Expression and field evaluation of new Mycobacterium bovis antigens

• Published in: Veterinary immunology and immunopathology 2024-07, Vol.273, p.110788, Article 110788
• Main Authors: Villafañe, Luciana, Rocha, Rosana Valeria, Bigi, María Mercedes, Klepp, Laura Inés, Taboga, Oscar Alberto, Forrellad, Marina Andrea, López, María Gabriela, Bigi, Fabiana
• Format: Article
• Language: English
• Subjects: Animals; Antigens; Antigens, Bacterial - immunology; Bacterial Proteins - genetics; Bacterial Proteins - immunology; Cattle; EsxG; IFN-γ assay; Mb0309; Mycobacterium bovis; Mycobacterium bovis - immunology; Recombinant Proteins - genetics; Recombinant Proteins - immunology; Tuberculin Test - veterinary; Tuberculosis, Bovine - immunology
• ISSN: 0165-2427; 1873-2534; 1873-2534
• DOI: 10.1016/j.vetimm.2024.110788

Bovine tuberculosis (bTB) represents a threat to livestock production. Mycobacterium bovis is the main causative agent of bTB and a pathogen capable of infecting wildlife and humans. Eradication programs based on surveillance in slaughterhouses with mandatory testing and culling of reactive cattle have failed to eradicate bTB in many regions worldwide. Therefore, developing effective tools to control this disease is crucial. Using a computational tool, we identified proteins in the M. bovis proteome that carry predictive binding peptides to BoLADRB3.2 and selected Mb0309, Mb1090, Mb1810 and Mb3810 from all the identified proteins. The expression of these proteins in a baculovirus-insect cell expression system was successful only for Mb0309 and Mb3810. In parallel, we expressed the ESAT-6 family proteins EsxG and EsxH in this system. Among the recombinant proteins, Mb0309 and EsxG exhibited moderate performance in distinguishing between cattle that test positive and negative to bTB using the official test, the intradermal tuberculin test (IDT), when used to stimulate interferon-gamma production in blood samples from cattle. However, when combined as a protein cocktail, Mb0309 and EsxG were reactive in 50 % of positive cattle. Further assessments in cattle that evade the IDT (false negative) and cattle infected with Mycobacterium avium paratuberculosis are necessary to determine the potential utility of this cocktail as an additional tool to assist the accurate diagnosis of bTB. •Mb0309 exhibits predictive binding to alleles of BoLADRB3.2.•Both EsxG and Mb0309 were effectively expressed using a baculovirus-insect cell system.•In an IFN-γ release assay, EsxG and Mb0309 displayed reactivity in 50 % of cattle with bovine tuberculosis (bTB).