Toward the development of diagnostic assays to discriminate between Mycobacterium bovis infection and bacille Calmette-Guerin vaccination in cattle

A scientific review of the recent sharp increase in bovine tuberculosis in Great Britain has concluded that the development of a cattle vaccine holds the best prospect for long-term disease control. It is important to develop a diagnostic test that differentiates between vaccinated and Mycobacterium bovis-infected animals, to ensure that test-and-slaughter control strategi es can continue alongside vaccination. The mycobacterial antigens ESAT-6, M PB64, and MPB83 are expressed at high levels in M. bovis but are expressed at low levels or not at all in bacille Calmette-Guerin (BCG) Pasteur. Promi scuous bovine T cell epitopes of these antigens were identified and formula ted into a peptide cocktail. This cocktail and a cocktail composed of recom binant forms of the 3 antigens was able to distinguish cattle infected with virulent M. bovis from those vaccinated with BCG and from those sensitized to avian tuberculin in lymphocyte transformation and interferon-gamma assa ys.