A combination of new screening assays for prioritization of transmission-blocking antimalarials reveals distinct dynamics of marketed and experimental drugs
SourceJournal of Antimicrobial Chemotherapy, 70, 5, (2015), pp. 1357-1366
Article / Letter to editor
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Journal of Antimicrobial Chemotherapy
SubjectRadboudumc 4: lnfectious Diseases and Global Health RIHS: Radboud Institute for Health Sciences; Radboudumc 4: lnfectious Diseases and Global Health RIMLS: Radboud Institute for Molecular Life Sciences
OBJECTIVES: The development of drugs to reduce malaria transmission is an important part of malaria eradication plans. We set out to develop and validate a combination of new screening assays for prioritization of transmission-blocking molecules. METHODS: We developed high-throughput assays for screening compounds against gametocytes, the parasite stages responsible for onward transmission to mosquitoes. An existing gametocyte parasitic lactate dehydrogenase (pLDH) assay was adapted for use in 384-well plates, and a novel homogeneous immunoassay to monitor the functional transition of female gametocytes into gametes was developed. A collection of 48 marketed and experimental antimalarials was screened and subsequently tested for impact on sporogony in Anopheles mosquitoes, to directly quantify the transmission-blocking properties of antimalarials in relation to their effects on gametocyte pLDH activity or gametogenesis. RESULTS AND CONCLUSIONS: The novel screening assays revealed distinct stage-specific kinetics and dynamics of drug effects. Peroxides showed the most potent transmission-blocking effects, with an intermediate speed of action and IC50 values that were 20-40-fold higher than the IC50s against the asexual stages causing clinical malaria. Finally, the novel synthetic peroxide OZ439 appeared to be a promising drug candidate as it exerted gametocytocidal and transmission-blocking effects at clinically relevant concentrations.
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