FIG. 4.

Single-dose immunization with mc²6020 protects and prolongs the survival of CD4^−/− mice with TB. CD4^−/− mice were immunized subcutaneously with mc²6020 and challenged with virulent M. tuberculosis Erdman by the aerosol route at 3 months postimmunization. The CFU numbers reflect the bacterial burdens at 28 days post aerosol challenge in the lungs (A) and spleen (B). Asterisks (**, P < 0.001; *, P < 0.01) indicate statistically significant differences between the experimental and unvaccinated control groups. (C) Survival of CD4^−/− mice (n = 9 to 11) immunized subcutaneously with a single dose of mc²6020 or BCG-P and challenged 3 months later with virulent M. tuberculosis Erdman by the aerosol route. Unvaccinated mice served as naive controls.