Figure 6

BLI of C57BL/6J mice infected subcutaneously with Δ caf1 Δ psaA Y. pestis carrying the pGEN- luxCDABE vector. (A) Mice were inoculated with ~200 CFU of the double mutant. Images correspond to infected animals at different time points post inoculation (shown in hpi). A color bar serves as a reference for the radiance scale (p/sec/cm²/sr) used to standardize all images. (B) Images of superficial cervical lymph nodes, spleen and liver (from one of the mice shown in A) imaged individually after dissection. Luminescence was detected only from lymph nodes, imaged in an individual scale of radiance with a Min = 2.28e6 and Max = 4.27e7. (C) Transformed values (ln) of the mean radiance per group from the neck (left) and abdomen (right) from animals infected with Yplux⁺ (gray circles) and YpΔcaf1 ΔpsaA lux⁺ (white circles), as determined by measurements from regions of interest (ROI) of images from two independent experiments. A dotted line depicts background radiance levels. Asterisks denote statistical significance in differences between the two means compared in a time point, as determined by linear regression analysis of transformed values (*, P < 0.05; **, P < 0.005; ***, P < 0.0005). Error bars represent the standard error of the mean (SEM). Shown is a representative experiment