Screening and evaluation of Mycobacterium tuberculosis diagnostic antigens

In recent years, the prevalence of tuberculosis worldwide has increased, and with it, the number of drug-resistant tuberculosis strains. This has brought new challenges towards prevention and control of the disease. Therefore, it is urgent to find reliable and rapid diagnostic methods for tuberculosis in general, and for the drug-resistant forms of the disease. To this aim, we assessed 17 tuberculosis-specific protein candidates for the detection of tuberculosis-specific antibodies. First, we established an indirect ELISA method to detect anti-Mycobacterium tuberculosis IgM and IgG. We tested 453 sera and analyzed the efficacy of the protein candidates for diagnosis of tuberculosis. Next, we screened antigens rich in T cell epitopes for their ability to induce high levels of IFN-γ, in order to define their suitability does develop detection tests based on IFN-γ release assay (IGRAs). The antigens CFP-10, PPE57, 38kDa, and Rv3807 showed higher diagnostic potential for the detection of anti-tuberculosis IgM, whereas PPE57, Ag85B, CFP-10, Rv0220, and 38kDa antigens performed better for anti-tuberculosis IgG detection. Worth noting is that CFP-10, 38kDa, and PPE57 detected efficiently both IgM and IgG. Rv1987, Rv3807, PPE57, Rv0220, and MPT64 proteins alone and combinations of Rv1987 + Rv3807, 16kDa + Rv0220, and MPT64 + Rv1986 tested in IGRAs displayed a good correlation with the positive control constituted by a cocktail of ESAT-6 + CFP-10 + TB7.7 (ECT), known for their stimulating properties (r > 0.5, p < 0.01). Among these antigen candidates, Rv0220 and Rv1987 + Rv3807 were the most potent. We discovered CFP-10, 38kDa, and PPE57 for the detection of anti-M. tuberculosis IgM and IgG, and Rv0220 alone or the combination Rv1987 + Rv3807 as the strongest stimulators in IGRAs. These antigens provide new references for the screening of tuberculosis-specific antibodies and effective stimulation in IGRAs.