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J Virol. 2017 Jan 3;91(2). pii: e01605-16. doi: 10.1128/JVI.01605-16. Print 2017 Jan 15.

Visualization of HIV T Cell Virological Synapses and Virus-Containing Compartments by Three-Dimensional Correlative Light and Electron Microscopy.

Author information

1
Division of Infectious Disease, Department of Medicine, Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA.
2
Simons Electron Microscopy Center, New York Structural Biology Center, New York, New York, USA.
3
Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, New York, USA.
4
Division of Infectious Disease, Department of Medicine, Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA ben.chen@mssm.edu.

Abstract

Virological synapses (VS) are adhesive structures that form between infected and uninfected cells to enhance the spread of HIV-1. During T cell VS formation, viral proteins are actively recruited to the site of cell-cell contact where the viral material is efficiently translocated to target cells into heterogeneous, protease-resistant, antibody-inaccessible compartments. Using correlative light and electron microscopy (CLEM), we define the membrane topography of the virus-containing compartments (VCC) where HIV is found following VS-mediated transfer. Focused ion beam scanning electron microscopy (FIB-SEM) and serial sectioning transmission electron microscopy (SS-TEM) were used to better resolve the fluorescent Gag-containing structures within the VCC. We found that small punctate fluorescent signals correlated with single viral particles in enclosed vesicular compartments or surface-localized virus particles and that large fluorescent signals correlated with membranous Gag-containing structures with unknown pathological function. CLEM imaging revealed distinct pools of newly deposited viral proteins within endocytic and nonendocytic compartments in VS target T cells.

IMPORTANCE:

This study directly correlates individual virus-associated objects observed in light microscopy with ultrastructural features seen by electron microscopy in the HIV-1 virological synapse. This approach elucidates which infection-associated ultrastructural features represent bona fide HIV protein complexes. We define the morphology of some HIV cell-to-cell transfer intermediates as true endocytic compartments and resolve unique synapse-associated viral structures created by transfer across virological synapses.

KEYWORDS:

Gag; HIV-1; T cells; correlative light and electron microscopy; endosome; focused ion beam electron microscopy; transmission electron microscopy; virological synapses; virus dissemination

PMID:
27847357
PMCID:
PMC5215336
DOI:
10.1128/JVI.01605-16
[Indexed for MEDLINE]
Free PMC Article

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