FIG. 1.

Dissemination of Tox⁺ B. anthracis organisms in A/J mice. (A) 9602Rlux spores (1 × 10⁴) were injected into the ears of A/J mice and then analyzed for bioluminescence at the indicated times. Images in this figure and the following figures depict photographs overlaid with false-color representations of luminescence intensity, measured in photons/s-cm²-sr and indicated on the scales, where red is most intense and blue is least intense. (Top row) Dorsal views of a single mouse at the indicated times. (Bottom row) Ventral views of the same mouse, with the infected ear hidden to allow greater sensitivity in detecting bacteria in the draining lymph node. A single representative region of interest (ROI) for the ear is depicted as a red circle at 1 h. This image series is representative of 30 infected mice. (B) The luminescence of the ears of mice was quantified at the indicated times by defining specific ROI encompassing the ear, as depicted in panel A. Five mice are represented individually in the graph as differently colored bars. The limit of detection was 1 × 10⁴ photons/s-ear. *, the corresponding mouse died. (C) A mouse infected for 72 h was dissected to determine which organs were the sources of bioluminescence. (Top left) Exterior of the infected mouse. (Top center) Dissection with displacement of the skin. (Top right) Open thorax and peritoneum. (Bottom) Uncoiled gastrointestinal tract with the strong luminescence from the neck lymph nodes and thorax blocked. (Inset) Ex vivo analysis of the kidneys and spleen. Abbreviations: LN, lymph nodes; RL, right lung; LL, left lung; St, stomach; LK, left kidney; RK, right kidney; Sp = spleen. (D) CFU were determined for the indicated organs (means plus standard deviations; n = 4).