Figure 7.

Histology of the lung and spleen in TB-challenged mice. Vaccinated C57BL/6 mice were challenged by aerosol with 5 × 10⁶ CFU virulent M. tuberculosis H37Rv strain. Six weeks after infection, lung (A–C,G) and spleen (D–F,H) tissue sections from PBS group (A,D), BCG group (B,E), and rBCG::Ag85A group (C,F) were prepared for acid-fast staining (× 4). The number of bacteria in the lung and spleen from the group immunized with rBCG::Ag85A (C,F) was lower than PBS group (A,D) and BCG group (B,E). Vaccination with BCG and rBCG::Ag85A strains strongly reduced bacterial load in the lung and spleen in C57BL/6 mice (G,H). Data depicted are the mean values ± SEM. Statistical significance was determined by a Student's t-test (^**P < 0.01).