FIG. 2.

Rv3615c was identified as the antigen with the greatest responder frequency in M. bovis-infected cattle in our initial selection of highly expressed candidates. In this screen IFN-γ levels were measured using the Bovigam ELISA, and the level of IFN-γ production upon stimulation with Rv3615c (A) or PPD-B (B) for each animal in each group is shown. Symbols: •, uninfected cattle; ▴, M. bovis-infected cattle; ▪, BCG-vaccinated cattle; ▾, M. bovis-infected ESAT-6/CFP-10-negative (ESAT-6/CFP-10 -ve) cattle. The data are expressed as background-subtracted OD₄₅₀ (Δ OD450), and the dashed lines indicate the cutoff for positivity. Significance testing was performed using the nonparametric Wilcoxon rank sum test adjusted for multiple comparisons.