AN INDIRECT ENZYME-LINKED IMMUNOASSAY (ELISA) FOR DEMONSTRATION OF ANTIBODIES TO NEOSPORA-CANINUM IN SERUM AND MILK OF CATTLE

An indirect enzyme-linked immunosorbent assay (ELISA) for detection of antibodies to Neospora caninum in serum from cattle is described, Ext racted tachyzoite proteins incorporated into immunostimulating complex es (iscoms) were used as coating antigen and a mouse monoclonal antibo dy to bovine immunoglobulin G1 as conjugate. Western blot analysis of the iscom preparation revealed a restricted number of antigens compare d with whole parasite homogenates. When probed with a serum from an ex perimentally infected calf, heavily stained antigens with apparent mol ecular masses of 28, 35, 45 and 78 kDa were seen, The sensitivity and specificity of the ELISA was 100% and 96%, respectively, against an in direct fluorescent antibody test as indicator of true status, The appl icability of the ELISA for demonstration of antibodies in milk was eva luated and the agreement between serum and milk ELISA was 95%.