Figure 4.

rP18tri-based TB vaccines induced strong antigen-specific CD4 T cells. (A) BL6 mice (N=5) were immunized with rP18tri vector (V), TBvac-2, and TBvac-10 through IM-IN or IN-IN prime-boost strategy. At 7 dpb, lymphocytes isolated from spleens or lungs were incubated with a PE-labeled control or Ag85B MHC-II tetramer, together with antibodies against cell surface markers (CD3, CD4, CD8, CD44, CD69). (B) Gating strategy used to analyze the MHC-II tetramer-positive CD44^high (CD44^h) CD4⁺ T cells and lung CD69⁺CD44^hCD4⁺ T cells. (C) Representative flow cytometry plots of control- and Ag85b-tetramer-positive CD44^hCD4⁺ T cells were shown for splenocytes of vector and TBvac-2 immunization, and for lung lymphocytes in vector and TBvac-10 immunization. After normalization with the control MHC-II tetramer, the Ag85B tetramer-positive spleen CD44^hCD4⁺ T cells (D), lung CD44^hCD4⁺ T cells (E), and lung CD69⁺CD44^hCD4⁺ T cells (F) was shown for vector (V), TBvac-2, and TBvac-10 immunization. Statistical analysis was conducted with unpaired t-test. ****p < 0.0001; **p < 0.01; *p < 0.05; ns, not significant.