Figure 2.

Low dose, but not high dose, H56 vaccination post-exposure reduces bacterial loads and lung pathology. (A) lung bacterial loads (log₁₀ CFU) 37 weeks after Mycobacterium tuberculosis challenge from mice vaccinated with the indicated dose of H56 in the post-exposure models. The histopathology data in (B,C) also derives from this experiment (Figure S1B in Supplementary Material, Exp#1). Symbols represent individual mice; lines represent mean ± SEM. (B) representative hematoxylin and eosin (H&E) stains (left panels) and inducible nitric oxide synthase (iNOS) immunohistochemistry (IHC; right panels) of lung tissue from the indicated vaccine groups. Regions of higher magnifications are indicated by inserts (dotted white lines) in lower magnification panels, with magnifications (20×, 100×) indicated above panels. (C) The overall lesion size, number of lesions, and average area affected by tuberculosis inflammation per section are shown. Symbols represent individual mice; lines represent medians. *p < 0.05 by Kruskall–Wallis with Dunn’s posttest for multiple comparisons. (D) extent of lung inflammation 2 weeks after first and 1 week after second and third post-exposure vaccinations (corresponding to 12, 14, and 17 weeks p.i.) as assessed by H&E staining is shown in a separate experiment. Symbols represent mean ± SEM of n = 4–5 mice/group. Differences between vaccine groups were assessed using one-way ANOVA and Tukey’s posttest for multiple comparisons. Statistical significant differences are marked by asterisks, *p < 0.05, **p < 0.01. These experiments were performed once each.