Production of Mycobacterium bovis Antigens Included in Recombinant Occlusion Bodies of Baculovirus.

Bovine tuberculosis (bTB) is a disease produced byMycobacterium bovisthat affects livestock, wild animals, and humans. The classical diagnostic method to detect bTB is measuring the response induced with the intradermal injection of purified protein derivative ofM. bovis(PPDb). Another ancillary bTB test detects IFN-gamma produced in whole blood upon stimulation with PPDb, protein/peptide cocktails, or individual antigens. Among the most usedM. bovisantigens in IFN-gamma assays are the secreted proteins ESAT-6 and CFP-10, which together with antigen Rv3615c improve the sensitivity of the test in comparison to PPDb. Protein reagents for immune stimulation are generally obtained fromEscherichia coli, because this bacterium produces a high level of recombinant proteins. However,E. colirecombinant antigens are in general contaminated with lipopolysaccharides and other components that produce non-specific IFN-gamma secretion in in vitro assays. In this work, we produced the relevant ESAT-6, CFP-10, and Rv3615cM. bovisantigens as fusions to the polyhedrin protein from the baculovirus AcMNPV. We obtained chimeric proteins effectively incorporated to the occlusion bodies and easily purified the recombinant polyhedra with no reactive contaminants. In an IFN-gamma assay, these fusion proteins showed equivalent sensibility but better specificity than the sameM. bovisproteins produced inE. coli.(c) 2020 S. Karger AG, Basel