Biology subjects

Shaffer, K.

Publications and source records attributed to Shaffer, K..

3 recordsLinked to original sources

bioRxiv2024

A broadly-neutralizing antibody against Ebolavirus glycoprotein that potentiates the breadth and neutralization potency of other antibodies

Ebolavirus disease (EVD) is caused by multiple species of Ebolavirus. Monoclonal antibodies (mAbs) against the virus glycoprotein (GP) are the only class of therapeutic approved for treatment of EVD caused by Zaire ebolavirus (EBOV). Therefore, mAbs targeting multiple Ebolavirus species may represent the next generation of EVD therapeutics. Broadly reactive anti-GP mAbs were produced; among these, mAbs 11886 and 11883 were broadly neutralizing in vitro. A 3.0 [A] cryo-electron microscopy structure of EBOV GP bound to both mAbs shows that 11886 binds a novel epitope bridging the glycan cap (GC), 310 pocket and GP2 N-terminus, whereas 11883 binds the receptor binding region (RBR) and GC. In vitro, 11886 synergized with a range of mAbs with epitope specificities spanning the RBR/GC, including 11883. Notably, 11886 increased the breadth of neutralization by partner mAbs against different Ebolavirus species. These data provide a strategic route to design improved mAb-based next-generation EVD therapeutics.

immunology↗

bioRxiv2022

Structure of the Inmazeb cocktail and resistance to escape against Ebola virus

Monoclonal antibodies can provide important pre- or post-exposure protection against disease for those not yet vaccinated or in individuals that fail to mount a protective immune response after vaccination. A key concern in use of monotherapy monoclonal antibody products lies in the high risk of mutagenic escape. Inmazeb (REGN-EB3), a three-antibody cocktail against Ebola virus, demonstrated efficacy in lessening disease course and improving survival in a randomized, controlled trial. Here we present the cryoEM structure at 3.1 [A] of the Ebola virus glycoprotein, determined without symmetry averaging, in a simultaneous complex with eight Fab fragments of antibodies in the Inmazeb cocktail. This structure allows modeling of previously disordered portions of the glycan cap, maps the non-overlapping epitopes of Inmazeb, and illuminates the basis for complementary activities, as well as residues that are critical for resistance to escape by each component of this cocktail and other clinically relevant antibodies. We also provide direct evidence that, unlike monotherapy treatments, including those targeting conserved epitopes, the Inmazeb protects against the rapid emergence of EBOV escape mutants and supports the benefit of the combination approach.

biophysics↗

bioRxiv2022

Glycan shield of the ebolavirus envelope glycoprotein GP

The envelope glycoprotein GP of the ebolaviruses is essential for host cell attachment and entry. It is also the primary target of the protective and neutralizing antibody response in both natural infection and vaccination. GP is heavily glycosylated with up to 17 predicted N-linked sites, numerous O-linked glycans in its disordered mucin-like domain (MLD), and three predicted C-linked mannosylation sites. Glycosylation of GP is important for host cell attachment to cell-surface lectins, as well as GP stability and fusion activity. Moreover, it has been shown to shield GP from neutralizing activity of serum antibodies. Here, we use mass spectrometry-based glycoproteomics to profile the site-specific glycosylation patterns of ebolavirus GP. We detect up to 16 unique O-linked glycosylation sites in the mucin-like domain, as well as two O-linked sites in the head and glycan cap domains of the receptor-binding GP1 subunit. Multiple O-linked glycans are observed at the S/T residues of N-linked glycosylation sequons, suggesting possible crosstalk between the two types of modifications. We also confirmed the presence of C-mannosylation at W288 in the context of trimeric GP. We find heterogenous, complex N-linked glycosylation at the majority of predicted sites as expected. By contrast, the two conserved sites N257 and N563 are enriched in unprocessed high-mannose and hybrid glycans, suggesting a role in host-cell attachment via DC-SIGN/L-SIGN. We discuss our findings in the context of antibody recognition to show how glycans contribute to and restrict neutralization epitopes. This information on how N-, O-, and C-linked glycans together build the heterogeneous glycan shield of GP can guide future immunological studies and functional interpretation of ebolavirus GP-antibody interactions.

biochemistry↗