title: Immunogenicity of the Plasmodium falciparum PfEMP1-VarO Adhesin: Induction of Surface-Reactive and Rosette-Disrupting Antibodies to VarO Infected Erythrocytes.
abstract: Adhesion of Plasmodium falciparum-infected red blood cells (iRBC) to human erythrocytes (i.e. rosetting) is associated with severe malaria. Rosetting results from interactions between a subset of variant PfEMP1 (Plasmodium falciparum erythrocyte membrane protein 1) adhesins and specific erythrocyte receptors. Interfering with such interactions is considered a promising intervention against severe malaria. To evaluate the feasibility of a vaccine strategy targetting rosetting, we have used here the Palo Alto 89F5 VarO rosetting model. PfEMP1-VarO consists of five Duffy-Binding Like domains (DBL1-5) and one Cysteine-rich Interdomain Region (CIDR1). The binding domain has been mapped to DBL1 and the ABO blood group was identified as the erythrocyte receptor. Here, we study the immunogenicity of all six recombinant PfEMP1-VarO domains and the DBL1- CIDR1 Head domain in BALB/c and outbred OF1 mice. Five readouts of antibody responses are explored: ELISA titres on the recombinant antigen, VarO-iRBC immunoblot reactivity, VarO-iRBC surface-reactivity, capacity to disrupt VarO rosettes and the capacity to prevent VarO rosette formation. For three domains, we explore influence of the expression system on antigenicity and immunogenicity. We show that correctly folded PfEMP1 domains elicit high antibody titres and induce a homogeneous response in outbred and BALB/c mice after three injections. High levels of rosette-disrupting and rosette-preventing antibodies are induced by DBL1 and the Head domain. Reduced-alkylated or denatured proteins fail to induce surface-reacting and rosette-disrupting antibodies, indicating that surface epitopes are conformational. We also report limited cross-reactivity between some PfEMP1 VarO domains. These results highlight the high immunogenicity of the individual domains in outbred animals and provide a strong basis for a rational vaccination strategy targeting rosetting.
authors.affiliation: Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, Paris, France; Centre National de la Recherche Scientifique, Unité de recherche associée 2581, Paris, France.
authors.forename: Micheline
authors.initials: M
authors.lastname: Guillotte
authors.affiliation: Institut Pasteur, Unité d'Immunologie Structurale, Paris, France; Centre National de la Recherche Scientifique, Unité de recherche associée 2185, Paris, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Juillerat
authors.affiliation: Institut Pasteur, Unité d'Immunologie Structurale, Paris, France; Centre National de la Recherche Scientifique, Unité de recherche associée 2185, Paris, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Igonet
authors.affiliation: Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, Paris, France; Institut Pasteur, Unité d'Immunologie Structurale, Paris, France.
authors.forename: Audrey
authors.initials: A
authors.lastname: Hessel
authors.affiliation: Institut Pasteur, Plate-forme de Protéines recombinantes (PFPR), Paris, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Petres
authors.affiliation: Institut Pasteur, Plate-forme de Protéines recombinantes (PFPR), Paris, France.
authors.forename: Elodie
authors.initials: E
authors.lastname: Crublet
authors.affiliation: Bordeaux Biothèques Santé, Groupe hospitalier Pellegrin, Centre Hospitalier Universitaire de Bordeaux - Bordeaux, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Le Scanf
authors.affiliation: Institut Pasteur, Unité d'Immunologie Structurale, Paris, France; Centre National de la Recherche Scientifique, Unité de recherche associée 2185, Paris, France.
authors.forename: Anita
authors.initials: A
authors.lastname: Lewit-Bentley
authors.affiliation: Institut Pasteur, Unité d'Immunologie Structurale, Paris, France; Centre National de la Recherche Scientifique, Unité de recherche associée 2185, Paris, France.
authors.forename: Graham A
authors.initials: GA
authors.lastname: Bentley
authors.affiliation: Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, Paris, France; Centre National de la Recherche Scientifique, Unité de recherche associée 2581, Paris, France.
authors.forename: Inès
authors.initials: I
authors.lastname: Vigan-Womas
authors.affiliation: Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, Paris, France; Centre National de la Recherche Scientifique, Unité de recherche associée 2581, Paris, France.
authors.forename: Odile
authors.initials: O
authors.lastname: Mercereau-Puijalon
mesh_terms: D018829:Adhesins, Bacterial / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D000953:Antigens, Protozoan / Q000737:chemistry / Q000235:genetics; D003429:Cross Reactions; D000939:Epitopes / Q000737:chemistry / Q000235:genetics; D004912:Erythrocytes / Q000469:parasitology; D005260:Female; D006801:Humans; D017780:Malaria Vaccines / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D016778:Malaria, Falciparum / Q000276:immunology / Q000469:parasitology / Q000517:prevention & control; D051379:Mice; D008807:Mice, Inbred BALB C; D010963:Plasmodium falciparum / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D012397:Rosette Formation
chemical_list: D018829:Adhesins, Bacterial; D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D000939:Epitopes; D017780:Malaria Vaccines; D015800:Protozoan Proteins; D011994:Recombinant Proteins; C085731:erythrocyte membrane protein 1, Plasmodium falciparum