a). SDS-PAGE of proteins released into the supernatant during erythrocyte invasion. b, c, d). Proteins recognised by serum of rabbit, representative calf C139 and sheep S-M-SC respectively by Western blotting. Lane S, supernatant of invasion assay without parasites. Lane P, supernatant of invasion assay with parasites. The bars on the left of each photograph indicate the molecular masses of standard markers. Arrows indicate B. divergens-derived proteins. Band Nos. 1 to 11 are antigens which might be involved in the invasion process.