scholarly journals A Replication-Competent HIV Clone Carrying GFP-Env Reveals Rapid Env Recycling at the HIV-1 T Cell Virological Synapse

Viruses ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 38
Author(s):  
Lili Wang ◽  
Alice Sandmeyer ◽  
Wolfgang Hübner ◽  
Hongru Li ◽  
Thomas Huser ◽  
...  
Keyword(s):  
Virological Synapse ◽  
Target Cells ◽  
Structural Protein ◽  
Combined Use ◽  
Infected Cells ◽  
Virological Synapses ◽  
Dynamic Exchange ◽  
Endocytic Compartments ◽  
Viral Transfer ◽  
Hiv 1

HIV-1 infection is enhanced by cell–cell adhesions between infected and uninfected T cells called virological synapses (VS). VS are initiated by the interactions of cell-surface HIV-1 envelope glycoprotein (Env) and CD4 on target cells and act as sites of viral assembly and viral transfer between cells. To study the process that recruits and retains HIV-1 Env at the VS, a replication-competent HIV-1 clone carrying an Env-sfGFP fusion protein was designed to enable live tracking of Env within infected cells. Combined use of surface pulse-labeling of Env and fluorescence recovery after photobleaching (FRAP) studies, enabled the visualization of the targeted accumulation and sustained recycling of Env between endocytic compartments (EC) and the VS. We observed dynamic exchange of Env at the VS, while the viral structural protein, Gag, was largely immobile at the VS. The disparate exchange rates of Gag and Env at the synapse support that the trafficking and/or retention of a majority of Env towards the VS is not maintained by entrapment by a Gag lattice or immobilization by binding to CD4 on the target cell. A FRAP study of an Env endocytosis mutant showed that recycling is not required for accumulation at the VS, but is required for the rapid exchange of Env at the VS. We conclude that the mechanism of Env accumulation at the VS and incorporation into nascent particles involves continuous internalization and targeted secretion rather than irreversible interactions with the budding virus, but that this recycling is largely dispensable for VS formation and viral transfer across the VS.

scholarly journals Recruitment of Env to the HIV-1 T cell virological synapse by targeted and sustained Env recycling

2020 ◽  
Author(s):  
Lili Wang ◽  
Alice Sandmeyer ◽  
Wolfgang Hübner ◽  
Hongru Li ◽  
Thomas Huser ◽  
...  
Keyword(s):  
Fluorescence Recovery After Photobleaching ◽  
Virological Synapse ◽  
Target Cells ◽  
Structural Protein ◽  
Rapid Exchange ◽  
Infected Cells ◽  
Virological Synapses ◽  
Dynamic Exchange ◽  
Viral Transfer ◽  
Hiv 1

ABSTRACTHIV-1 infection is enhanced by cell-cell adhesions between infected and uninfected T cells called virological synapses (VS). VS are initiated by the interactions of cell-surface HIV-1 envelope glycoprotein (Env) and CD4 on target cells and act as sites of viral assembly and viral transfer between cells. To study the process that recruits and retains HIV-1 Env at the VS, a replication-competent HIV-1 clone carrying an Env-sfGFP fusion protein was designed to enable live tracking of Env within infected cells. Using surface pulse-labeling of Env and fluorescence recovery after photobleaching (FRAP) studies, we observed targeted accumulation and sustained recycling of Env between the endocytic recycling compartment (ERC) and the VS. We observed dynamic exchange of Env at the VS while the viral structural protein, Gag, was largely immobile at the VS. The disparate exchange rates of Gag and Env at the synapse indicate that retention of Env is not likely to be maintained by entrapment into an immobile Gag lattice or through immobilizing interactions with CD4 on the target cell. A FRAP study of an Env endocytosis mutant showed that recycling is required for the rapid exchange of Env at the VS. We conclude that the mechanism of Env accumulation at the VS and incorporation into nascent particles involves continuous internalization and targeted secretion rather than irreversible interactions with the budding virus.

scholarly journals Predominant Mode of Human Immunodeficiency Virus Transfer between T Cells Is Mediated by Sustained Env-Dependent Neutralization-Resistant Virological Synapses

2007 ◽  
Vol 81 (22) ◽  
pp. 12582-12595 ◽  
Author(s):  
Ping Chen ◽  
Wolfgang Hübner ◽  
Matthew A. Spinelli ◽  
Benjamin K. Chen
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
Productive Infection ◽  
Target Cells ◽  
Free Virus ◽  
Virus Transfer ◽  
Immunodeficiency Virus ◽  
Virological Synapses ◽  
Viral Transfer ◽  
Hiv 1

