[Comparative study of assay methods for in vitro antimalarial drug efficacy testing in Plasmodium falciparum]

To compare four assay methods of in vitro antimalarial drug efficacy testing, including WHO microtest, Plasmodial lactate dehydrogenase (pLDH), Histidine-rich protein II (HRP II) and SYBR Green I, so as to determine a stable, simple, rapid, and economic method for monitoring the drug sensitivity of malaria parasites and screening new antimalarial drugs.

WHO microtest, pLDH, HRP II and SYBR Green I were applied to test the drug efficacy of chloroquine, piperaquine and amodiaquine against four Plasmodiumfalciparum reference strains (3D7, FCC, K1 and Dd2), respectively. The consistency of the 50% inhibitory concentration (IC50) values from the four assay methods were analyzed by Friedman tests, Partial correlation analysis, Pearson' s correlation analysis and Bland-Altman plots.

With the initial parasitemia ranged from 0.5% to 1%, there were no statistically significant differences (P> 0.05) among the IC50 values obtained by the four assay methods, which were correlated well (both P< 0.001). WHO microtest was highly labor-intensive, time-consuming and subjective; although HRP II was more sensitive than pLDH and SYBR Green I, which was more expensive; SYBR Green I was a simple, rapid and economic assay method.

SYBR Green I, as a simple and cost-effective assay method, is suitable for high-throughput malaria drug sensitivity monitoring and research of new antimalarial drug screening.