Interrogating a new HIV-1 vaccine target in the gp41 C-heptad repeat
Abstract/Contents
- Abstract
- HIV-1 infection requires viral and cell membrane fusion, a process which relies on the gp41 N-heptad repeat (NHR) and C-heptad repeat (CHR) of the viral glycoprotein Env. When the CHR adopts an α‑helical conformation, one face is composed of highly conserved residues and is a validated target for HIV-1 inhibition, suggesting that this conserved α-helical face might be an effective vaccine target. No neutralizing antibodies targeting the highly conserved α-helical face of the CHR have been described, although an engineered protein targeting this epitope, 5-Helix, shows potent neutralizing activity against multiple viral strains. We have identified the first such examples of neutralizing antibodies against this epitope through parallel antibody selections, an important proof-of-principle for CHR-targeting vaccine efforts. First, we use mutagenesis and selection of a yeast surface-display library to isolate two novel antibodies that target this epitope, A24.3 and A25.2. Surprisingly, the X-ray crystal structure of the A24.3 antigen-binding fragment (Fab) indicates that CHR binding is concomitant with displacement of the variable light domain and is mediated by germline-conserved framework residues on the variable heavy (VH) domain. We next designed a stapled CHR peptide to identify novel antibodies targeting this highly conserved epitope from a ~7.6 x 10^10-member single-chain variable fragment (scFv) library designed by Distributed Bio: the SuperHuman Library 2.0. We identified 52 novel anti-CHR scFv clones, many of which bind multiple CHR peptides representing the consensus sequences of distinct clades of HIV-1. In order to functionally evaluate these novel antibodies, we assessed their viral neutralization activity using Env-pseudotyped lentivirus. We first assessed the efficacy of 5-Helix against a panel of HIV-1 strains representing circulating strains worldwide and found 5-Helix shows broad neutralization activity across viral clades and neutralization tiers. We next found both A2 antibodies and Distributed Bio scFvs neutralize the tier-1 HXB2 strain, the first examples of neutralizing antibodies targeting this conserved epitope in the CHR. Additionally, A25.2 VH antibody shows cross-clade neutralization, inhibiting HIV-1 strains representing diverse CHR sequences. Taken together, these neutralization studies combined with our biochemical and structural characterization provide proof-of-concept that the conserved α-helical face of the CHR could be effectively targeted by antibodies, potentially opening new avenues in vaccine development for HIV-1 and viruses with closely related class-I fusion mechanisms.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2021; ©2021 |
| Publication date | 2021; 2021 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Bell, Benjamin Nikola |
|---|---|
| Degree supervisor | Kim, Peter, 1958- |
| Thesis advisor | Kim, Peter, 1958- |
| Thesis advisor | Brünger, Axel T |
| Thesis advisor | Jardetzky, Theodore |
| Thesis advisor | Yeh, Ellen |
| Degree committee member | Brünger, Axel T |
| Degree committee member | Jardetzky, Theodore |
| Degree committee member | Yeh, Ellen |
| Associated with | Stanford University, Department of Molecular and Cellular Physiology |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Benjamin N. Bell. |
|---|---|
| Note | Submitted to the Department of Molecular and Cellular Physiology. |
| Thesis | Thesis Ph.D. Stanford University 2021. |
| Location | https://purl.stanford.edu/ds113mn3878 |
Access conditions
- Copyright
- © 2021 by Benjamin Nikola Bell
- License
- This work is licensed under a Creative Commons Attribution Non Commercial Share Alike 3.0 Unported license (CC BY-NC-SA).
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