In vitro cultivation of a Babesia sp. from cattle in South Africa

A South African Babesia sp. of cattle which is as yet unclassified, was continuously cultivated in micro-aerophilous stationary-phase culture. The parasites were resuscitated from a blood stabilate stored in liquid nitrogen. A modified HL-1 medium supplemented with either horse or bovine serum was used. Cultures were initiated in a humidified atmosphere containing 2% O2, 5% CO2 and 93% N2 at 37 degrees C. Parasites were detected on Giemsa-stained smears after 2 d in culture. On day 4, the cultures were split at a ratio of 1:2 (v/v) and transferred into a humidified atmosphere of 5% CO2 in air. Starting from day 6, subcultures were made daily at a ratio of 1:4 (v/v). The percentage of parasitized erythrocytes ranged from 2-5%. Addition of purine bases (hypoxanthine, adenine, adenosine or guanosine) was essential for the continuous propagation of the parasites when bovine, but not horse serum, was used for medium supplementation.