FIG. 6.

Proliferation of the mycolactone A/B-producing strain 98-912, mycolactone C-producing strain 94-1327, or mycolactone-negative strain 5114 in wild-type and TNF receptor-deficient mice. Mice (WT [closed symbols] or TNF-P55 KO [open symbols]) were infected subcutaneously in the left hind footpad with 5.3 log₁₀ AFB of M. ulcerans 5114 (diamonds), 94-1327 (triangles), or 98-912 (squares). The number of AFB in homogenates from four footpads in each infected group was counted at the indicated time points. WT mice control the proliferation of M. ulcerans 5114 but do not eliminate the infection, whereas TNF-P55 KO mice are more susceptible to this strain. An increase in bacterial counts was also found in the footpads of TNF-P55 KO mice infected with strain 94-1327 compared with the WT mice. No significant differences were found for mice infected with M. ulcerans 98-912. For ethical reasons, mice were sacrificed after the emergence of ulceration. Statistical differences were determined by comparing TNF-P55 KO mice with WT mice. Calculations were performed using Student's t test. *, P < 0.05; **, P < 0.01; ***, P < 0.001. Results are from one representative experiment out of two independent experiments.