Antibody Responses of Cervids (Cervus elaphus) following ExperimentalMycobacterium bovisInfection and the Implications for Immunodiagnosis

Abstract

Captive and free-ranging wildlife animals are implicated in the maintenance and transmission of bovine tuberculosis and therefore pose a significant obstacle to eradication of the disease from domestic livestock. The current antemortem diagnostic method, the intradermal tuberculin skin test, is impractical for routine use with many wild animals. Antibody-based assays are particularly attractive because the animals are handled only once and immediate processing of the sample is not required. This report characterizes the antibody responses of red deer-elk hybrids (Cervus elaphus) against Mycobacterium bovis and subsequently evaluates the diagnostic performance of select antigens in a rapid-test format. Sequential serum samples were collected from 10 animals experimentally infected with M. bovis and 5 noninfected animals over a 7-month period postinfection (p.i.). Samples were evaluated by enzyme-linked immunosorbent assays, immunoblot analyses, and multiantigen print immunoassays for seroreactivity to mycobacterial antigens. Although all infected animals produced antibodies to M. bovis protein antigens, there was significant animal-to-animal variation in the kinetics and magnitudes 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 p.i.). Antibody responses were boosted by injection of tuberculin for intradermal tuberculin skin testing. Comparison of single-antigen (fluorescence polarization assay) with multiantigen (CervidTB STAT-PAK) rapid tests demonstrated that a highly sensitive and specific serodiagnostic test for tuberculosis in cervids will require multiple and carefully selected seroreactive antigens covering a broad spectrum of antibody specificities.Mycobacterium bovis, the etiological agent of bovine tuberculosis (TB), has an extraordinarily broad mammalian host range that includes humans, domestic livestock, and wildlife. Globally, several wildlife species have been implicated in the maintenance and transmission of M. bovis. In North America, these include white-tailed deer (Odocoileus virginianus) in northeastern Michigan (37), elk (Cervus elaphus) in and around Riding Mountain National Park, Manitoba, Canada (31), and wood bison (Bison bison athabascae) in and around Wood Buffalo National Park, Alberta, Canada, and the Northwest Territories (31). The continued transmission of M. bovis from free-ranging wildlife reservoirs to domestic livestock results in significant economic losses and is a significant barrier to the success of national eradication and control programs (5). Similarly, TB agent-infected captive wildlife maintained in farms or animal parks (e.g., zoos or game farms) may also serve as foci of infection for domestic animals, free-ranging wildlife, and humans (7, 42). The existing methods for diagnosing bovine TB that rely on cell-mediated immun...

Sensitivity, Specificity, and Confounding Factors of Novel Serological Tests Used for the Rapid Diagnosis of Bovine Tuberculosis in Farmed Red Deer ( Cervus elaphus )

“…The MAPIA revealed that some of the sera from deer experimentally infected with M. avium subsp. paratuberculosis which produced false-positive responses in the CervidTB STAT-PAK test reacted with MPB83, a key antigen in the specific antibody detection during M. bovis infection (7,9). This unexpected finding is difficult to explain, because the MPB83 protein is not produced by M. avium subsp.…”

“…The high number of false-positive responses in the group only vaccinated against Johne's disease (group 4B) at the final bleed is likely to have resulted from the boosting of antibody levels following skin testing with bovine PPD. It is recognized that tuberculin testing can boost antibody responses to certain mycobacterial antigens in M. bovis-infected animals (6,7,19). These results reemphasize the limitations of the currently available vaccines against paratuberculosis when confirmatory serological tests for bovine TB are used following skin testing.…”

“…The CervidTB STAT-PAK test is a single-directional lateral-flow serological test which can provide a quick determination of the presence of M. bovis antibody (7,9). The test uses colored latex-based lateralflow technology and a cocktail of selected M. bovis antigens, including ESAT-6, CFP10, and MPB83.…”

Diagnostic Value of Animal-Side Antibody Assays for Rapid Detection of Mycobacterium bovis or Mycobacterium microti Infection in South American Camelids

“…Earlier work demonstrated that most of alpacas and llamas with TB produced IgG antibodies against the MPB83 protein, irrespective of whether the etiologic agent was M. bovis or M. microti (7,22). This antigen is known to be a major serological target for the immune responses to infections caused by organisms of the M. tuberculosis complex in various host species (13,15,23,40,41). Both RT and the DPP assay include the MPB83 protein in their test antigen composition, which could partly explain the reasonable agreement of the tests with respect to identification of infected animals.…”

Comparison of Three Immunodiagnostic Assays for Antemortem Detection of Mycobacterium Bovis Stimulation in Domestic Cats

“…Recent studies have proven the rapid test to be useful in detecting M. bovis infections in llamas (Llama glama), elk (Cervus elaphus), white-tailed deer (Odocoileus virginianus), wild boar (Sus scrofa), Eurasian badgers, brushtail possums (Trichosurus vulpecula), and meerkats (Suricata suricatta); however, validation of the rapid test for domestic cats has yet to be achieved. 6,9,10,12,16,17,26 Multiple antigen print immunoassay identified 16/83, 16 kDa, MPB83, and MBCF as major antigens involved in the humoral immune response in sensitinogen-stimulated cats. Visually all sensitinogen-stimulated cats reacted consistently to antigen MBCF and less consistently to 16/ 83, 16 kDa, and MPB83 antigens (Fig.…”