Purification and characterization of precipitating antigens from Theileria parva.

Precipitating antigens from Theileria parva have been partially purified. Two antigens from each of the schizont and piroplasm stages of the parasite were identified; the major antigens from the two stages shared the same specificity. The antigens showed considerable molecular heterogeneity, almost certainly a result of the preparative method, and they always contained large amounts of DNA. The piroplasm antigens were of parasite nuclear origin and the schizont antigens were probably of the same origin. The antigens were weakly antigenic, and the activity against them of humoral antibody from cattle immune to East Coast fever was low. These antigens do not appear to induce protection against East Coast fever.