Malarial proteins probed in new study
A recent paper by Associate Professor John Vakonakis provides insight into the damaging changes to red blood cells that are characteristic of malarial infection.
Immunofluorescent 3D reconstruction of fixed infected red blood cells with malarial parasites expressing PHIST protein tagged with GFP
Malaria is responsible for almost one million deaths each year, the majority among small children. Most of these deaths are caused by Plasmodium falciparum. This parasite species is particularly deadly because of the unique modifications it induces in the host erythrocyte upon infection.
One such change is the development of dense protrusions on the infected red blood cell surface, known as knobs. Knobs serve as platforms for the parasite adhesion receptor family PfEMP1 which can attach to ligands on the endothelial lining of blood vessels, other erythrocytes, and the placenta. The blood vessel obstruction and tissue damage that follow are major factors contributing to severe malaria and lethality.
Professor Vakonakis and colleagues in Switzerland have explored some of the proteins associated with knobs. In their paper (1), they describe the structure of a protein from the parasitic PHIST family, implicated in host-parasite interactions, and provide evidence for the protein's involvement in formation of knobs on the infected erythrocyte surface.
The group found that the PHIST protein with the highest affinity for PfEMP1 is the one that temporally and spatially localizes with PfEMP1 all the way to knobs on the infected red blood cell surface.
Their findings complement another paper recently published in FASEB J (2) in which this specific PHIST protein was deleted, resulting in a reduction in pathogenic cytoadherence of around 50%.
The research provides valuable information about a protein associated with this important aspect of malarial pathology.
1. A Plasmodium falciparum PHIST protein binds the virulence factor PfEMP1 and comigrates to knobs on the host cell surface. Oberli, A, Slater, LM, Cutts, E, Brand, F, Mundwiler-Pachlatko, E, Rusch, S, Masik, MFG, Erat, MC, Beck, HP and Vakonakis, I. Faseb J (2014) doi: 10.1096/fj.14-256057
2. A lysine-rich membrane-associated PHISTb protein involved in alteration of the cytoadhesive properties of Plasmodium falciparum-infected red blood cells. Proellocks, NI, Herrmann, S, Buckingham, DW, Hanssen, E, Hodges, EK, Elsworth, B, Morahan, BJ, Coppel, RL and Cooke BM. Faseb J (2014) Jul;28(7):3103-3113