Protein 20, an immunodominant surface antigen of Eimeria bovis.

Autoradiography identified six 125I-labeled proteins, ranging in molecular weight (Mr) from 20,000 to approximately 110,000, on the plasmalemma of Eimeria bovis sporozoites. Immunoblotting with bovine antiserum generated by intravenous inoculations of sporozoites and with immune serum generated by per os inoculations of oocysts revealed that protein 20 (i.e., 20,000 Mr) was an immunodominant antigen on the surface of E. bovis sporozoites.