ABSTRACT Cell-free human immunodeficiency virus type 1 (HIV-1) can initiate infections, but contact between infected and uninfected T cells can enhance viral spread through intercellular structures called virological synapses (VS). The relative contribution of VS to cell-free viral transfer has not been carefully measured. Using an ultrasensitive, fluorescent virus transfer assay, we estimate that when VS between HIV-expressing Jurkat T cells and primary CD4+ T cells are formed, cell-associated transfer of virus is 18,000-fold more efficient than uptake of cell-free virus. Furthermore, in contrast to cell-free virus uptake, the VS deposits virus rapidly into focal, trypsin-resistant compartments in target T cells. This massive virus internalization requires Env-CD4 receptor interactions but is resistant to inhibition by patient-derived neutralizing antisera that inhibit homologous cell-free virus. Deleting the Env cytoplasmic tail does not abrogate VS-mediated transfer, but it renders the VS sensitive to neutralizing antibodies, suggesting that the tail limits exposure of VS-neutralizing epitopes on the surface of infected cells. Dynamic live imaging of the VS reveals that HIV-expressing cells are polarized and make sustained, Env-dependent contacts with target cells through uropod-like structures. The polarized T-cell morphology, Env-CD4 coordinated adhesion, and viral transfer from HIV-infected to uninfected cells suggest that VS allows HIV-1 to evade antibody neutralization and to disseminate efficiently. Future studies will discern to what extent this massive viral transfer contributes to productive infection or viral dissemination through the migration of virus-carrying T cells.

scholarly journals Endocytic Motif on a Biotin-Tagged HIV-1 Env Modulates the Co-Transfer of Env and Gag during Cell-to-Cell Transmission

Viruses ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1729
Author(s):  
María Inés Barría ◽  
Raymond A. Alvarez ◽  
Kenneth Law ◽  
Deanna L. Wolfson ◽  
Thomas Huser ◽  
...  
Keyword(s):  
Fluorescent Imaging ◽  
Productive Infection ◽  
Live Cells ◽  
Cell Contact ◽  
Target Cells ◽  
Structural Protein ◽  
Cell Infection ◽  
Virological Synapses ◽  
Hiv 1 ◽  
Cell Cell

During HIV-1 transmission through T cell virological synapses, the recruitment of the envelope (Env) glycoprotein to the site of cell–cell contact is important for adhesion and for packaging onto nascent virus particles which assemble at the site. Live imaging studies in CD4 T cells have captured the rapid recruitment of the viral structural protein Gag to VSs. We explored the role of endocytic trafficking of Env initiated by a membrane proximal tyrosine motif during HIV transfer into target cells and examined the factors that allow Gag and Env to be transferred together across the synapse. To facilitate tracking of Env in live cells, we adapted an Env tagging method and introduced a biotin acceptor peptide (BAP) into the V4 loop of Env gp120, enabling sensitive fluorescent tracking of V4-biotinylated Env. The BAP-tagged and biotinylated HIVs were replication-competent in cell-free and cell-to-cell infection assays. Live cell fluorescent imaging experiments showed rapid internalized cell surface Env on infected cells. Cell–cell transfer experiments conducted with the Env endocytosis mutant (Y712A) showed increased transfer of Env. Paradoxically, this increase in Env transfer was associated with significantly reduced Gag transfer into target cells, when compared to viral transfer associated with WT Env. This Y712A Env mutant also exhibited an altered Gag/biotin Env fluorescence ratio during transfer that correlated with decreased productive cell-to-cell infection. These results may suggest that the internalization of Env into recycling pools plays an important role in the coordinated transfer of Gag and Env across the VS, which optimizes productive infection in target cells.

HIV-1 at the immunological and T-lymphocytic virological synapse

2008 ◽  
Vol 389 (10) ◽  
Author(s):  
Claudia Haller ◽  
Oliver T. Fackler
Keyword(s):  
T Lymphocyte ◽  
Immunological Synapse ◽  
Virological Synapse ◽  
Viral Spread ◽  
Immunodeficiency Virus ◽  
Cellular Signal ◽  
Virological Synapses ◽  
Opposing Effects ◽  
Viral Transfer ◽  
Hiv 1

AbstractCell-cell transmission of human immunodeficiency virus type 1 (HIV-1) is considered the most effective mode of viral spread in T-lymphocyte cultures. Evidence has accumulated that HIV-1 assembles polarized synaptic-like structures, referred to as virological synapses, as specialized sites of viral transfer. Interestingly, it was recently also discovered that HIV-1 impairs the formation of the structurally similar immunological synapse, thereby modulating exogenous T-lymphocyte stimulation to yield an optimal activation state for productive HIV-1 infection. The careful dissection of these opposing effects will contribute to our understanding of retroviral spread and cellular signal transduction machineries.

