title: Surface co-expression of two different PfEMP1 antigens on single plasmodium falciparum-infected erythrocytes facilitates binding to ICAM1 and PECAM1.
abstract: The Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) antigens play a major role in cytoadhesion of infected erythrocytes (IE), antigenic variation, and immunity to malaria. The current consensus on control of variant surface antigen expression is that only one PfEMP1 encoded by one var gene is expressed per cell at a time. We measured var mRNA transcript levels by real-time Q-PCR, analysed var gene transcripts by single-cell FISH and directly compared these with PfEMP1 antigen surface expression and cytoadhesion in three different antibody-selected P. falciparum 3D7 sub-lines using live confocal microscopy, flow cytometry and in vitro adhesion assays. We found that one selected parasite sub-line simultaneously expressed two different var genes as surface antigens, on single IE. Importantly, and of physiological relevance to adhesion and malaria pathogenesis, this parasite sub-line was found to bind both CD31/PECAM1 and CD54/ICAM1 and to adhere twice as efficiently to human endothelial cells, compared to infected cells having only one PfEMP1 variant on the surface. These new results on PfEMP1 antigen expression indicate that a re-evaluation of the molecular mechanisms involved in P. falciparum adhesion and of the accepted paradigm of absolutely mutually exclusive var gene transcription is required.
authors.affiliation: Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, Faculty of Health Sciences, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
authors.forename: Louise
authors.initials: L
authors.lastname: Joergensen
authors.forename: Dominique C
authors.initials: DC
authors.lastname: Bengtsson
authors.forename: Anja
authors.initials: A
authors.lastname: Bengtsson
authors.forename: Elena
authors.initials: E
authors.lastname: Ronander
authors.forename: Sanne S
authors.initials: SS
authors.lastname: Berger
authors.forename: Louise
authors.initials: L
authors.lastname: Turner
authors.forename: Michael B
authors.initials: MB
authors.lastname: Dalgaard
authors.forename: Gerald K K
authors.initials: GK
authors.lastname: Cham
authors.forename: Michala E
authors.initials: ME
authors.lastname: Victor
authors.forename: Thomas
authors.initials: T
authors.lastname: Lavstsen
authors.forename: Thor G
authors.initials: TG
authors.lastname: Theander
authors.forename: David E
authors.initials: DE
authors.lastname: Arnot
authors.forename: Anja T R
authors.initials: AT
authors.lastname: Jensen
mesh_terms: D000940:Antigenic Variation; D000954:Antigens, Surface / Q000378:metabolism; D015152:Blotting, Northern; D015153:Blotting, Western; D002448:Cell Adhesion; D002465:Cell Movement; D004797:Enzyme-Linked Immunosorbent Assay; D004912:Erythrocytes / Q000378:metabolism* / Q000469:parasitology*; D005434:Flow Cytometry; D006801:Humans; D007124:Immunoenzyme Techniques; D017404:In Situ Hybridization, Fluorescence; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism*; D016778:Malaria, Falciparum / Q000235:genetics / Q000378:metabolism* / Q000469:parasitology; D010963:Plasmodium falciparum / Q000235:genetics / Q000472:pathogenicity*; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism*; D015800:Protozoan Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic
chemical_list: D000954:Antigens, Surface; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D015800:Protozoan Proteins; D012333:RNA, Messenger; C085731:erythrocyte membrane protein 1, Plasmodium falciparum; D018799:Intercellular Adhesion Molecule-1
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