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Structure and Characterisation of a Key Epitope in the Conserved C-Terminal Domain of the Malaria Vaccine Candidate MSP2.
- Source :
-
Journal of molecular biology [J Mol Biol] 2017 Mar 24; Vol. 429 (6), pp. 836-846. Date of Electronic Publication: 2017 Feb 08. - Publication Year :
- 2017
-
Abstract
- Merozoite surface protein 2 (MSP2) is an intrinsically disordered antigen that is abundant on the surface of the malaria parasite Plasmodium falciparum. The two allelic families of MSP2, 3D7 and FC27, differ in their central variable regions, which are flanked by highly conserved C-terminal and N-terminal regions. In a vaccine trial, full-length 3D7 MSP2 induced a strain-specific protective immune response despite the detectable presence of conserved region antibodies. This work focuses on the conserved C-terminal region of MSP2, which includes the only disulphide bond in the protein and encompasses key epitopes recognised by the mouse monoclonal antibodies 4D11 and 9H4. Although the 4D11 and 9H4 epitopes are overlapping, immunofluorescence assays have shown that the mouse monoclonal antibody 4D11 binds to MSP2 on the merozoite surface with a much stronger signal than 9H4. Understanding the structural basis for this antigenic difference between these antibodies will help direct the design of a broad-spectrum and MSP2-based malaria vaccine. 4D11 and 9H4 were reengineered into antibody fragments [variable region fragment (Fv) and single-chain Fv (scFv)] and were validated as suitable models for their full-sized IgG counterparts by surface plasmon resonance and isothermal titration calorimetry. An alanine scan of the 13-residue epitope 3D7-MSP2 <subscript>207-222</subscript> identified the minimal binding epitope of 4D11 and the key residues involved in binding. A 2.2-Å crystal structure of 4D11 Fv bound to the eight-residue epitope NKENCGAA provided valuable insight into the possible conformation of the C-terminal region of MSP2 on the parasite. This work underpins continued efforts to optimise recombinant MSP2 constructs for evaluation as potential vaccine candidates.<br /> (Copyright © 2017 Elsevier Ltd. All rights reserved.)
- Subjects :
- Animals
Antibodies, Monoclonal chemistry
Antibodies, Monoclonal immunology
Antibodies, Protozoan chemistry
Antibodies, Protozoan immunology
Antigens, Protozoan chemistry
Calorimetry
Crystallography, X-Ray
Epitopes chemistry
Malaria Vaccines chemistry
Malaria Vaccines genetics
Malaria Vaccines immunology
Mice
Models, Molecular
Protein Binding
Protein Conformation
Protozoan Proteins chemistry
Surface Plasmon Resonance
Antigens, Protozoan genetics
Antigens, Protozoan immunology
Epitopes genetics
Epitopes immunology
Plasmodium falciparum genetics
Plasmodium falciparum immunology
Protozoan Proteins genetics
Protozoan Proteins immunology
Subjects
Details
- Language :
- English
- ISSN :
- 1089-8638
- Volume :
- 429
- Issue :
- 6
- Database :
- MEDLINE
- Journal :
- Journal of molecular biology
- Publication Type :
- Academic Journal
- Accession number :
- 28189425
- Full Text :
- https://doi.org/10.1016/j.jmb.2017.02.003