The protective efficacy and correlation of protection with infection driven immune response in the vaccinated and challenged mice.

<p>(A and B) Protection in vaccinated mice (expressed as Log₁₀ CFU reduction) compared to unvaccinated and BCG vaccinated controls challenged by the aerosol route with virulent <i>M.tb.</i> six weeks after the final vaccination. Six weeks post-challenge, the mice were sacrificed and the bacterial burden (CFU) was measured in the lung or spleen. Data represent the mean+SEM of a minimum of five mice per group in two individual experiments with ***, p<0.001 and **, p<0.01 (2-way ANOVA with Bonferroni posttest). (C) Relation between protection (CFU) and ESAT-6 specific IFN-γ producing CD4 T cells is shown as a fitted regression line with the correlation coefficient (R²). Six weeks post challenge, the mice were sacrificed and the lung cells were stimulated with ESAT-6 overlapping peptides prior to staining with anti-CD4, -CD44, and –IFN-γ. Frequencies represent IFN-γ producing ESAT-6 specific CD44⁺CD4⁺ T cells out of total CD4 T cells. Background staining from cells stimulated with medium alone has been subtracted. Data represent the mean of +SEM of a minimum of five mice per group in two individual experiments.