Identification and characterization of neutralizing HIV antibodies targeting the gp41 trimer-of-hairpins structure
Abstract/Contents
- Abstract
- Despite the extensive amount of time and resources that have been put into HIV research over the past 40 years, the production of an effective preventative vaccine has remained elusive. More recently, vaccine efforts have been reinvigorated with the identification of more broadly neutralizing antibodies (bNAbs) that give hope to the success of B cell focused vaccine approaches. Neutralizing antibodies target the envelope protein (env), which is the only protein expressed on the outside of the HIV membrane. Env is composed of two subunits: gp120, which is responsible for binding to cellular receptors, and gp41, which contains the membrane fusion machinery. Although several broadly neutralizing epitopes have been identified, attempts to generate bNAbs in a vaccine setting have been underwhelming. We therefore set out to characterize new bNAbs against highly conserved regions of the gp41 subunit that are exposed in the pre-hairpin intermediate structure during viral fusion. Since few neutralizing epitopes have previously been characterized for gp41, we first explored HIV patient antibody responses to the N-heptad repeat (NHR) and C-heptad repeat (CHR) regions of gp41. After identifying individuals that produced antibodies against these structures, we single cell sorted their B cells and sequenced the heavy and light chains of their antibody genes, leading to the discovery of three novel anti-CHR neutralizing antibodies. A 3.5 Å crystal structure of the most potent neutralizing antibody, 1CB6, determined that these antibodies targeted the immunodominant cluster II epitope, previously regarded as a non-neutralizing epitope. Similarly to other cluster II antibodies, we observed that the three neutralizing antibodies targeted the CHR as exposed in the gp41 trimer-of-hairpins structure, which is thought to form at the fusion of viral and host membranes. Finally, by utilizing FcγRI on TZM-bl cells and the fusion inhibitor sensitive L565Q env mutation, we demonstrate that cluster II antibodies neutralize during the fusion pathway. These experiments definitively demonstrate that neutralizing antibodies target the cluster II epitope. Additionally, these experiments influence our understanding of gp41 collapse and the fusion process. Exposure of the cluster II epitope on the gp41 trimer-of-hairpins and the high affinity of these antibodies for this structure suggest the formation of a late stage fusion intermediate that can be targeted for the neutralization of HIV.
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 | Lyons, Michael Morris |
|---|---|
| Degree supervisor | Kim, Peter, 1958- |
| Thesis advisor | Kim, Peter, 1958- |
| Thesis advisor | Boothroyd, John C |
| Thesis advisor | Idoyaga, Juliana |
| Thesis advisor | Relman, David A |
| Degree committee member | Boothroyd, John C |
| Degree committee member | Idoyaga, Juliana |
| Degree committee member | Relman, David A |
| Associated with | Stanford University, Department of Microbiology and Immunology |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Michael M. Lyons. |
|---|---|
| Note | Submitted to the Department of Microbiology and Immunology. |
| Thesis | Thesis Ph.D. Stanford University 2021. |
| Location | https://purl.stanford.edu/jq709wf2182 |
Access conditions
- Copyright
- © 2021 by Michael Morris Lyons
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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