|Robbe Austerman, Suelee|
Submitted to: Clinical and Diagnostic Laboratory Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/27/2004
Publication Date: 7/1/2004
Citation: Waters, W.R., Nonnecke, B.J., Palmer, M.V., Robbe Austerman, S., Bannantine, J.P., Stabel, J.R., Whipple, D.L., Payeur, J.B., Estes, D.M., Pitzer, J.E., Minion, F.C. 2004. Use of recombinant esat-6:cfp-10 fusion protein for differentiation of infections of cattle by mycobacterium bovis and by m.avium subsp. avium and m. avium subsp. paratuberculosis. Clinical and Diagnostic Laboratory Immunology. 11:729-735.
Interpretive Summary: Despite highly successful eradication efforts in several countries, tuberculosis of cattle remains a serious health concern worldwide. In addition, recent outbreaks of tuberculosis in Michigan, California, Texas, and New Mexico demonstrate that the disease is far from eliminated from the United States. Improved techniques are needed for detection of infected cattle. To develop improved tests, it is beneficial to first understand the immune response to infection. In this study, specific host responses of cattle to tuberculosis infection were determined and compared to responses by cattle infected with similar bacteria. Specific tools were determined to distinguish tuberculous cattle from those infected with related bacteria. Knowledge obtained from this study will enable more accurate detection of cattle with tuberculosis.
Technical Abstract: Immunological diagnosis of Mycobacterium bovis infection of cattle often is confounded by cross-reactive responses resulting from exposure to other mycobacterial species, especially Mycobacterium avium. Early secretory antigenic target-6 (ESAT-6) and culture filtrate protein-10 (CFP-10) are dominant interferon (IFN)-gamma-inducing antigens of tuberculous mycobacteria; and, they are absent from many environmental non-tuberculous mycobacteria. However, esat-6 and cfp-10 are present in M. avium subsp. avium (M. avium) and M. avium subsp. paratuberculosis (Map). In vitro responses to a recombinant ESAT-6:CFP-10 fusion protein by blood leukocytes from cattle naturally-exposed to M. avium or experimentally-challenged with M. avium or Map were compared to responses by M. bovis-infected cattle. Responses to heterogeneous mycobacterial antigens [i.e., purified protein derivatives (PPD) and whole cell sonicates (WCS)] were also evaluated. Tumor necrosis factor (TNF)-alpha, IFN-gamma, and nitric oxide responses by M. bovis-infected cattle to rESAT-6:CFP-10 exceeded (P<0.05) corresponding responses by cattle sensitized naturally to M. avium. Experimental infection with M. bovis, M. avium, or Map induced significant (P<0.05) IFN-gamma and nitric oxide production to WCS and PPD antigens, regardless of the mycobacterial species used for the preparation of the antigen. Responses to homologous crude antigens generally exceeded responses to heterologous antigens. Nitric oxide and IFN-g responses to rESAT-6:CFP-10 by blood leukocytes from M. bovis-infected calves exceeded (P<0.05) corresponding responses of non-infected, M. avium-infected, and Map-infected calves. Despite the potential for secretion of immunogenic ESAT-6 and CFP-10 proteins by M. avium and Map, it appears that use of the rESAT-6:CFP-10 fusion protein will be useful for the detection of tuberculous cattle in herds with pre-existing sensitization to M. avium and/or Map.