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...

In Plasmodium falciparum–endemic areas, pregnancy-associated malaria (PAM) is an important health problem. The condition is precipitated by accumulation of parasite-infected erythrocytes (IEs) in the placenta, and this process is mediated by parasite-encoded variant surface antigens (VSA) binding to chondroitin sulfate A (CSA). Parasites causing PAM express unique VSA types, VSAPAM, which can be serologically classified as sex specific and parity dependent. It is sex specific because men from malaria-endemic areas do not develop VSAPAM antibodies; it is parity dependent because women acquire anti-VSAPAM immunoglobulin (Ig) G as a function of parity. Previously, it was shown that transcription of var2csa is up-regulated in placental parasites and parasites selected for CSA binding. Here, we show the following: (a) that VAR2CSA is expressed on the surface of CSA-selected IEs; (b) that VAR2CSA is recognized by endemic plasma in a sex-specific and parity-dependent manner; (c) that high anti-VAR2CSA IgG levels can be found in pregnant women from both West and East Africa; and (d) that women with high plasma levels of anti-VAR2CSA IgG give birth to markedly heavier babies and have a much lower risk of delivering low birth weight children than women with low levels.

The clinical outcome of Plasmodium falciparum infections ranges from asymptomatic parasitemia to severe malaria syndromes associated with high mortality. The virulence of P. falciparum infections is associated with the type of P. falciparum erythrocyte membrane protein 1 (PfEMP1) expressed on the surface of infected erythrocytes to anchor these to the vascular lining. Although var2csa, the var gene encoding the PfEMP1 associated with placental malaria, was discovered in 2003, the identification of the var/PfEMP1 variants associated with severe malaria in children has remained elusive. To identify var/PfEMP1 variants associated with severe disease outcome, we compared var transcript levels in parasites from 88 children with severe malaria and 40 children admitted to the hospital with uncomplicated malaria. Transcript analysis was performed by RT-quantitative PCR using a set of 42 primer pairs amplifying var subtype-specific loci covering most var/ PfEMP1 subtypes. In addition, we characterized the near-fulllength sequence of the most prominently expressed var genes in three patients diagnosed with severe anemia and/or cerebral malaria. The combined analysis showed that severe malaria syndromes, including severe anemia and cerebral malaria, are associated with high transcript levels of PfEMP1 domain cassette 8-encoding var genes. Transcript levels of group A var genes, including genes encoding domain cassette 13, were also significantly higher in patients with severe syndromes compared with those with uncomplicated malaria. This study specifies the var/PfEMP1 types expressed in severe malaria in children, and thereby provides unique targets for future efforts to prevent and treat severe malaria infections.