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Structure-Guided Design of a Synthetic Mimic of an Endothelial Protein C Receptor-Binding PfEMP1 Protein.
- Source :
-
MSphere [mSphere] 2021 Jan 06; Vol. 6 (1). Date of Electronic Publication: 2021 Jan 06. - Publication Year :
- 2021
-
Abstract
- Structure-guided vaccine design provides a route to elicit a focused immune response against the most functionally important regions of a pathogen surface. This can be achieved by identifying epitopes for neutralizing antibodies through structural methods and recapitulating these epitopes by grafting their core structural features onto smaller scaffolds. In this study, we conducted a modified version of this protocol. We focused on the PfEMP1 protein family found on the surfaces of erythrocytes infected with Plasmodium falciparum A subset of PfEMP1 proteins bind to endothelial protein C receptor (EPCR), and their expression correlates with development of the symptoms of severe malaria. Structural studies revealed that PfEMP1 molecules present a helix-kinked-helix motif that forms the core of the EPCR-binding site. Using Rosetta-based design, we successfully grafted this motif onto a three-helical bundle scaffold. We show that this synthetic binder interacts with EPCR with nanomolar affinity and adopts the expected structure. We also assessed its ability to bind to antibodies found in immunized animals and in humans from malaria-endemic regions. Finally, we tested the capacity of the synthetic binder to effectively elicit antibodies that prevent EPCR binding and analyzed the degree of cross-reactivity of these antibodies across a diverse repertoire of EPCR-binding PfEMP1 proteins. Despite our synthetic binder adopting the correct structure, we find that it is not as effective as the CIDRĪ± domain on which it is based for inducing adhesion-inhibitory antibodies. This cautions against the rational design of focused immunogens that contain the core features of a ligand-binding site of a protein family, rather than those of a neutralizing antibody epitope. IMPORTANCE Vaccines train our immune systems to generate antibodies which recognize pathogens. Some of these antibodies are highly protective, preventing infection, while others are ineffective. Structure-guided rational approaches allow design of synthetic molecules which contain only the regions of a pathogen required to induce production of protective antibodies. On the surfaces of red blood cells infected by the malaria parasite Plasmodium falciparum are parasite molecules called PfEMP1 proteins. PfEMP1 proteins, which bind to human receptor EPCR, are linked to development of severe malaria. We have designed a synthetic protein on which we grafted the EPCR-binding surface of a PfEMP1 protein. We use this molecule to show which fraction of protective antibodies recognize the EPCR-binding surface and test its effectiveness as a vaccine immunogen.<br /> (Copyright © 2021 Barber et al.)
- Subjects :
- Amino Acid Motifs
Animals
Antibodies, Protozoan immunology
Binding Sites
Cell Adhesion
Endothelial Protein C Receptor immunology
Erythrocytes parasitology
Humans
Malaria, Falciparum drug therapy
Malaria, Falciparum prevention & control
Plasmodium falciparum immunology
Plasmodium falciparum pathogenicity
Protein Binding
Proteins chemistry
Proteins immunology
Rats
Antibodies, Protozoan metabolism
Endothelial Protein C Receptor metabolism
Proteins chemical synthesis
Proteins metabolism
Protozoan Proteins agonists
Protozoan Proteins chemistry
Protozoan Proteins metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 2379-5042
- Volume :
- 6
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- MSphere
- Publication Type :
- Academic Journal
- Accession number :
- 33408232
- Full Text :
- https://doi.org/10.1128/mSphere.01081-20