Identification and evaluation of new Mycobacterium bovis antigens in the in vitro interferon gamma release assay for bovine tuberculosis diagnosis

Bovine tuberculosis (bTB) is a common zoonotic disease, caused by Mycobacterium bovis (M. bovis), responsible for significant economic losses worldwide. Its diagnosis is based on the detection of cell mediated immunity under the exposure to protein purified derivative tuberculin (PPD), a complex and poorly characterized reagent. The cross-reactivity to non-tuberculous mycobacterium species (false-positive results) has been crucial to develop a more proper antigen. In the present study, we selected six M. bovis Open Reading Frames (Mb1992, Mb2031c, Mb2319, Mb2843c, Mb2845c and Mb3212c) by in-silico analysis and evaluated them in experimental and natural infection; none of these antigens had been previously assessed as diagnostic antigens for bTB. The reactivity performance was tested in animals with both positive and negative Tuberculin Skin Test (TST) results as well as in cattle infected with Mycobacterium avium subesp. paratuberculosis (MAP). The six recombinant antigens individually induced an IFN-γ response, with overall responder frequency ranging from 18.3 to 31%. Mb2845c was the most valuable antigen with the potential to discriminate TST-positive cattle from either TST-negative or MAP infected animals. Mb2845c showed similar performance to that observed with ESAT-6 and PPD-B among TST and MTC specific-PCR positive animals, although this result needs to be proven in further studies with a higher sample size. Our data confirm the feacibility to implement bioinformatic screening tools and suggest Mb2845c as a potential diagnostic antigen to be tested in protein cocktails to evaluate their contribution to bTB diagnosis.

Instituto de Biotecnología

Fil: Eirin, Maria Emilia.Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Biotecnología; Argentina

Fil: Macias, Analía. Universidad Nacional de Río Cuarto. Facultad de Agronomía y Veterinaria; Argentina

Fil: Magnano, Gabriel. Universidad Nacional de Río Cuarto. Facultad de Agronomía y Veterinaria; Argentina

Fil: Morsella, Claudia Graciela. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina

Fil: Mendez, Laura Luján. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina

Fil: Blanco, Federico Carlos. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Biotecnología; Argentina

Fil: Bianco, María Veronica. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Biotecnología; Argentina

Fil: Severina, Walter. Actividad privada; Argentina

Fil: Alito, Alicia Elsa. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Biotecnología; Argentina

Fil: Pando, Maria de Los Angeles. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; Argentina

Fil: Singh, Mahavir G. LIONEX GmbH; Alemania

Fil: Spallek, Ralph. LIONEX GmbH; Alemania

Fil: Paoliochi, Fernando. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce. Laboratorio de Bacteriología; Argentina

Fil: Bigi, Fabiana. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Biotecnología; Argentina

Fil: Cataldi, Angel Adrian. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Biotecnología; Argentina