IDENTIFICATION OF BABESIA-BIGEMINA INFECTED ERYTHROCYTE SURFACE-ANTIGENS CONTAINING EPITOPES CONSERVED AMONG STRAINS

The presence of previously uncharacterized antigens (new antigens) on the surface of intact erythrocytes infected with three strains of Babe sia bigemina from Kenya and one each from Puerto Rico, Mexico, St. Cro ix, and Texcoco-Mexico was demonstrated by indirect immunofluorescent antibody (IFA) reactions. These antigens were not strain specific beca use antibodies in bovine immune serum to either the Mexico or Kenya is olates reacted with all seven strains tested. Homologous and heterolog ous immune serum antibodies bound a maximum of 83% and 55%, respective ly, of intact erythrocytes infected with the Kenya-Ngong strain but no t uninfected erythrocytes. Both sera caused agglutination of only infe cted erythrocytes. Antibodies eluted from the surface of glutaraldehyd e (0.25%) fixed infected erythrocytes had IFA reaction patterns among strains similar to those of immune sera before elution. Eluted antibod ies were used to determine if these antigens were protein and encoded by B. bigemina. Eluted antibodies bound seven parasite-encoded protein s of 240, 220, 66, 62, 58, 52 and 38 kDa in an erythrocyte surface-spe cific immunoprecipitation reaction of S-35-methionine labelled protein s. It was concluded that the surface of B. bigemina infected erythrocy tes had parasite-encoded proteins and that these proteins had surface exposed epitopes that were conserved among the seven strains examined which were from two continents.