Submitted to: American Association of Veterinary Parasitologists Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: May 20, 1998
Publication Date: N/A
Technical Abstract: The present study was designed to evaluate the cell subsets and cytokines which lead to protective immunity in pigs against toxoplasmosis. Recent field surveys have shown a continuing prevalence of this foodborne disease. The major strategy for prevention of toxoplasmosis in swine is the identification of resistance factors and of vaccines or specific T. gondii antigens which induce protective responses. Despite the extensive literature on immunity to T. gondii in mice and humans, almost nothing is known of swine immune responses to this infection. Serologic titers have been reported for swine but these are highly variable and, as with other species, not predictive of effective immunity. This study was designed to define the protective immune response to T. gondii infection and to determine whether genetic background would influence resistance to this infection. A group of 24 piglets of different swine leukocyte antigen (SLA) haplotypes were evaluated for a period of 6 weeks after infection with ~500 T. gondii oocysts. Cells subsets from peripheral blood were tested using a broad panel of monoclonal antibodies (mAb) that identify the most important swine B and T cell subsets. Due to the important role of the immune cytokine, interferon-g (IFN- g), in the prevention of human and murine T. gondii infection, we tested the ability of swine peripheral blood lymphocytes to produce this cytokine using the cytokine specific capture ELISA. Parasite burden was assessed in tongue and brain tissues from all pigs after necropsy by bioassay in mice and cats to determine whether genetically resistant pigs can be identified. These studies should provide valuable information on controlling toxoplasmosis in pigs.