ARS | Publication request: Assessment of OmpATb as a Novel Antigen for the Diagnosis of Bovine Tuberculosis

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: August 25, 2009
Publication Date: August 25, 2009
Citation: Schiller, I., Schroder, B., Vordermeier, H.M., Waters, W.R., Palmer, M.V., Thacker, T.C., Whelan, A., Hardegger, R., Marg-Haufe, B., Raeber, A., Oesch, B. 2009. Assessment of OmpATb as a Novel Antigen for the Diagnosis of Bovine Tuberculosis [abstract].

Technical Abstract: In search for better tools to control bovine tuberculosis, the development of diagnostic tests with improved specificity and sensitivity has a high priority. We chose to search for novel immunodiagnostic reagents. In this study, Rv0899 (Outer membrane protein A of Mycobacterium tuberculosis, OmpATb) was evaluated as a stimulation antigen in a IFN-gamma release assay to diagnose bovine tuberculosis. OmpATb induced IFN-gamma responses in cattle experimentally infected with M. bovis as early and as persistently as ESAT-6 and CFP-10, the current lead diagnostic antigens. In naturally infected cattle, OmpATb stimulated IFN-gamma production in 22 of 26 animals (85%). Importantly, OmpATb detected a portion of M. bovis-infected cattle which did not respond to ESAT-6 and CFP-10 (5 of 6 cattle). The combined diagnostic sensitivity of OmpATb, ESAT-6 and CFP-10 in a pre-selected group consisting of naturally TB-infected cattle with an overrepresentation of ESAT-6/CFP-10 non-responsers was 96% (25 of 26 animals). Specificity of OmpATb in uninfected cattle was 100% (27 cattle tested, 12 of them reacted false positive with tuberculins). In summary, our results indicate that OmpATb has the potential to enhance the sensitivity of previously described diagnostic tests based on ESAT-6 and CFP-10, and that the combined use of OmpATb, ESAT-6, CFP-10 and other proteins may achieve at least equal sensitivity than PPDs yet, at higher specificity. Further studies evaluating the diagnostic performance of OmpATb in combination with other proteins are ongoing.