falciparum were reported to possess an apicoplast which contains the methylerythritol phosphate (MEP) pathway inhibitable by fosmidomycin, suggesting that the pathway could serve as a drug target for screening new drugs. However, it remains unknown in B. orientalis. Primers were designed according to the seven MEP pathway genes of Babesia microti and Babesia bovis. The genes were cloned, sequenced and BoDXR in B. orientalis. Fosmidomycin and geranylgeraniol were used for inhibition assay and rescue assay, respectively, in the in vitro cultivation of B. orientalis. The seven enzyme genes of the B. orientalis MEP pathway (DXS, DXR, IspD, IspE, IspF, IspG and IspH) were cloned and sequenced, with a full length of 2094, 1554, 1344, 1521, 654, 1932 and 1056 bp, respectively. BoDXS and BoDXR were