RESISTANCE TO COCCIDIOSIS (EIMERIA-FERRISI) IN C57BL-6 MICE - EFFECTS OF IMMUNIZATION AND TRANSFER-FACTOR

For studies of resistance to Eimeria ferrisi, C57BL/6 mice were immunized with infectious oocysts and treated with dialyzable transfer factor (TFd). The TFd was prepared from a calf resistant to Eimeria bovis infection and reactive to coccidian antigens by skin test and by lymphocyte stimulation. Significant resistance was induced by a single prophylactic treatment with bovine TFd, either administered orally in drinking water or injected systemically. TFd reduced both the lethality of the infection and the total oocyst output in the feces of the infected animals. Single doses of infectious oocysts failed to increase the resistance of the mice to coccidiosis. Several consecutive large doses were required to induce resistance comparable to that produced by a single dose of bovine TFd Single dose infectious oocysts did produce resistance when outbred Swiss-Webster mice were used. The results suggest that C57BL/6 mice have a genetically determined defect in their cell-mediated immune response to E. ferrisi infection and that TFd may augment their normally low response and thus confer resistance to infection by this organism. © 1979.