In vitro inhibition of multiplication of Babesia bigemina by using monoclonal antibodies.

A panel of 21 monoclonal antibodies (MAb) against the erythrocytic stages of Babesia bigemina was produced. The 21 MAb could be divided into four distinct immunofluorescence groups on the basis of their patterns of binding to B. bigemina-infected erythrocytes. Nine MAb positive in the indirect immunofluorescent antibody test with acetone-fixed B. bigemina-infected erythrocytes were selected for purification and further characterization. The MAb were species specific, since they did not cross-react with B. bovis, but they were not stage specific. The purpose of this study was to evaluate the biological activity of B. bigemina-specific MAb in vitro. Three MAb inhibited the multiplication of B. bigemina in vitro as assessed by a lowered percentage of parasitized erythrocytes and by a decreased incorporation of [3H]hypoxanthine. These MAb are now being utilized to purify the correspondent parasite polypeptides, either native or recombinant, in order to test them as subunit immunogens.