Kinetic Tracking of Plasmodium falciparum Antigens on Infected Erythrocytes with a Novel Reporter of Protein Insertion and Surface Exposure
Jinfeng Shao, Gunjan Arora, Javier Manzella‐Lapeira, Joseph Brzostowski, Sanjay A. Desai
Abstract
Malaria parasites invade and replicate within red blood cells of their human or animal hosts to avoid immune detection. At the same time, these parasites insert their own proteins into the host membrane to scavenge plasma nutrients, facilitate immune evasion, and perform other essential activities. As there is broad interest in developing vaccines and antimalarial therapies against these surface-exposed antigens, robust methods are needed to examine how and when parasite proteins insert at the host membrane. We therefore developed and used Reporter of Insertion and Surface Exposure (RISE) to track parasite antigen exposure. Using RISE, we followed the time course of membrane insertion for CLAG3, a conserved protein linked to a nutrient uptake channel on infected erythrocytes. We found that CLAG3 insertion occurs at specific parasite stages and that this insertion is required for the formation of the nutrient uptake channel. We also varied the size and charge of the extracellular domain to define constraints on protein insertion at the host membrane. Single-cell imaging revealed that some cells continued to export CLAG3 even with large extracellular loops, suggesting sophisticated strategies used by malaria parasites to control their interactions with host plasma.