Antigenic variation in Babesia bovis: how similar is it to that in Plasmodium falciparum?

Despite significant differences in some aspects of their life-cycles, the Apicomplexan parasites Babesia bovis and Plasmodium falciparum share many parallels. Significant among these are participation in rapid, clonal antigenic variation, and cyto-adherence and sequestration in the deep vasculature. Antigenic variation has long been thought to be primarily a mechanism of escape from antibody-mediated mechanisms of the host's immune system. In each species, the components demonstrated to participate in antigenic variation are parasite-derived proteins expressed on the infected erythrocyte's surface. Recently, the malarial component PfEMP1 has been found to be a multifunctional protein that is not only subject to antigenic variation, but also participates in cyto-adherence and rosetting (adhesion to uninfected erythrocytes). In the present review, the antigens elaborated on the surface of an erythrocyte infected with B. bovis, for immune evasion via antigenic variation, are described, and compared and contrasted with those from P. falciparum. The significance of the similarities between B. bovis and P. falciparum, and the potential for contributions to be made to our understanding of malaria through the study of babesiosis are discussed.