Submitted to: North Central Conference of Veterinary Laboratory Diagnosticians
Publication Type: Abstract Only
Publication Acceptance Date: October 2, 1995
Publication Date: N/A
Technical Abstract: Listeria monocytogenes infection of ruminants causes abortions, CNS symptoms and death. Serological diagnosis of infection have relied on whole cell agglutination assays, but because of cross-reactive antigens from other bacteria, the tests are not very specific. We have purified listeriolysin O (LLO), and used it as the diagnostic antigen for infection in sheep. Sheep experimentally infected with L. monocytogenes, L. ivanovii, or L. innocua, as well as controls, were bled periodically, and their serum tested in an ELISA to determine the anti-LLO reactivity. Peripheral blood lymphocytes were isolated and tested in a blastogenesis assay using LLO as antigen. Each of the sheep was skin tested using LLO and a heat-killed whole cell suspension of each of the Listeria species. By 14 days postinfection, the anti-LLO reactivity was evident in the L. monocytogenes-infected sheep. Even though the agglutination titers of the sheep infected with the other Listeria species increased postinfection, they did not develop anti-LLO reactivity. The blastogenesis assay and the skin test gave similar results with only the L. monocytogenes-infected sheep showing a positive reaction. We feel that purified LLO can be used to detect animals that have been infected with L. monocytogenes and hopefully will be useful in distinguishing chronically infected carrier animals from those that have recovered.