MONOCLONAL-ANTIBODY AGAINST BABESIA-EQUI - CHARACTERIZATION AND POTENTIAL APPLICATION OF ANTIGEN FOR SERODIAGNOSIS

Monoclonal antibody (MAb) BEG3 was produced against Babesia equi paras ites to define a species-specific antigen for diagnostic use. The MAb reacted with single, paired, and Maltese cross forms of B, equi, and n o reaction was observed with this MAb on acetone-fixed Babesia caballi , Babesia ovata, or Babesia microti parasites in the indirect immunofl uorescent antibody test. Confocal laser and immunoelectron microscopic studies showed that the antigen which was recognized by this MAb was located on the surface of B. equi parasites. This MAb recognized a 19- kDa protein of B. equi antigen and did not react with B, caballi antig en or normal horse erythrocytes in immunoblot analysis. This MAb also significantly inhibited the in vitro growth of the B, equi parasite. P reliminary studies using partially purified antigen, which was separat ed by high-pressure liquid chromatography and recognized by the MAb, s uggested that it is a suitable antigen for enzyme-linked immunosorbent assay detection of anti-B. equi antibodies in naturally infected hors e sera.