Utilizing nanobody technology to target non-immunodominant domains of VAR2CSA.
Placental malaria is a major health problem for both pregnant women and their fetuses in malaria endemic regions. It is triggered by the accumulation of Plasmodium falciparum-infected erythrocytes (IE) in the intervillous spaces of the placenta and is associated with foetal growth restriction and maternal anemia. IE accumulation is supported by the binding of the parasite-expressed protein VAR2CSA to placental chondroitin sulfate A (CSA). Defining specific CSA-binding epitopes of VAR2CSA, against which to target the immune response, is essential for the development of a vaccine aimed at blocking IE adhesion. However, the development of a VAR2CSA adhesion-blocking vaccine remains challenging due to (i) the large size of VAR2CSA and (ii) the extensive immune selection for polymorphisms and thereby non-neutralizing B-cell epitopes. Camelid heavy-chain-only antibodies (HcAbs) are known to target epitopes that are less immunogenic to classical IgG and, due to their small size and protruding antigen-binding loop, able to reach and recognize cryptic, conformational epitopes which are inaccessible to conventional antibodies. The variable heavy chain (VHH) domain is the antigen-binding site of camelid HcAbs, the so called Nanobody, which represents the smallest known (15 kDa) intact, native antigen-binding fragment. In this study, we have used the Nanobody technology, an approach new to malaria research, to generate small and functional antibody fragments recognizing unique epitopes broadly distributed on VAR2CSA.
Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
Sisse B
SB
Ditlev
Cellular and Molecular Immunology Research Unit, Vrije Universiteit Brussel, Brussels, Belgium ; Department of Structural Biology, VIB, Brussels, Belgium.
Raluca
R
Florea
Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
Morten A
MA
Nielsen
Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
Thor G
TG
Theander
Cellular and Molecular Immunology Research Unit, Vrije Universiteit Brussel, Brussels, Belgium ; Department of Structural Biology, VIB, Brussels, Belgium.
Stefan
S
Magez
The University of Melbourne, Department of Medicine, Parkville, Victoria, Australia ; Victorian Infectious Diseases Service, Royal Melbourne Hospital, Parkville, Victoria, Australia.
Philippe
P
Boeuf
Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
Ali
A
Salanti
D000595:Amino Acid Sequence; D000818:Animals; D000953:Antigens, Protozoan / Q000737:chemistry / Q000276:immunology*; D002161:Camelids, New World; D002809:Chondroitin Sulfates / Q000737:chemistry / Q000378:metabolism; D000939:Epitopes / Q000737:chemistry / Q000276:immunology; D004912:Erythrocytes / Q000469:parasitology; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000096:biosynthesis / Q000737:chemistry / Q000276:immunology*; D016778:Malaria, Falciparum / Q000276:immunology / Q000517:prevention & control; D008969:Molecular Sequence Data; D019151:Peptide Library; D010963:Plasmodium falciparum / Q000737:chemistry / Q000276:immunology*; D011485:Protein Binding; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000276:immunology; D016415:Sequence Alignment; D061905:Single-Domain Antibodies / Q000096:biosynthesis / Q000737:chemistry / Q000276:immunology*
D000953:Antigens, Protozoan; D000939:Epitopes; D007143:Immunoglobulin Heavy Chains; D019151:Peptide Library; D011994:Recombinant Proteins; D061905:Single-Domain Antibodies; C512601:VAR2CSA protein, Plasmodium falciparum; D002809:Chondroitin Sulfates