Screening of molecular markers of Mycobacterium bovis and preliminary evaluation in guinea pigs

Abstract:

[Background] Bovine tuberculosis (BTB) is a chronic infectious disease caused by Mycobacterium bovis, a part of the Mycobacterium tuberculosis complex, posing threats to cattle health, livestock economies, and public health. [Objective] In order to screen new diagnostic molecular markers of Mycobacterium bovis and establish new diagnostic method for bovine tuberculosis. [Methods] Using isotopic labeling-based relative and absolute quantification techniques and article screening, we identified 11 proteins (Mpb70, GroEL2, HspX, DnaK, Mpb83, EsxW, BfrB, Hrp1, EsxL, AtpD, and EsxN) for further evaluation. These recombinant proteins were then assessed for sensitization effects in a guinea pig model. [Results] At a dose of 100 μg, Mpb70, HspX, Mpb83, and EsxN induced marked delayed-type hypersensitivity (DTH) and rupture. At a dose of 50 μg, Mpb70, HspX, Mpb83, EsxW, EsxL, and EsxN provoked significant DTH. At a dose of 12.5 μg, the proteins did not induce DTH. Among the protein combinations, EsxW/EsxL/EsxN showed the highest activity, triggering robust DTH in guinea pigs. Other combinations such as EsxW/EsxL, EsxW/EsxN, and EsxL/EsxN also induced DTH, though to a lesser extent than EsxW/EsxL/EsxN. [Conclusion] Recombinant proteins Mpb70, HspX, Mpb83, EsxW, EsxL, and EsxN elicited notable DTH, demonstrating the potential as tuberculin substitutes.

Key words:guinea pig model;delayed-type hypersensitivity;recombinant protein;tuberculin