Fig 5. Deletion of the MEW123 RSM gene cluster increases the host inflammatory cytokine response in the murine subcutaneous infection model.

C57BL/6J mice were inoculated subcutaneously at the shaved flank and resulting lesions were dissected on day 6 post-infection for cytokine analysis (panel A) and histology (panel B). A) Shown are ELISA results of homogenized murine skin biopsy specimens from mice previously inoculated with sterile phosphate buffered saline (PBS, black bars), 1x10⁷ CFUs MEW123 (WT, red bars), or 1x10⁷ CFUs of the ΔRSM mutant (ΔRSM, blue bars). Results are pooled from biopsies of 3 mice per group with mean and SEM cytokine concentrations. A Mann-Whitney U test was used to identify significant differences in cytokine concentration; ns, not significant, * P < 0.05, ** P < 0.01. B) Representative images at 10X magnification of skin biopsies from mice inoculated with MEW123 (WT, upper row), or the ΔRSM mutant (ΔRSM, bottom row). Slides were stained with hematoxylin and eosin (H&E) for general neutrophil and overall inflammatory response, or specifically by immunohistochemistry for T cells (α-CD3) or macrophages (α-F4/80). Focal areas of intense inflammation were outlined with dashed lines for comparison.