Figure 3.
Analysis of vaccine efficacy of bacillus Calmette-Guerin (BCG) in a mouse model of aerosol infection with unencapsulated and encapsulated Mycobacterium tuberculosis. Five C57BL/6 mice were immunized subcutaneously with 1 × 106 colony-forming units (CFU) of encapsulated or unencapsulated BCG or sham vaccinated with phosphate-buffered saline. Six weeks later, animals were challenged by aerosol infection with 50–100 CFU of virulent unencapsulated or encapsulated M. tuberculosis strain H37Rv. A, Lung CFU in mice infected with unencapsulated (left) or encapsulated (right) M. tuberculosis at 4 weeks. B, Splenic CFU in mice infected with unencapsulated (left) or encapsulated (right) M. tuberculosis at 4 weeks. Bars represent means and standard errors of the mean. Results shown are representative of 2 independent experiments, each with 5 mice per group. *P < .05, **P < .01, and ***P < .001, by 1-way analysis of variance with the Tukey post hoc test. C and D, Representative images of hematoxylin-eosin–stained lungs of C57BL/6 mice immunized with encapsulated or unencapsulated BCG and challenged with encapsulated or unencapsulated M. tuberculosis. Abbreviation: NS, not significant.