Cloning of in vitro propagated Babesia bigemina.

The original Babesia bigemina culture conditions were modified with regard to infected bovine erythrocyte concentration and atmospheric environment. A procedure was designed which would yield a homogeneous parasite population, beginning with a single infected erythrocyte. Calculated dilutions were made in 96-well tissue culture plates to approach one infected erythrocyte per four wells. Growth of parasites in wells was detected between 16 and 28 days after cultures were initiated. Clones were transferred to 24-well tissue culture plates for regular maintenance. Three primary clones were selected for additional recloning. The probability that the parasites detected in one well are the progeny of a single infected erythrocyte approaches 0.99 for tertiary clones.