Mice were infected with 37 ± 32 CFU of M.tb Erdman by aerosol and euthanized at day 21 of infection. IFN-γ present in vivo was quantified by ELISA in homogenized lung tissue (A). M.tb lung burdens were calculated by serially diluting the homogenized lung tissue onto supplemented 7H11 agar plates (B). Results are the average plus SEM from two (A) or two to four (B) independent experiments, each with 5 mice per group, total number per strain: n = 10–20. Statistical significance was determined by the Student’s t-test (C57BL/6 vs. C57BL/6 H-2k) and one-way ANOVA with Tukey’s post-test (C57BL/6 H-2k, CBA/J, C3H/HeJ), *p<0.05.