Figure 6. B/D vaccination confers enhanced protection against M. tuberculosis challenge in mice and induces heightened multifunctional CD4 T cell response.

The figure depicts (A) the bacillary load in lungs and spleen of mice (n = 4) at 4 weeks post-infection and (B–C) multifunctional T cell response at 12 weeks post-immunization. Mice experiment was performed once. (A) Log₁₀ CFU is represented by box plot (notations are described in the legend of Fig. 1). The lower limit of detection was 1.0 log₁₀ CFU/g of tissue and animals with undetectable bacilli were allotted a CFU value of 1.0 log₁₀/g. *, p<0.05, **, p<0.01 and ***, p<0.001. (One-way ANOVA). (B–C) T lymphocytes were purified from PPD and α-crystallin stimulated splenocytes (pooled from four mice per group) and stained for CD4 T cell surface marker along with intracellular cytokine staining for IFNγ, TNFα and IL2 followed by FACS analysis. (B) Represents frequency (%) of PPD and α-crystallin specific CD4 T cells expressing each of the seven combinations of IFNγ, TNFα and IL2. (C) Represents frequency of PPD and α-crystallin specific 3⁺ CD4 T cells along with MFI and iMFI for IFNγ, TNFα and IL2. B/D: BCG prime – DNAacr boost regimen.