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Publisher Summary This chapter describes the artificial acquired immunity to Eimeria bovis infections in cattle. The first experiment was conducted with eight experimental and four control calves. Three of four experimental which had received oral inoculations of soluble extract from ruptured oocytes, sporulated and unsporulated of Eimeria bovis were resistant to subsequent challenge with 100,000 viable, sporulated oocysts. The remaining four experimentals received oral inoculations of heat attenuated, intact, sporulated oocysts, and were immune to the challenge. A second experiment conducted with four experimental, and four control calves indicated that the four experimentals that had received oral inoculations of heat attenuated merozoites were not resistant to subsequent challenge. No alteration of the intensity of toxic effects was observed in the 14 experimental calves the attempted immunization. Differential leukocyte counts revealed an eosinophilia in only one calf but a marked lymphocytosis in all 29 calves during both antigen inoculations and challenge infections. |
