Submitted to: Clinical and Vaccine Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/12/2008
Publication Date: 11/1/2008
Citation: Harrington, N.P., Surujballi, O.P., Prescott, J.F., Duncan, J.R., Waters, W.R., Lyashchenko, K., Greenwald, R. 2008. Antibody Responses of Cervids (Cervus elaphus) following Experimental Mycobacterium bovis Infection and the Implications for Immunodiagnosis. Clinical and Vaccine Immunology. 15(11):1650-1658. Interpretive Summary: Free-ranging Elk are wildlife reservoirs of bovine tuberculosis in Canada and captive elk are routinely tested for tuberculosis in the United States. Tuberculosis has been spread from captive elk to other deer species, cattle and bison within the United States. The presence of disease in this host seriously threatens ongoing efforts to eradicate tuberculosis from cattle. A reliable and easy blood test applicable to elk would be beneficial to tuberculosis eradication and control programs. In the present study, it was determined that elk experimentally infected with tuberculosis produce antibodies to the tuberculosis agent and that these antibodies are detectable by simple laboratory methods. These findings will be useful for the control of bovine tuberculosis in captive elk, thus, benefiting the cattle industry and potentially decreasing the spread of tuberculosis to cattle.
Technical Abstract: Captive and free-ranging wildlife are implicated in the maintenance and transmission of bovine tuberculosis (TB) and therefore pose a significant obstacle to eradication of the disease from domestic livestock. The current ante-mortem diagnostic method, the intradermal tuberculin skin test, has serious short-comings and is impractical for routine use with many wild animals. For surveillance purposes, antibody-based assays are particularly attractive because animals are handled only once and immediate processing of the sample is not required. This report characterizes the antibody responses of red deer x elk hybrids (Cervus elaphus) against Mycobacterium bovis so as to identify immunodominant antigens and subsequently evaluates the diagnostic performance of select antigens in rapid-test format. Sequential serum samples were collected from ten experimentally M. bovis-infected and five non-infected animals over a seven-month period post-infection. Samples were evaluated by enzyme-linked immunosorbent assay (ELISA), immunoblotting, and multiantigen print immunoassay (MAPIA) for seroreactivity to mycobacterial antigens. Although all infected animals produced antibody to M. bovis protein antigens, there was significant animal-to-animal variation in the kinetics and magnitude of responses and the antigens recognized. The most frequently recognized antigens included MPB83, ESAT-6, CFP10, and MPB70. Responses to some antigens such as MPB83 were consistently detected as early as 4 weeks after inoculation whereas other antigens were detected only much later (>140 days PI). Antibody responses of all assays were boosted by injection of tuberculin for intradermal tuberculin skin testing. Comparison of a single- versus multi-antigen rapid test demonstrated that a highly sensitive serodiagnostic test for TB in cervids will require the use of multiple and carefully selected TB-specific seroreactive antigens covering a broad spectrum of antibody specificities.