HUMORAL IMMUNE-RESPONSES TO THEILERIA-PARVA IN CATTLE AS MEASURED BY 2-DIMENSIONAL WESTERN BLOTTING

Humoral immune responses to schizont antigens from six stocks of Theil eria parva were compared by two-dimensional Western blotting using ser a from cattle that had been infected with a T. parva stock or a clone. Isoelectric points of a polymorphic immunodominant molecule (PIM) of schizonts that induces strong antibody responses in cattle ranged from acidic to basic. Molecular masses (Mr) of the PIM of the respective T . parva stocks were as follows: T. parva Muguga, 86 kDa; Mariakani, 83 kDa; Marikebuni, 83 kDa; Uganda, 83 kDa; T. parva Boleni, 83 kDa; and T. pawa 7014, 100 kDa. Among nine cattle infected with TT: parva Mugu ga, four produced antibodies to a basic antigen having an Mr of 32 kDa . The PIM of T. parva Muguga, T. parva Boleni, and T. parva 7014 react ed strongly with serum obtained from an animal that had been infected with T. pawa Muguga. Two-dimensional Western blotting using antischizo nt monoclonal antibodies enabled us to differentiate between stocks of T. parva.