In this study, we characterized the role of Rv2617c in the virulence of Mycobacterium tuberculosis. Rv2617c is a protein of unknown function unique to M. tuberculosis complex (MTC) and Mycobacterium leprae. In vitro, this protein interacts with the virulence factor P36 (also named Erp) and KdpF, a protein linked to nitrosative stress. Here, we showed that knockout of the Rv2617c gene in M. tuberculosis CDC1551 reduced the replication of the pathogen in a mouse model of infection and favored the trafficking of mycobacteria to phagolysosomes. We also demonstrated that Rv2617c and P36 are required for resistance to in vitro hydrogen peroxide treatment in M. tuberculosis and Mycobacterium bovis, respectively. These findings indicate Rv2617c and P36 act in concert to prevent bacterial damage upon oxidative stress.
Bovine tuberculosis (bTB) is a disease produced by Mycobacterium bovis that 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 of M. bovis (PPDb). Another ancillary bTB test detects IFN-γ produced in whole blood upon stimulation with PPDb, protein/peptide cocktails, or individual antigens. Among the most used M. bovis antigens in IFN-γ 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 from Escherichia coli, because this bacterium produces a high level of recombinant proteins. However, E. coli recombinant antigens are in general contaminated with lipopolysaccharides and other components that produce non-specific IFN-γ secretion in in vitro assays. In this work, we produced the relevant ESAT-6, CFP-10, and Rv3615c M. bovis antigens 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-γ assay, these fusion proteins showed equivalent sensibility but better specificity than the same M. bovis proteins produced in E. coli.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.