ID93+EmT4™ provides prophylactic pulmonary protection against 2 M.tb isolates at 4 wk post-challenge. Cohorts of mice receiving saline, BCG, EmT4™ or ID93+EmT4™ vaccination regimens were then challenged with a LDA of either M.tb HN878 (A-B) or M.tb H37Rv (C, D) 4 wk after the third immunization. Bacterial burden was assessed by colony forming units (CFU) in lung (A, C) and spleen (B, D) organ homogenates 4 wk after challenge. Bars show the mean ± SEM and dots represent individual mice (n = 5-7/group). Asterisks indicate statistical significance compared to the saline group, where *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001 using 1-way ANOVA with Dunnett’s multiple comparisons test.