The binding of a monoclonal antibody to the apical region of SCARB2 blocks EV71 infection

Abstract

Entero virus 71 (EV71) causes hand, foot, and mouth disease (HFMD) and occasionally leads to severe neurological complications and even death. Scavenger receptor class B member 2 (SCARB2) is a functional receptor for EV71, that mediates viral attachment, internalization, and uncoating. However, the exact binding site of EV71 on SCARB2 is unknown. In this study, we generated a monoclonal antibody (mAb) that binds to human but not mouse SCARB2. It is named JL2, and it can effectively inhibit EV71 infection of target cells. Using a set of chimeras of human and mouse SCARB2, we identified that the region containing residues 77–113 of human SCARB2 contributes significantly to JL2 binding. The structure of the SCARB2-JL2 complex revealed that JL2 binds to the apical region of SCARB2 involving α-helices 2, 5, and 14. Our results provide new insights into the potential binding sites for EV71 on SCARB2 and the molecular mechanism of EV71 entry.Electronic supplementary materialThe online version of this article (doi:10.1007/s13238-017-0405-7) contains supplementary material, which is available to authorized users.

Unexpected mode of engagement between enterovirus 71 and its receptor SCARB2

“…2a) 6 . This is consistent with previous observations that the C-terminal end of 4 is directly involved in attachment and the observation that 5 forms part of the epitope of an Fab which binds SCARB2 to prevent virus attachment 19 . It has been noted that this helical bundle undergoes pH dependent conformational changes, and it has been proposed that these changes are involved in a pH dependent triggering of viral uncoating 3,6 .…”

Novel Naturally Occurring Mutations of Enterovirus 71 Associated With Disease Severity

“…Recently, the initial attachment complex between EV-A71 and SCARB2 at low pH was visualized by cryoEM ( Zhou et al, 2019 ). It reveals that SCARB2 binds EV-A71 on the southern rim of the canyon, rather than across the canyon as predicted previously ( Chen et al, 2012 ; Dang et al, 2014 ; Zhang et al, 2017 ). This new structure suggests an allosteric mechanism for receptor binding, and the subsequent uncoating of EV-A71 in the low-pH lumen of endosome or lysosome.…”

CD36 family members are TCR-independent ligands for CD1 antigen-presenting molecules

“…DNA constructs encoding anti-SCARB2 antibody heavy and light chain variable domains (clone JL2 78 ) were synthesized (ThermoFisher) and cloned into mammalian expression vectors containing a mouse IGHV signal peptide and IgG1 constant regions. Antibodies were expressed by transient transfection of mammalian Expi293F cells and purified using Protein G column chromatography (GE), followed by buffer-exchange into PBS ( Fig.…”