Fig. 1.

Bacterial load in organs of the low-dose infected mice. Bacterial load was measured by counting colony-forming units (CFU) in tissue homogenates prepared from spleens (a) and lungs (b) of mice challenged with 2 × 10⁵Mycobacterium tuberculosis H37Rv. A reduction of approximately 10-fold was observed in bacille Calmette–Guérin (BCG)-immunized mice. In mice immunized with M. vaccae, the bacterial load after 5 weeks was higher than in control mice, in spite of a decreased mortality.