A common high molecular weight antigen of Babesia bovis isolates from Mexico

Cattle from an area of Mexico endemic with Babesia bovis infections have a dominant antibody response to a 152 kDa antigen of the Tamaulipas strain of B. bovis. A mAb termed PB/5, showing a specific reactivity to this 152 kDa antigen in Western blots, was identified. The mAb which reacted with the blunt end of B. bovis in an indirect fluorescent antibody test also reacted to a 152 kDa antigen in two other isolates (Nuevo Leon and Yucatan), and a 175 kDa antigen in the Huasteca B. bovis isolate from Mexico. Polyclonal monospecific sera from a calf inoculated with mAb-affinity purified 152 kDa antigen (Tamaulipas strain) identified B. bovis by the indirect fluorescent antibody test and two antigens of B. bovis (65 kDa and 152 kDa) in Western blot. Since the epitope reacting to the mAb PB/5 is conserved, this antigen provides a basis for developing a diagnostic test or an immunogen.