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Fig. 5 | Malaria Journal

Fig. 5

From: A simple monochromatic flow cytometric assay for assessment of intraerythrocytic development of Plasmodium falciparum

Fig. 5

Application of VSG-based flow cytometry in synchrony assessment and anti-malarial drug assay. a Microscopic images of P. falciparum-infected erythrocytes derived from non-synchronized and synchronized cultures and stained with Giemsa dye. b Flow cytometric profiles of VSG+ cells are displayed according to FSC-A (X-axis) and SSC-A (Y-axis) in contour plots. Histograms of FSC-A and SSC-A are shown at the top and left side of the contour plots, respectively. There were at least three distinct populations observed in the non-synchronized culture (left panel), as follows: (1) cells having small size with various granularity; (2) cells having a relatively large size with high granularity; and, (3) cells having a relatively larger size with low granularity. There were two populations observed in the synchronized culture (right panel), as follows: (1) minor population with SSC-A higher than 160 K, and (2) major population with SSC-A lower than 160 K. c Graph of coefficient of variation of FSC-A and SSC-A. Dots represent three independent experiments. dP. falciparum-infected erythrocytes were treated with anti-malarial drug dihydroartemisinin (DHA) and subjected to VSG-based flow cytometric analysis. Synchronized ring forms were prepared. e Dose-dependent effect of DHA treatment on growth inhibition of P. falciparum. The infected erythrocytes were treated with 350, 700, and 1400 nM of DHA for 24 h and subjected to VSG-based flow cytometric analysis. f Time-dependent effect of DHA treatment on growth inhibition of P. falciparum. After 6-h treatment with 700 nM DHA, the infected erythrocytes were cultured in MCM without DHA and collected at 12, 24, 36, 48, and 60 h for VSG-based flow cytometric analysis. The number of VSG+ cells in DMSO treatment was set as the control for each time point. The percentage of VSG+ cells in DHA treatment was compared to that observed in the control (Y-axis). X-axis indicates time of culture. Data represent mean ± SD of three independent experiments. FSC-A, forward scatter-area; SSC-A, side scatter-area; NS, non-synchronized culture; S, synchronized culture; CV, coefficient of variation

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