The Bd37 is an erythrocyte binding protein anchored at the surface of the parasite Babesia divergens. B. divergens is an Apicomplexa parasite, mostly of veterinary importance but able to infect humans after tick-bites. The lab model of bovine and human babesiosis is provided by the gerbils Meriones unguiculatus infected by Babesia divergens.
Recombinant hydrophobic Bd37 is able to induce complete protective immune response when mixed with saponin, in contrast to hydrophilic Bd37 which only induce non-protective antibodies.