Sequestration of Plasmodium falciparum-infected erythrocytes in host blood vessels is a key triggering event in the pathogenesis of severe childhood malaria, which is responsible for about one million deaths every year 1 . Sequestration is mediated by specific interactions between members of the P. falciparum erythrocyte membrane protein 1 (PfEMP1) family and receptors on the endothelial lining 2 . Severe malaria is associated with expression of specific PfEMP1 subtypes containing domain cassettes (DC) 8 and 13 3 , but the endothelial receptor for parasites expressing these proteins was unknown 4,5 . Here, we identify endothelial protein C receptor (EPCR), which mediates cytoprotective effects of activated protein C 6 , as the endothelial receptor for DC8 and DC13 PfEMP1. We show that EPCR binding is mediated through the N-terminal cysteine-rich interdomain region (CIDRα1) of DC8 and group A PfEMP1 subfamilies and that CIDRα1 interferes with protein C binding to EPCR. This PfEMP1 adhesive property links P. falciparum Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:http://www.nature.com/authors/editorial_policies/license.html#terms † Correspondence to: thomasl@sund.ku.dk and lturner@sund.ku.dk. * These authors contributed equally to the work.Supplementary Information is linked to the online version of the paper at www.nature.com/nature.Author Contributions: LT, TL, JDS and AJB produced recombinant proteins; JF performed the protein array experiments; SSB, CWW, JEVP, MAN, MA, JSJ and JDS performed the work with malaria parasites; PM, JL and TGT organized clinical work and processed clinical samples; MKK performed the surface plasmon resonance studies; LT performed the ELISA studies. The study was conceived and planned by LT, TL and TGT. The manuscript was written by TL, TGT, LT, JDS, and MH. All authors read and commented on the manuscript. LT and TL contributed equally to the work.Author Informaton: Reprints and permissions information is available at www.nature.com/reprints.The authors have no competing financial interests. To identify the DC8-PfEMP1 receptor, we produced a full-length DC8-containing PfEMP1 using the var gene IT4var20 from the FCR3/IT4 parasite. This 288 kDa His-tagged recombinant protein (rIT4VAR20) was screened against an array of 2505 full-length human plasma membrane proteins expressed on HEK293 cells (Table S1) S3) and all found to bind brain-derived endothelial cells via EPCR (Table S3). Previous work has shown that DC8-and DC13-variants selected on brain endothelial cells also bind to non-brain microvascular endothelial cells from heart and lung 4,5 . Binding of the FCR3 IT4VAR19b parasite line (described in 4 ) to brain, heart, lung and bone marrow endothelial cells was evaluated and found to be mediated by EPCR (Table S3). Altogether, these results demonstrate cytoadhesion of DC8 PfEMP1 expressing parasites via EPCR on endothelial cells of diverse tissu...

SummaryThe PfEMP1 family of surface proteins is central for Plasmodium falciparum virulence and must retain the ability to bind to host receptors while also diversifying to aid immune evasion. The interaction between CIDRα1 domains of PfEMP1 and endothelial protein C receptor (EPCR) is associated with severe childhood malaria. We combine crystal structures of CIDRα1:EPCR complexes with analysis of 885 CIDRα1 sequences, showing that the EPCR-binding surfaces of CIDRα1 domains are conserved in shape and bonding potential, despite dramatic sequence diversity. Additionally, these domains mimic features of the natural EPCR ligand and can block this ligand interaction. Using peptides corresponding to the EPCR-binding region, antibodies can be purified from individuals in malaria-endemic regions that block EPCR binding of diverse CIDRα1 variants. This highlights the extent to which such a surface protein family can diversify while maintaining ligand-binding capacity and identifies features that should be mimicked in immunogens to prevent EPCR binding.

SummaryCerebral malaria is a deadly outcome of infection by Plasmodium falciparum, occurring when parasite-infected erythrocytes accumulate in the brain. These erythrocytes display parasite proteins of the PfEMP1 family that bind various endothelial receptors. Despite the importance of cerebral malaria, a binding phenotype linked to its symptoms has not been identified. Here, we used structural biology to determine how a group of PfEMP1 proteins interacts with intercellular adhesion molecule 1 (ICAM-1), allowing us to predict binders from a specific sequence motif alone. Analysis of multiple Plasmodium falciparum genomes showed that ICAM-1-binding PfEMP1s also interact with endothelial protein C receptor (EPCR), allowing infected erythrocytes to synergistically bind both receptors. Expression of these PfEMP1s, predicted to bind both ICAM-1 and EPCR, is associated with increased risk of developing cerebral malaria. This study therefore reveals an important PfEMP1-binding phenotype that could be targeted as part of a strategy to prevent cerebral malaria.