The Influence of Sub-Unit Composition and Expression System on the Functional Antibody Response in the Development of a VAR2CSA Based Plasmodium falciparum Placental Malaria Vaccine.
The disease caused by Plasmodium falciparum (Pf) involves different clinical manifestations that, cumulatively, kill hundreds of thousands every year. Placental malaria (PM) is one such manifestation in which Pf infected erythrocytes (IE) bind to chondroitin sulphate A (CSA) through expression of VAR2CSA, a parasite-derived antigen. Protection against PM is mediated by antibodies that inhibit binding of IE in the placental intervillous space. VAR2CSA is a large antigen incompatible with large scale recombinant protein expression. Vaccines based on sub-units encompassing the functionally constrained receptor-binding domains may, theoretically, circumvent polymorphisms, reduce the risk of escape-mutants and induce cross-reactive antibodies. However, the sub-unit composition and small differences in the borders, may lead to exposure of novel immuno-dominant antibody epitopes that lead to non-functional antibodies, and furthermore influence the folding, stability and yield of expression. Candidate antigens from the pre-clinical development expressed in High-Five insect cells using the baculovirus expression vector system were transitioned into the Drosophila Schneider-2 cell (S2) expression-system compliant with clinical development. The functional capacity of antibodies against antigens expressed in High-Five cells or in S2 cells was equivalent. This enabled an extensive down-selection of S2 insect cell-expressed antigens primarily encompassing the minimal CSA-binding region of VAR2CSA. In general, we found differential potency of inhibitory antibodies against antigens with the same borders but of different var2csa sequences. Likewise, we found that subtle size differences in antigens of the same sequence gave varying levels of inhibitory antibodies. The study shows that induction of a functional response against recombinant subunits of the VAR2CSA antigen is unpredictable, demonstrating the need for large-scale screening in order to identify antigens that induce a broadly strain-transcending antibody response.
Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Science, University of Copenhagen, and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
Morten A
MA
Nielsen
Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Science, University of Copenhagen, and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
Mafalda
M
Resende
ExpreS2ion Biotechnologies, SCION-DTU Science Park, Hørsholm, Denmark.
Willem A
WA
de Jongh
Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Science, University of Copenhagen, and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
Sisse B
SB
Ditlev
Eberhard Karls Universität Tübingen, Institut für Tropenmedizin, Tübingen, Germany, and Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon.
Benjamin
B
Mordmüller
European Vaccine Initiative, Universitäts Klinikum Heidelberg, Heidelberg, Germany.
Sophie
S
Houard
Institut de Recherche pour le Développement, UMR216 Mère et enfant face aux infections tropicales, Paris, France; PRES Sorbonne Paris Cité, Université Paris Descartes, Paris, France.
Nicaise Tuikue
NT
Ndam
Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Science, University of Copenhagen, and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
Mette Ø
MØ
Agerbæk
Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Science, University of Copenhagen, and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
Mette
M
Hamborg
Faculté des Sciences de la Santé de l'Université d'Abomey-Calavi, Centre d'étude et de recherche sur le paludisme associé à la grossesse et à l'enfance, Cotonou, Bénin.
Achille
A
Massougbodji
Faculté des Sciences de la Santé de l'Université d'Abomey-Calavi, Centre d'étude et de recherche sur le paludisme associé à la grossesse et à l'enfance, Cotonou, Bénin.
Saddou
S
Issifou
ExpreS2ion Biotechnologies, SCION-DTU Science Park, Hørsholm, Denmark.
Anette
A
Strøbæk
ExpreS2ion Biotechnologies, SCION-DTU Science Park, Hørsholm, Denmark.
Lars
L
Poulsen
European Vaccine Initiative, Universitäts Klinikum Heidelberg, Heidelberg, Germany.
Odile
O
Leroy
Eberhard Karls Universität Tübingen, Institut für Tropenmedizin, Tübingen, Germany, and Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon.
Peter G
PG
Kremsner
Institut de Recherche pour le Développement, UMR216 Mère et enfant face aux infections tropicales, Paris, France; PRES Sorbonne Paris Cité, Université Paris Descartes, Paris, France; Faculté des Sciences de la Santé de l'Université d'Abomey-Calavi, Centre d'étude et de recherche sur le paludisme associé à la grossesse et à l'enfance, Cotonou, Bénin.
Jean-Philippe
JP
Chippaux
Institut de Recherche pour le Développement, UMR216 Mère et enfant face aux infections tropicales, Paris, France; PRES Sorbonne Paris Cité, Université Paris Descartes, Paris, France; Faculté des Sciences de la Santé de l'Université d'Abomey-Calavi, Centre d'étude et de recherche sur le paludisme associé à la grossesse et à l'enfance, Cotonou, Bénin.
Adrian J F
AJ
Luty
Institut de Recherche pour le Développement, UMR216 Mère et enfant face aux infections tropicales, Paris, France; PRES Sorbonne Paris Cité, Université Paris Descartes, Paris, France.
Philippe
P
Deloron
Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Science, University of Copenhagen, and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
Thor G
TG
Theander
ExpreS2ion Biotechnologies, SCION-DTU Science Park, Hørsholm, Denmark.
Charlotte
C
Dyring
Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Science, University of Copenhagen, and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
Ali
A
Salanti
D000818:Animals; D000917:Antibody Formation / Q000276:immunology*; D000953:Antigens, Protozoan / Q000276:immunology*; D003429:Cross Reactions / Q000276:immunology; D004331:Drosophila melanogaster / Q000378:metabolism; D005260:Female; D006801:Humans; D017780:Malaria Vaccines / Q000276:immunology*; D016778:Malaria, Falciparum / Q000276:immunology / Q000517:prevention & control*; D010920:Placenta / Q000276:immunology / Q000469:parasitology*; D010963:Plasmodium falciparum / Q000276:immunology; D011247:Pregnancy; D015202:Protein Engineering / Q000379:methods; D011994:Recombinant Proteins
D000953:Antigens, Protozoan; D017780:Malaria Vaccines; D011994:Recombinant Proteins; C512601:VAR2CSA protein, Plasmodium falciparum