Biomarkers of cell-mediated immunity to bovine tuberculosis

Whole blood based assays, particularly interferon gamma (IFN-gamma) release assays (IGRAs), are used for the diagnosis of both bovine and human tuberculosis (TB). The aim of the current study was to evaluate a panel of cytokines and chemokines for potential use as diagnostic readouts indicative of Mycobacterium bovis (M. bovis) infection in cattle. A gene expression assay was used to determine the kinetics of the response to M. bovis purified protein derivative and a fusion protein consisting of ESAT-6, CFP10, and Rv3615c upon aerosol infection with similar to 10(4) cfu of M. bovis. The panel of biomarkers included: IFN-gamma, CXCL9, CXCL10, CCL2, CCL3, TNF-alpha, IL-1 alpha, IL-1 beta, IL-1Ra, IL-22, IL-21 and IL-13. Protein levels of IFN-gamma, CXCL9, and CXCL10 were determined by ELISA. Findings suggest that CXCL9, CXCL10, IL-21, IL-13, and several acute phase cytokines may be worth pursuing as diagnostic biomarkers of M. bovis infection in cattle.