Figure 3.

rP18tri-based TB vaccines induced strong antigen-specific CD8 T cells through both IM and IN routes. (A) BL6 mice (N = 4-5) were immunized with PBS (M), rP18tri vector alone (V), or TBvac-2 through either IM or IN route. Lymphocytes from peripheral blood (PBMC), spleen, and lung were incubated with PE-labeled MHC-I EsxH tetramer, along with antibodies against surface markers (CD3, CD8, and CD44), and analyzed by flow cytometry. Representative flow cytometry plots of the tetramer-positive CD44^hCD8 T cells in peripheral blood (PBMC), spleens, and lungs from vector and TBvac-2-immunized mice are shown (B). The percentage of tetramer-positive CD44^hCD8T cells in PBMCs (C) and spleens (D) is shown for each group (M, V, and TBvac-2) at 7 dpp through IM or IN route. The percentage of tetramer-positive CD44^hCD8T cells in lungs (E) is shown for each group (M, V, and TBvac-2) at 7 days post-boost (dpb) through IM-IM or IN-IN route. A similar study was conducted to evaluate the TBvac-10-induced CD8T cells. BL6 mice (N=5) were immunized with rP18tri vector (V) or TBvac-10 through IM-IN prime-boost strategy. Representative flow cytometry plots (F) and the percentage (G) of tetramer-positive CD44^hCD8T cells at 7 dpb in PBMCs, spleens, and lungs from vector and TBvac-10-immunized mice are shown. Statistical analysis was conducted with unpaired t-test. ***p < 0.001; **p < 0.01; *p < 0.05; ns, not significant.