In vitro culture of Babesia bovis in a bovine serum-free culture medium supplemented with insulin, transferrin, and selenite.

Bovine serum is an important factor for the optimal growth of Babesia bovis in vitro. This protozoan can be cultured in M-199 with Earle's salts medium (M-199) supplemented with 40% bovine serum (BS). In the present study, four media were assessed along with the control medium M-199. The effect on the proliferation of B. bovis in vitro was tested when these media were combined with insulin (Ins), transferrin (Trans) and selenite (Sel) in the absence of bovine serum. Treatment with Advanced DMEM/F12 medium (A-DMEM/F12) achieved the highest percentage of parasitized erythrocytes (PPE), reaching a maximum value of 9.59%. A-DMEM/F12 medium supplemented with a mixture of Ins (2000 mg/L), Trans (1100 mg/L), and Sel (1.34 mg/L) allowed for the adaptation and proliferation of B. bovis without bovine serum, showed a constant increase in PPE, and reached a maximum value of 9.7% during seven cycles of in vitro culture. It was concluded that continuous proliferation of B. bovis in vitro could be achieved using A-DMEM/F12 medium supplemented with Ins-Trans-Sel, without bovine serum. After adaptation for proliferation in serum-free medium, the B. bovis strain of parasites could have future use in the study of this economically important protozoan species that affects cattle.