In Vitro Observations on Drug Responsiveness of Babesia bovis and on the Emergence of Drug Resistant Parasites

Four culture lines of Babesia bovis Thai strain were successfully established in this study. The results of the in vitro microtest for their sensitivities to quinuronium sulfate revealed that all the culture lines were similarly drug responsive. The 50% inhibitory concentrations for the four culture lines were found to be within the same range, varying from 1.72x10-6 to 2.43x10-6 g/ml. One resistant line TS-2R selected from the drug-treated culture had an IC50 of 1.71x10-5 g/ml which was 7 times higher than that of its original isolate TS-2