A method for avoiding false-positive reactions in an enzyme-linked immunosorbent assay (ELISA) for the diagnosis of bovine paratuberculosis.

Abstract

An enzyme-linked immunosorbent assay (ELISA) was developed to detect specific antibodies against Mycobacterium paratuberculosis in bovine serum. Experiments were designed to find methods to avoid the fase-positive reactions that frequently are encounted in ELISA for the detection of antibodies to protoplasmic antigen of M. paratuberculosis. Sera examined were obtained from cattle infected with M. paratuberculosis, M. bovis, M. kansasii, or Nocardia asteroides, from cattle which were negative in bacteriological examination but positive in the complement-fixation test for paratuberculosis, and from sheep infected with Corynebacterium pseudotuberculosis. Preabsorption of tested sera with M. phlei resulted in substantially eliminating false-positive reactions. This absorption treatment had no effect on the ELISA antibody level of sera from cattle infected with M. paratuberculosis. The false-positive reactions that occur in the ELISA test for the diagnosis of bovine paratuberculosis may be controlled by preabsorption of the tested serum with M. phlei.