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Electron tomography visualization of HIV-1 fusion with target cells using inhibitors to trap the prehairpin intermediate

  1. Mark S Ladinsky
  2. Priyanthi N P Gnanapragasam
  3. Zhi Yang
  4. Anthony P West
  5. Michael S Kay
  6. Pamela J Bjorkman  Is a corresponding author
  1. California Institute of Technology, United States
  2. University of Utah School of Medicine, United States
Research Article
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Cite this article as: eLife 2020;9:e58411 doi: 10.7554/eLife.58411

Abstract

Fusion of HIV-1 with the membrane of its target cell, an obligate first step in virus infectivity, is mediated by binding of the viral envelope (Env) spike protein to its receptors, CD4 and CCR5/CXCR4, on the cell surface. The process of viral fusion appears to be fast compared with viral egress and has not been visualized by EM. To capture fusion events, the process must be curtailed by trapping Env-receptor binding at an intermediate stage. We have used fusion inhibitors to trap HIV-1 virions attached to target cells by Envs in an extended pre-hairpin intermediate state. Electron tomography revealed HIV-1 virions bound to TZM-bl cells by 2-4 narrow spokes, with slightly more spokes present when evaluated with mutant virions that lacked the Env cytoplasmic tail. These results represent the first direct visualization of the hypothesized pre-hairpin intermediate of HIV-1 Env and improve our understanding of Env-mediated HIV-1 fusion and infection of host cells.

Data availability

Raw datasets are freely available upon request. Interested parties should contact ladinsky@caltech.edu, and we will place requested datasets onto an externally accessible Caltech Box Server. Requestors will then be provided with a direct URL link from which they can download the files at their convenience.

Article and author information

Author details

  1. Mark S Ladinsky

    Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
    Competing interests
    No competing interests declared.

  2. Priyanthi N P Gnanapragasam

    Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
    Competing interests
    No competing interests declared.

  3. Zhi Yang

    Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
    Competing interests
    No competing interests declared.

  4. Anthony P West

    Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
    Competing interests
    No competing interests declared.

  5. Michael S Kay

    Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-3186-9684

  6. Pamela J Bjorkman

    Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
    For correspondence
    bjorkman@caltech.edu
    Competing interests
    Pamela J Bjorkman, Reviewing editor, eLife.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-2277-3990

Funding

National Institute of General Medical Sciences (2 P50 AI150464)

  • Michael S Kay
  • Pamela J Bjorkman

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Axel T Brunger, Stanford University, United States

Publication history

  1. Received: April 29, 2020
  2. Accepted: July 21, 2020
  3. Accepted Manuscript published: July 22, 2020 (version 1)
  4. Version of Record published: July 31, 2020 (version 2)

Copyright

© 2020, Ladinsky et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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