Isolation and purification of cationic proteins from microaerophilous stationary phase culture supernatants of Babesia bigemina.

Babesia bigemina was maintained in short-term culture by microaerophilous s tationary phase culture system. The pooled 3 day culture supernatants were centrifuged at 12000 x g for 30 min and the supernatant collected was filte red through 0.45 mu m millipore filter. A two-step protocol was used for pu rification, of cationic babesial proteins by ammonium sulphate precipitatio n and CM-cellulose chromatography, Five polypeptides were identified as cat ionic babesial proteins in Coomassie blue stained polyacrylamide gradient g el (5-15%) under reducing conditions in the molecular weight range (Mr) of 150 to 48 kDa. The partially purified babesial merozoite antigen revealed m ajor polypeptides in the Mr of 255 to 75 kDa with an overwhelming contamina tion of host corpuscular proteins of 290-28 kDa.