FIG 6 .
mc27901- and mc27902-derived MDR strains are attenuated in mice and protect against virulent M. tuberculosis. (A) Survival of immunocompromised SCID mice (7 mice per group) infected with H37Rv and two MDR strains, mc28248 and mc28251, via tail vein injection at a dose of 5 × 105 CFU. (B and C) Immunocompetent C57BL/6 mice were immunized with mc28248, mc28250, or BCG and challenged with H37Rv (low-dose aerosol infection) 6 weeks later. Mice were euthanized 3 and 15 weeks postchallenge to determine lung (B) and spleen (C) bacterial burden.