Identification of antigens diagnostic for European isolates of Babesia equi by two-dimensional electrophoresis and western blotting.

A lysate of Babesia equi-infected erythrocytes (USDA strain) was separated by two-dimensional electrophoresis and analysed by Western blotting. Nine major antigens or antigen groups with mol. wts. ranging from 43 to 19 kDa were recognized by sera from horses experimentally infected with the USDA strain. Four antigens or antigen groups were also recognized by some or all sera from horses infected with B. caballi or not infected with Babesia spp. Of the remaining five antigens, four were recognized by all sera from field-infected horses from Europe. Thus, four antigens with mol. wts. of 33, 31, 19 and 20 kDa were identified as diagnostic antigens for European isolates of B. equi. None of the antigens diagnostic for European isolates was recognized by sera from field-infected horses from Brazil.