FIG. 7.
Hepatic (A) and splenic (B) Brucella CFU from IRF-1−/− mice compared to IRF-1+/+ mice infected with B. abortus cbp, cyd, and bap mutants (5 × 105 CFU). Mice were at the moribund stage or 4 weeks postinoculation. Hepatic bap CFU detected from IRF-1+/+ and IRF-1−/− mice showed a ∼3.5-log difference at 12 days postinoculation (P < 0.005), indicating the serious bacterial burden in IRF-1−/− mice. No difference in bacterial growth was noted in the spleens of IRF-1+/+ and IRF-1−/− mice. However, attenuated cbp and cyd mutants were controlled by IRF-1−/− mice at 4 weeks postinoculation.