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

2016 ◽  
Vol 91 (2) ◽  
Author(s):  
Lili Wang ◽  
Edward T. Eng ◽  
Kenneth Law ◽  
Ronald E. Gordon ◽  
William J. Rice ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
T Cell ◽  
Ion Beam ◽  
Light And Electron Microscopy ◽  
Viral Proteins ◽  
Virological Synapse ◽  
Cell Contact ◽  
Target Cells ◽  
Virological Synapses ◽  
Hiv 1

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.

scholarly journals The versatile role of exosomes in human retroviral infections: from immunopathogenesis to clinical application

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jafar Rezaie ◽  
Cynthia Aslan ◽  
Mahdi Ahmadi ◽  
Naime Majidi Zolbanin ◽  
Fatah Kashanchi ◽  
...  
Keyword(s):  
Current Knowledge ◽  
Biological Fluids ◽  
Recipient Cell ◽  
Leukemia Virus ◽  
Target Cells ◽  
Modern Approach ◽  
Human T Cell ◽  
T Cell Leukemia Virus ◽  
Infected Cells ◽  
Hiv 1

AbstractEukaryotic cells produce extracellular vesicles (EVs) mediating intercellular communication. These vesicles encompass many bio-molecules such as proteins, nucleic acids, and lipids that are transported between cells and regulate pathophysiological actions in the recipient cell. Exosomes originate from multivesicular bodies inside cells and microvesicles shed from the plasma membrane and participate in various pathological conditions. Retroviruses such as Human Immunodeficiency Virus -type 1 (HIV-1) and Human T-cell leukemia virus (HTLV)-1 engage exosomes for spreading and infection. Exosomes from virus-infected cells transfer viral components such as miRNAs and proteins that promote infection and inflammation. Additionally, these exosomes deliver virus receptors to target cells that make them susceptible to virus entry. HIV-1 infected cells release exosomes that contribute to the pathogenesis including neurological disorders and malignancy. Exosomes can also potentially carry out as a modern approach for the development of HIV-1 and HTLV-1 vaccines. Furthermore, as exosomes are present in most biological fluids, they hold the supreme capacity for clinical usage in the early diagnosis and prognosis of viral infection and associated diseases. Our current knowledge of exosomes' role from virus-infected cells may provide an avenue for efficient retroviruses associated with disease prevention. However, the exact mechanism involved in retroviruses infection/ inflammation remains elusive and related exosomes research will shed light on the mechanisms of pathogenesis.

scholarly journals Relative contribution of free-virus and synaptic transmission to the spread of HIV-1 through target cell populations

2013 ◽  
Vol 9 (1) ◽  
pp. 20121049 ◽  
Author(s):  
Natalia L. Komarova ◽  
Daniela Anghelina ◽  
Igor Voznesensky ◽  
Benjamin Trinité ◽  
David N. Levy ◽  
...  
Keyword(s):  
Synaptic Transmission ◽  
Target Cells ◽  
Free Virus ◽  
Virus Growth ◽  
Relative Contribution ◽  
Immunodeficiency Virus ◽  
Virological Synapses ◽  
Transmission Pathways ◽  
Hiv 1

Human immunodeficiency virus can spread through target cells by transmission of cell-free virus or directly from cell-to-cell via formation of virological synapses. Although cell-to-cell transmission has been described as much more efficient than cell-free infection, the relative contribution of the two transmission pathways to virus growth during multiple rounds of replication remains poorly defined. Here, we fit a mathematical model to previously published and newly generated in vitro data, and determine that free-virus and synaptic transmission contribute approximately equally to the growth of the virus population.

scholarly journals Expression of Nef Downregulates CXCR4, the Major Coreceptor of Human Immunodeficiency Virus, from the Surfaces of Target Cells and Thereby Enhances Resistance to Superinfection

2006 ◽  
Vol 80 (22) ◽  
pp. 11141-11152 ◽  
Author(s):  
Stephanie Venzke ◽  
Nico Michel ◽  
Ina Allespach ◽  
Oliver T. Fackler ◽  
Oliver T. Keppler
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Lymphocytes ◽  
Maximum Level ◽  
Target Cells ◽  
Class I Mhc ◽  
Mhc I ◽  
Immunodeficiency Virus ◽  
Infected Cells ◽  
Stromal Cell Derived Factor ◽  
Hiv 1

