Mapping the Binding Site of a Cross-Reactive Plasmodium falciparum PfEMP1 Monoclonal Antibody Inhibitory of ICAM-1 Binding

0455396 - MBÚ 2016 RIV US eng J - Journal Article
Lennartz, F. - Bengtsson, A. - Olsen, R. W. - Joergensen, L. - Brown, A. - Remy, L. - Man, Petr - Forest, E. - Barfod, L. K. - Adams, Y. - Higgins, M. K. - Jensen, A. T. R.
Mapping the Binding Site of a Cross-Reactive Plasmodium falciparum PfEMP1 Monoclonal Antibody Inhibitory of ICAM-1 Binding.
Journal of Immunology. Roč. 195, č. 7 (2015), s. 3273-3283. ISSN 0022-1767. E-ISSN 1550-6606
R&D Projects: GA MŠMT(CZ) ED1.1.00/02.0109
Grant - others:OPPC(XE) CZ.2.16/3.1.00/24023
Institutional support: RVO:61388971
Keywords : INTERCELLULAR-ADHESION MOLECULE-1 * SMALL-ANGLE SCATTERING * ERYTHROCYTE-MEMBRANE PROTEIN-1
Subject RIV: CE - Biochemistry
Impact factor: 4.985, year: 2015

The virulence of Plasmodium falciparum is linked to the ability of infected erythrocytes (IE) to adhere to the vascular endothelium, mediated by P. falciparum erythrocyte membrane protein 1 (PfEMP1). In this article, we report the functional characterization of an mAb that recognizes a panel of PfEMP1s and inhibits ICAM-1 binding. The 24E9 mouse mAb was raised against PFD1235w DBL beta 3_D4, a domain from the group A PfEMP1s associated with severe malaria. 24E9 recognizes native PfEMP1 expressed on the IE surface and shows cross-reactivity with and cross-inhibition of the ICAM-1 binding capacity of domain cassette 4 PfEMP1s. 24E9 Fab fragments bind DBL beta 3_D4 with nanomolar affinity and inhibit ICAM-1 binding of domain cassette 4-expressing IE. The antigenic regions targeted by 24E9 Fab were identified by hydrogen/deuterium exchange mass spectrometry and revealed three discrete peptides that are solvent protected in the complex. When mapped onto a homology model of DBL beta 3_D4, these cluster to a defined, surface-exposed region on the convex surface of DBL beta 3_D4. Mutagenesis confirmed that the site most strongly protected is necessary for 24E9 binding, which is consistent with a low-resolution structure of the DBL beta 3_D4::24E9 Fab complex derived from small-angle x-ray scattering. The convex surface of DBL beta 3_D4 has previously been shown to contain the ICAM-1 binding site of DBL beta domains, suggesting that the mAb acts by occluding the ICAM-1 binding surface. Conserved epitopes, such as those targeted by 24E9, are promising candidates for the inclusion in a vaccine interfering with ICAM-1-specific adhesion of group A PfEMP1 expressed by P. falciparum IE during severe malaria
Permanent Link: http://hdl.handle.net/11104/0256013