FIG. 4.

Viable bacterial counts in spleens and livers of C57BL/6 mice infected intravenously with 5 × 10³ CFU (0.5 LD₅₀) of L. monocytogenes ΔtrpS/pSP0 or 5 × 10⁷ CFU (0.25 to 0.5 LD₅₀) of the self-destructing carrier strain L. monocytogenes ΔtrpS/pSP118. (A) Bacterial loads in spleens of infected animals. (B) Bacterial loads in livers of infected animals. (C) GPT levels of infected mice at different times after infection. The dotted line indicates the mean GPT level for mice that were inoculated with a saline solution as a control. (D) Bacterial loads in spleens of animals infected with equal doses (5 × 10³ CFU each) of L. monocytogenes ΔtrpS/pSP0 and L. monocytogenes ΔtrpS/pSP118. In this experiment, a third group of mice was also infected with 5 × 10⁷ CFU of L. monocytogenes ΔtrpS/pSP118. Each symbol represents a single animal. The lines indicate the means for the experimental groups (n = 5). The results of one of two experiments are shown.