ABSTRACT Lentiviral Nef proteins are key factors for pathogenesis and are known to downregulate functionally important molecules, including CD4 and major histocompatibility complex class I (MHC-I), from the surfaces of infected cells. Recently, we demonstrated that Nef reduces cell surface levels of the human immunodeficiency virus type 1 (HIV-1) entry coreceptor CCR5 (N. Michel, I. Allespach, S. Venzke, O. T. Fackler, and O. T. Keppler, Curr. Biol. 15:714-723, 2005). Here, we report that Nef downregulates the second major HIV-1 coreceptor, CXCR4, from the surfaces of HIV-infected primary CD4 T lymphocytes with efficiencies comparable to those of the natural CXCR4 ligand, stromal cell-derived factor-1 alpha. Analysis of a panel of mutants of HIV-1SF2 Nef revealed that the viral protein utilized the same signature motifs for downmodulation of CXCR4 and MHC-I, including the proline-rich motif P73P76P79P82 and the acidic cluster motif E66E67E68E69. Expression of wild-type Nef, but not of specific Nef mutants, resulted in a perinuclear accumulation of the coreceptor. Remarkably, the carboxy terminus of CXCR4, which harbors the classical motifs critical for basal and ligand-induced receptor endocytosis, was dispensable for the Nef-mediated reduction of surface exposure. Functionally, the ability of Nef to simultaneously downmodulate CXCR4 and CD4 correlated with maximum-level protection of Nef-expressing target cells from fusion with cells exposing X4 HIV-1 envelopes. Furthermore, the Nef-mediated downregulation of CXCR4 alone on target T lymphocytes was sufficient to diminish cells' susceptibility to X4 HIV-1 virions at the entry step. The downregulation of chemokine coreceptors is a conserved activity of Nef to modulate infected cells, an important functional consequence of which is an enhanced resistance to HIV superinfection.

scholarly journals Broadly neutralizing antibodies that inhibit HIV-1 cell to cell transmission

2013 ◽  
Vol 210 (13) ◽  
pp. 2813-2821 ◽  
Author(s):  
Marine Malbec ◽  
Françoise Porrot ◽  
Rejane Rua ◽  
Joshua Horwitz ◽  
Florian Klein ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Target Cells ◽  
Type I ◽  
Broadly Neutralizing Antibodies ◽  
Major Mechanism ◽  
Viral Spread ◽  
Cell Transmission ◽  
Cd4 Binding Site ◽  
Virological Synapses ◽  
Hiv 1

The neutralizing activity of anti–HIV-1 antibodies is typically measured in assays where cell-free virions enter reporter cell lines. However, HIV-1 cell to cell transmission is a major mechanism of viral spread, and the effect of the recently described broadly neutralizing antibodies (bNAbs) on this mode of transmission remains unknown. Here we identify a subset of bNAbs that inhibit both cell-free and cell-mediated infection in primary CD4+ lymphocytes. These antibodies target either the CD4-binding site (NIH45-46 and 3BNC60) or the glycan/V3 loop (10-1074 and PGT121) on HIV-1 gp120 and act at low concentrations by inhibiting multiple steps of viral cell to cell transmission. These antibodies accumulate at virological synapses and impair the clustering and fusion of infected and target cells and the transfer of viral material to uninfected T cells. In addition, they block viral cell to cell transmission to plasmacytoid DCs and thereby interfere with type-I IFN production. Thus, only a subset of bNAbs can efficiently prevent HIV-1 cell to cell transmission, and this property should be considered an important characteristic defining antibody potency for therapeutic or prophylactic antiviral strategies.

scholarly journals Simultaneous Cell-to-Cell Transmission of Human Immunodeficiency Virus to Multiple Targets through Polysynapses

2009 ◽  
Vol 83 (12) ◽  
pp. 6234-6246 ◽  
Author(s):  
Dominika Rudnicka ◽  
Jérôme Feldmann ◽  
Françoise Porrot ◽  
Steve Wietgrefe ◽  
Stéphanie Guadagnini ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Supramolecular Organization ◽  
Microtubule Organizing Center ◽  
Multiple Targets ◽  
Gag Proteins ◽  
Immunodeficiency Virus ◽  
Organizing Center ◽  
Infected Cells ◽  
Virological Synapses ◽  
Viral Transfer

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) efficiently propagates through cell-to-cell contacts, which include virological synapses (VS), filopodia, and nanotubes. Here, we quantified and characterized further these diverse modes of contact in lymphocytes. We report that viral transmission mainly occurs across VS and through “polysynapses,” a rosette-like structure formed between one infected cell and multiple adjacent recipients. Polysynapses are characterized by simultaneous HIV clustering and transfer at multiple membrane regions. HIV Gag proteins often adopt a ring-like supramolecular organization at sites of intercellular contacts and colocalize with CD63 tetraspanin and raft components GM1, Thy-1, and CD59. In donor cells engaged in polysynapses, there is no preferential accumulation of Gag proteins at contact sites facing the microtubule organizing center. The LFA-1 adhesion molecule, known to facilitate viral replication, enhances formation of polysynapses. Altogether, our results reveal an underestimated mode of viral transfer through polysynapses. In HIV-infected individuals, these structures, by promoting concomitant infection of multiple targets in the vicinity of infected cells, may facilitate exponential viral growth and escape from immune responses.

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