FIG. 3.

RelE1, RelE2, and RelE3 are dispensable for in vivo survival of M. tuberculosis. (A) Growth of relE mutants in macrophages. J774A.1 resting macrophages were infected with the wild-type strain (H₃₇Rv) (squares) or the ΔrelE1 (triangles), ΔrelE2 (inverted triangles), or ΔrelE3 (diamonds) mutant strain as described in Materials and Methods. At the designated time points, infected cells in triplicate wells were washed and lysed in phosphate-buffered saline (PBS) containing 0.05% SDS, and 100 μl of 10-fold serial dilutions was plated for CFU analysis. Results represent the means and standard errors of bacterial loads from three infected wells. (B and C) Growth and persistence of the relE mutants in mice. C57BL/6 mice were infected with the wild-type strain (H₃₇Rv) (squares) or the ΔrelE1 (triangles), ΔrelE2 (inverted triangles), or ΔrelE3 (diamonds) mutant strain of M. tuberculosis. The bacterial loads were determined at the indicated time points postinfection by harvesting the spleens (B) and lungs (C) of infected mice. Results represent the medians and standard errors from four mice per group.