Live Imaging Studies of Invasion Phenotypes of Erythrocytes by P. Falciparum

Abstract

Severe malaria by Plasmodium falciparum is a leading cause of death in many developing countries. In the blood stage of the disease, merozoite invasion of erythrocytes is a repetitive intraerythrocytic cycle which takes place over a ∼ 48-hour period. Infection of healthy blood cells occurs only within a few minutes after parasite egression, and is a critical point in the progression of the disease1. Furthermore, this process involving complex receptor-ligand binding processes. To understand specific receptor-ligand interactions, we investigate morphology and kinetics during P. Falciparum invasion with various antibodies filmed by video microscopy, building on [2]. We quantify invasion phenotypes such as efficiency, timescales and pathogen/host adhesion strength. This study aims to understand mechanism of malaria invasion and aid the design of drugs or vaccines that could block this stage of the parasite's life cycle.In parallel to static cultures we develop microfluidic devices to achieve high throughput of merozosites under controlled flows. Infected red blood cells (IRBCs) are delivered into a channel containing cage-like “nests”, which block these relatively stiff cells. The IRBS then continue maturation, delivering a stream of parasites. Non infected RBCs are delivered from another input, and pass unhindered through the nests, to a long serpentine channel where they co-flow with the egressed parasites. This setup allows the observation of parasite invasion in flow, to identify the changes in invasion under variant flow and with increased throughput than static cultures.