Figure 2.

Interferon-γ responses upon M. bovis infection of cattle. Whole blood cultures were stimulated with 1 mg/mL rESAT-6:CFP-10 (panel (A)), 20 mg/mL M. bovis PPD (panel (B)), or medium alone (no stimulation) at 39 °C/5% CO₂ for 20 h. Stimulated plasma were harvested, and IFN-γ concentrations were determined by ELISA (Bovigam, Prionics, Ag). Values represent mean (±standard error) responses to antigen minus the response to media alone (D OD) for non-infected cattle (controls, closed squares) or cattle infected with M. bovis strain Ravenel (open triangles) or strain 95-1315 (closed inverted triangles). All responses elicited after challenge with M. bovis (10⁵ CFU MBO Ravenel by aerosol either strain) exceeded (p < 0.05) respective responses in non-infected (control) cattle. Responses elicited by M. bovis Ravenel infection did not differ (p > 0.05) from responses elicited by M. bovis 95-1315.