Fig. 6

Comparison of the infection model with M. bovis. To determine how infection outcomes may change using a pathogenic tuberculous mycobacterium, the same infection strategy was repeated using strep-R M. bovis. A C57BL/6 mice were given 20 mg of streptomycin or no pre-treatment followed by 2 consecutive doses of strep-R M. bovis 24-hours apart. Mice were sacrificed 4- and 24-weeks post-infection and organs were assessed for CFUs. B–D Strep-R M. bovis CFUs were assessed between mice given streptomycin pre-treatment or no pre-treatment in the large intestine (B), small intestine (C), MLNs (D) and lungs (E) at each timepoint (*p < 0.05, **p < 0.01). F Survival was monitored between groups over the 24-week experiment. Two mice were flagged for euthanasia at 5-weeks (mouse 1) and 15-weeks (mouse 2) post-infection. G The histopathology of the lungs was assessed for the 2 mice that reached endpoint. Shown are representative images of sections of their lungs (H&E, original magnification x40). H At the experimental endpoint of 24-weeks, the histopathology of the lungs was assessed for the surviving mice. Representative images of the lungs sections (x40) from streptomycin pre-treated mice are pictured