B cells are less susceptible to VSV infection than DCs, and virus-pulsed B cells do not directly present the target antigen. (A) Cultured B cells and DCs were infected with VSV-GFP or VSV-MT at an MOI of 25. After 24 hours, GFP expression was determined in combination with surface marker staining for B220 and CD11c. (B) Vac-GP33–primed mice were boosted with WT or K^bD^b−/− B cells loaded with VSV-GP33, or PBS as control. The magnitude of GP33-specific T-cell responses in blood was measured by intracellular cytokine staining 5 days after boosting (n = 5/group, *P < .01 compared with PBS control). (C) Vac-GP33–primed mice were boosted with B/VSV-GP33 or 2 × 10⁶ PFU of VSV-GP33 or PBS as control. Boosted responses in blood were measured 5 days post-secondary vaccination. *Significantly higher CD8⁺ T-cell response compared with VSV alone and PBS control (P < .01). Data are representative of duplicate experiments using 5 mice per group. GFP, green fluorescent protein; PBS, phosphate-buffered saline.