The ability of B cells to boost secondary T-cell responses is not limited by viral vectors or target antigens. C57BL/6 mice were primed with Vac-SIIN (A) or Ad-GP33 (B). Fourteen days later, mice were boosted with B/VSV-SIIN or B/VSV-GP33, respectively. The frequency of antigen-specific T cells in blood was determined by intracellular cytokine staining 5 days after boosting. (C) C57BL/6 mice were primed with VSV-GP33 and boosted with B cells pulsed with Vac-GP33 (B/Vac-GP33) 14 days after priming. GP33-specific T-cell responses were measured 5 days post-boost. *Significantly higher CD8⁺ T-cell response compared with the unboosted group (n = 5/group, P < .01). IFN, interferon.