Evaluation of the use of recombinant proteins of Mycobacterium bovis as antigens in intradermal tests for diagnosis of bovine tuberculosis

Abstract

The skin test with purified protein derivatives (PPD) from Mycobacterium bovis has been used for the diagnosis of bovine tuberculosis. However, due to the suboptimal specificity of this protein mixture, improved tests based on defined specific antigens are needed. In the present study, recombinant proteins from M. bovis were evaluated as antigens in the skin test. Among these proteins, EsxI, Mb0143, PE5, and PE13 are antigens tested for the first time in skin test on cattle. Sensitised and non-sensitised cattle to the inactivated AN5 strain of M. bovis were simultaneously injected with each recombinant protein, a cocktail with all recombinant proteins, M. bovis PPD, M. avium PPD and saline. Only the proteins EsxI, Mb0143 and PE5 were able to differentiate sensitised and non-sensitised cattle when 320 irg of protein was used and the reading done 24 hours post-injection. EsxI and PE5 exhibited a sensitivity level of 83.33% and specificity of 100% and 80%, respectively. The results of the present study suggest that the recombinant proteins have potential to be assessed as antigens in skin tests in cattle.