The genes encoding the predicted domains I and II of BmAMA1 and transmembrane regions 2 and 3 of BmRON2 were expressed in Escherichia coli. Serum from a hamster immunized with B. microti recognized the rBmAMA1, but there was no reaction with rBmRON2 in Western blot analysis. Sera from mice immunized with rBmAMA1 and rBmRON2 detect distinct band in B. microti lysate. The hamsters immunized with rBmAMA1+rBmRON2 exhibited limited protection against B. microti challenge infection.