title: Characterization of a novel inhibitory human monoclonal antibody directed against Plasmodium falciparum Apical Membrane Antigen 1.
abstract: Malaria remains a major challenge to global health causing extensive morbidity and mortality. Yet, there is no efficient vaccine and the immune response remains incompletely understood. Apical Membrane Antigen 1 (AMA1), a leading vaccine candidate, plays a key role during merozoite invasion into erythrocytes by interacting with Rhoptry Neck Protein 2 (RON2). We generated a human anti-AMA1-antibody (humAbAMA1) by EBV-transformation of sorted B-lymphocytes from a Ghanaian donor and subsequent rescue of antibody variable regions. The antibody was expressed in Nicotiana benthamiana and in HEK239-6E, characterized for binding specificity and epitope, and analyzed for its inhibitory effect on Plasmodium falciparum. The generated humAbAMA1 shows an affinity of 106-135 pM. It inhibits the parasite strain 3D7A growth in vitro with an expression system-independent IC50-value of 35 μg/ml (95% confidence interval: 33 μg/ml-37 μg/ml), which is three to eight times lower than the IC50-values of inhibitory antibodies 4G2 and 1F9. The epitope was mapped to the close proximity of the RON2-peptide binding groove. Competition for binding between the RON2-peptide and humAbAMA1 was confirmed by surface plasmon resonance spectroscopy measurements. The particularly advantageous inhibitory activity of this fully human antibody might provide a basis for future therapeutic applications.
authors.affiliation: Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.|Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany.
authors.forename: Dominika J
authors.initials: DJ
authors.lastname: Maskus
authors.affiliation: Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany.
authors.forename: Michał
authors.initials: M
authors.lastname: Królik
authors.affiliation: Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Bethke
authors.affiliation: Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Spiegel
authors.affiliation: Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Kapelski
authors.affiliation: Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
authors.forename: Melanie
authors.initials: M
authors.lastname: Seidel
authors.affiliation: Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.|Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany.|Faculty of Allied Health Sciences, Kwame Nkrumah University of Science and Technology, KNUST, Kumasi, Ghana.
authors.forename: Otchere
authors.initials: O
authors.lastname: Addai-Mensah
authors.affiliation: Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Reimann
authors.affiliation: Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
authors.forename: Torsten
authors.initials: T
authors.lastname: Klockenbring
authors.affiliation: Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.|Institute for Applied Medical Engineering at RWTH Aachen University and Hospital, Department of Experimental Medicine and Immunotherapy, Aachen, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Barth
authors.affiliation: Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.|Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Fischer
authors.affiliation: Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.|Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany.|Institute for Applied Medical Engineering at RWTH Aachen University and Hospital, Department of Experimental Medicine and Immunotherapy, Aachen, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Fendel
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology*; D000953:Antigens, Protozoan / Q000276:immunology*; D001402:B-Lymphocytes / Q000469:parasitology; D001667:Binding, Competitive; D002460:Cell Line; D000939:Epitopes / Q000276:immunology; D004912:Erythrocytes / Q000276:immunology / Q000469:parasitology*; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D020128:Inhibitory Concentration 50; D007963:Leukocytes, Mononuclear / Q000469:parasitology; D008565:Membrane Proteins / Q000276:immunology*; D008968:Molecular Conformation; D010963:Plasmodium falciparum / Q000276:immunology*; D011485:Protein Binding; D015800:Protozoan Proteins / Q000276:immunology*; D020349:Surface Plasmon Resonance; D014026:Nicotiana
chemical_list: D000911:Antibodies, Monoclonal; D000953:Antigens, Protozoan; D000939:Epitopes; D007074:Immunoglobulin G; D008565:Membrane Proteins; D015800:Protozoan Proteins; C090077:apical membrane antigen I, Plasmodium