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

ELife
M. S. LadinskyPamela J Bjorkman

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.

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Citations

Apr 20, 2021·ELife·Christophe CaillatWinfried Weissenhorn
May 1, 2021·Viruses·Tianshu XiaoBing Chen
Jun 3, 2021·Viruses·Ashley Lauren Bennett, Rory Henderson

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Methods Mentioned

BETA
X-ray
electron tomography
electron microscopy
transfection
size exclusion chromatography

Software Mentioned

SerialEM
IMOD

Related Concepts