FIG. 4.

Fluorescence-based assay for malarial growth. (A) Cultures of P. falciparum clone D8 were subjected to FACS on a FACScalibur, and data were processed with CellQuest version 3.1 (Becton Dickinson). For growth assays, ring-infected cells were mock treated (green) or incubated with known inhibitors, such as 1 μM quinine (brown), 50 nM artemisinin (blue), and 50 nM mefloquine (pink), for 48 h and then subjected to FACS analysis. Fluorescence associated with the parent strain 3D7 was 1 log lower than that seen with D8 (data not shown). (B) Histogram showing the effect of inhibitors on growth of P. falciparum D8. Untreated or treated fluorescent parasites were FACS counted, and the numbers of fluorescent parasites of untreated cultures were taken to reflect 100% growth.