Detection of lung IL-6 and TNF-α and bacterial load in Ms_YrbE3A- and Ms_Vec-infected C57BL/6 mice. (A) Multiplex immunoassay of TNF-α and IL-6 in lung cells from C57BL/6 mice infected intratracheally for 0–21 d with 2.0 × 106 CFU of MS_Vec and MS_YrbE3A strains, while a saline control was used as the placebo. (B) Lung bacterial load of Ms_YrbE3A and Ms_Vec was detected after 0, 2, 4, and 8 d postinfection. (C,D) The detection of the cytokines IL-6 and TNF-α in the lungs of experimental mice by immunohistochemistry (left panel). The brown positive signal produced by immunohistochemistry was quantitatively expressed as integrated optical density (IOD) of IL-6 and TNF-α for the immunohistochemical detection (right panel). Significant difference (*p < 0.05, **p < 0.01, ***p < 0.001) among treatments was analyzed by a two-way ANOVA followed by the LSD test. Each sample was repeated in triplicate.