and 19026372 sfc/million, respectively. The number of sfc/million splenocytes detected at day 8 was statistically significant between PAV3-HA and AdHu5-HA vaccines (p,0.005). The H05-HA immunodominant epitope also stimulated the strongest T-cell responses on day 8 for the PAV3-HA vaccine compared to AdHu5-HA. PAV3-HA vaccinated mice generated an average of 8126138 sfc/million at day 8 whereas 2206133 sfc/million were detected from AdHu5-HA mice at the same time point (Figure 3b , p = 0.048). At day 10, average responses following stimulation with the H05-HA immunodominant epitope were 1,2166178 or 1,364636 sfc/ million from PAV3-HA or AdHu5-HA immunized mice respectively (p = 0.258). T-cell responses of 770674 and 453684 were detected from PAV3-HA or 791658 and 590684 from AdHu5-HA at days 14 and 21 post-immunization, respectively. Restimulation of splenocytes from PAV3-HA or AdHu5-HA immunized mice by the NP control peptide repeatedly generated less than 65 sfc/million. Cellular responses following vaccination with PAV3-HA were further characterized by detecting the relative frequency of peptide-specific CD8 + T cells expressing IFN-c by flow cytometry. Splenocytes were harvested ten days post-immunization and restimulated in vitro with the H05-HA immunodominant peptide and unrelated NP or ZGP (TELRTFSI, Zaire Ebolavirus glycoprotein) control peptides. Cells were stained with anti-mouse CD8-FITC (fluorescein isothiocyanate) and an anti-mouse IFNc-PE (phycoerythrin). The frequency of IFNc positive CD8 + T-cells was 3.460.3 and 2.860.3 percent for PAV3-HA or AdHu5-HA, respectively (Figure 3c ). Cells stimulated with control peptide NP or ZGP showed frequencies of CD8 + IFNc positive T-cells equal to 0.360.05 or 0.660.05 percent, respectively. These results suggest that the PAV3-based vaccine can stimulate a robust immune response in mice faster than AdHu5HA and comparable in strength.