Identification of MMV Malaria Box inhibitors of Plasmodium falciparum Early-Stage Gametocytes, Using a Luciferase-Based High-Throughput Assay

View/ Open
Author(s)
Lucantoni, Leonardo
Duffy, Sandra
Adjalley, Sophie H
Fidock, David A
Avery, Vicky M
Year published
2013
Metadata
Show full item recordAbstract
The design of new antimalarial combinations to treat Plasmodium falciparum infections requires drugs that, in addition to resolving disease symptoms caused by asexual blood stage parasites, can also interrupt transmission to the mosquito vector. Gametocytes, which are essential for transmission, develop as sexual blood stage parasites in the human host over 8-12 days and are the most accessible developmental stage for transmission-blocking drugs. Considerable effort is currently being devoted to identifying compounds active against mature gametocytes. However, investigations on the drug sensitivity of developing gametocytes, ...
View more >The design of new antimalarial combinations to treat Plasmodium falciparum infections requires drugs that, in addition to resolving disease symptoms caused by asexual blood stage parasites, can also interrupt transmission to the mosquito vector. Gametocytes, which are essential for transmission, develop as sexual blood stage parasites in the human host over 8-12 days and are the most accessible developmental stage for transmission-blocking drugs. Considerable effort is currently being devoted to identifying compounds active against mature gametocytes. However, investigations on the drug sensitivity of developing gametocytes, as well as screening methods for identifying inhibitors of early gametocytogenesis, remain scarce. We have developed a luciferase-based high-throughput screening (HTS) assay using tightly synchronous stage I - III gametocytes from a recombinant P. falciparum line expressing GFP-luciferase. The assay has been used to evaluate the early stage gametocytocidal activity of the MMV Malaria Box, a collection of 400 compounds with known antimalarial (asexual blood stage) activity. Screening this collection against early-stage (I-III) gametocytes yielded 64 gametocytocidal compounds with IC50 values below 2.5 卮 This assay is reproducible and suitable for the screening of large compound libraries, with an average % coefficient of variance (CV) = 5%, an average signal to noise ratio (S:N) > 30 and a Z' ~0.8. Our findings highlight the need for screening efforts directed specifically against early gametocytogenesis, and indicate the importance of experimental verification of early stage gametocytocidal activity in the development of new antimalarial candidates for combination therapy.
View less >
View more >The design of new antimalarial combinations to treat Plasmodium falciparum infections requires drugs that, in addition to resolving disease symptoms caused by asexual blood stage parasites, can also interrupt transmission to the mosquito vector. Gametocytes, which are essential for transmission, develop as sexual blood stage parasites in the human host over 8-12 days and are the most accessible developmental stage for transmission-blocking drugs. Considerable effort is currently being devoted to identifying compounds active against mature gametocytes. However, investigations on the drug sensitivity of developing gametocytes, as well as screening methods for identifying inhibitors of early gametocytogenesis, remain scarce. We have developed a luciferase-based high-throughput screening (HTS) assay using tightly synchronous stage I - III gametocytes from a recombinant P. falciparum line expressing GFP-luciferase. The assay has been used to evaluate the early stage gametocytocidal activity of the MMV Malaria Box, a collection of 400 compounds with known antimalarial (asexual blood stage) activity. Screening this collection against early-stage (I-III) gametocytes yielded 64 gametocytocidal compounds with IC50 values below 2.5 卮 This assay is reproducible and suitable for the screening of large compound libraries, with an average % coefficient of variance (CV) = 5%, an average signal to noise ratio (S:N) > 30 and a Z' ~0.8. Our findings highlight the need for screening efforts directed specifically against early gametocytogenesis, and indicate the importance of experimental verification of early stage gametocytocidal activity in the development of new antimalarial candidates for combination therapy.
View less >
Journal Title
Antimicrobial agents and Chemotherapy
Volume
57
Issue
12
Copyright Statement
© 2013 American Society for Microbiology. This is the author-manuscript version of this paper. Reproduced in accordance with the copyright policy of the publisher. Please refer to the journal's website for access to the definitive, published version.
Subject
Microbiology
Infectious agents
Medical microbiology
Pharmacology and pharmaceutical sciences