Characterization of Inhibitors and Monoclonal Antibodies That Modulate the Interaction between Plasmodium falciparum Adhesin PfRh4 with Its Erythrocyte Receptor Complement Receptor 1.
Plasmodium falciparum parasites must invade red blood cells to survive within humans. Entry into red blood cells is governed by interactions between parasite adhesins and red blood cell receptors. Previously we identified that P. falciparum reticulocyte binding protein-like homologue 4 (PfRh4) binds to complement receptor 1 (CR1) to mediate entry of malaria parasites into human red blood cells. In this report we characterize a collection of anti-PfRh4 monoclonal antibodies and CR1 protein fragments that modulate the interaction between PfRh4 and CR1. We identify an anti-PfRh4 monoclonal that blocks PfRh4-CR1 interaction in vitro, inhibits PfRh4 binding to red blood cells, and as a result abolishes the PfRh4-CR1 invasion pathway in P. falciparum. Epitope mapping of anti-PfRh4 monoclonal antibodies identified distinct functional regions within PfRh4 involved in modulating its interaction with CR1. Furthermore, we designed a set of protein fragments based on extensive mutagenesis analyses of the PfRh4 binding site on CR1 and determined their interaction affinities using surface plasmon resonance. These CR1 protein fragments bind tightly to PfRh4 and also function as soluble inhibitors to block PfRh4 binding to red blood cells and to inhibit the PfRh4-CR1 invasion pathway. Our findings can aid future efforts in designing specific single epitope antibodies to block P. falciparum invasion via complement receptor 1.
From the Walter and Eliza Hall Institute, Parkville, Victoria 3052, Australia.
Nicholas T Y
NT
Lim
the Institute of Pharmacology of Natural Products and Clinical Pharmacology, Ulm University, Helmholtzstrasse 20, D-89081 Ulm, Germany.
Markus J
MJ
Harder
From the Walter and Eliza Hall Institute, Parkville, Victoria 3052, Australia, the Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia, and.
Alexander T
AT
Kennedy
From the Walter and Eliza Hall Institute, Parkville, Victoria 3052, Australia, the Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia, and.
Clara S
CS
Lin
From the Walter and Eliza Hall Institute, Parkville, Victoria 3052, Australia, the Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia, and the School of Chemistry, University of Edinburgh, Edinburgh EH93JJ, Scotland, United Kingdom.
Christopher
C
Weir
From the Walter and Eliza Hall Institute, Parkville, Victoria 3052, Australia, the Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia, and.
Alan F
AF
Cowman
From the Walter and Eliza Hall Institute, Parkville, Victoria 3052, Australia, the Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia, and.
Melissa J
MJ
Call
the Institute of Pharmacology of Natural Products and Clinical Pharmacology, Ulm University, Helmholtzstrasse 20, D-89081 Ulm, Germany.
Christoph Q
CQ
Schmidt
From the Walter and Eliza Hall Institute, Parkville, Victoria 3052, Australia, the Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia, and tham@wehi.edu.au.
Wai-Hong
http://orcid.org/0000-0001-7950-8699
WH
Tham
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D004912:Erythrocytes / Q000378:metabolism*; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism*; D011951:Receptors, Complement / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D008565:Membrane Proteins; D015800:Protozoan Proteins; C464927:RH4 protein, Plasmodium falciparum; D011951:Receptors, Complement
PfRh4; complement; complement receptor 1; host-pathogen interaction; invasion; malaria; monoclonal antibody; plasmodium