The detection of specific complement-fixing antibodies in serum of white-tailed deer (Odocoileus virginianus) with Theileria infection.

A complement-fixation (CF) antigen which has been prepared from Theileria infected erythrocytes is capable of reacting to specific serum antibodies of deer acutely infected with Theileria. No sera from 17 deer known to be free of Theileria infection reacted positively to the CF test. Of 35 tests on sera from 12 infected deer having a parasitemia of 2% or less and no accompanying anemia, only 10 (29%) were positive, 2 (6%) were suspicious, and 23 (66%) were negative. Of 65 tests on 8 acutely infected deer, 49 (75%) were positive, 4 (6%) were suspicious and 12 (18%) were negative. Of the 8 deer in which acute theileriasis occurred all reacted to Theileria antigen at one time or another.A significant correlation was found between CF titers and the degree of parasitemia in acute infections. Rabbits were hyperimmunized using erythrocytes from either normal or Theileria infected deer. Reciprocal absorption of the hyperimmune sera with Theileria and normal erythrocytic antigens demonstrated the presence of antibodies specific for Theileria.