Discovering the targets of drugs that stop malaria parasites invading red blood cells

Malaria caused by the blood-stage of Plasmodium falciparum, remains a major global health problem with about 40 per cent of the world’s population at risk of infection. Although there have been major reductions in disease impact over the last 10 years due to increased malaria control, this downward trajectory has recently stalled.

Of particular concern is the spread of multi-drug resistant parasites in regions of Asia, including to artemisinin combination therapies, the current frontline treatments. This emphasizes the critical need to discover novel drug targets with different and known mechanisms of action (MoA) to produce highly potent treatments refractory to resistance.

After the invasive merozoite parasite stage invades a red blood cell (RBC), the parasite grows and replicates to yield ~20 new merozoites that egress from the old RBC to infect new cells. This exponential amplification of infected RBCs results in symptomatic malaria and as such merozoites are an ideal therapeutic target since any new drug or vaccine that could block merozoite invasion would dramatically reduce the parasite load.

This project will involve discovering the MoA of several invasion inhibiting drugs identified in a library of parasite killing compounds called the MMV Malaria Box. Bioluminescent parasites treated with the MMV compounds will be assayed to discover which step in the complex egress and RBC invasion process is being blocked. Live cell imaging of invading merozoites will be further performed to validate which invasion step is being affected by the MMV compounds. Finally, parasites will be repeatedly treated with the MMV compounds to attempt to select for genetic resistance in genes for the target proteins of the drugs. If time permits target gene mutations will be identified through genome sequencing.

Laboratory techniques learned will include tissue culturing, parasites growth experiments, assay development and fluorescence microscopy.