Figure 5. Anti-tumor efficacy of MvP728-survivin vaccine alone and with GSL1.
(A) Mice were vaccinated with survivin twice with a 2-week interval using one of the indicated strains of attenuated Salmonella. One week after the last vaccination, mice were s/c injected with 2×106 of CT26 cells. (B) Mice were s/c injected with 5 × 105 CT26 cells followed by vaccination with MvP728 with vector control or survivin construct with or without GSL1 at days 3 and 10 after tumor implantation. (C) Mice were s/c injected with 2 × 105 CT26 cells followed by vaccination with MvP728 with GSL1. When indicated, mice received anti-CD8 depleting mAb or rat IgG control. Non-vaccinated mice served as a control. Tumor size was measured every two-three days and plotted as means ± SD (8 mice per group). Experiments in A–C were repeated at least once with similar results. (D) Splenocytes from indicated groups of mice were in vitro stimulated with a survivin peptide library and IL-2 for 7 days followed by isolation of CD8 T cells using magnetic beads and evaluation of their cytotoxicity against Calcein-AM-labeled CT26 cells. (E) In vitro re-stimulated CD8 T cells from the vaccine+GSL1 group of mice were tested in the Calcein-AM cytotoxicity assay against two syngeneic and two allogeneic survivin-expressing tumor cell lines. Data are Mean ± SD from two experiments performed in triplicates.