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HIV-1 cell to cell transfer across an Env-induced, actin-dependent synapse.

Jolly C, Kashefi K, Hollinshead M, Sattentau QJ - J. Exp. Med. (2004)

Bottom Line: Receptor recognition by HIV-1 occurs via interactions between the viral surface envelope glycoprotein (Env), gp120, and CD4 and a chemokine receptor, CCR5 or CXCR4.Recruitment of these membrane molecules into polarized clusters was dependent on Env engagement of CD4 and CXCR4 and required remodelling of the actin cytoskeleton.We propose that receptor engagement by Env directs the rapid, actin-dependent recruitment of HIV receptors and adhesion molecules to the interface, resulting in a stable adhesive junction across which HIV infects the target cell.

View Article: PubMed Central - PubMed

Affiliation: The Sir William Dunn School of Pathology, University of Oxford, UK.

ABSTRACT
Direct cell-cell transfer is an efficient mechanism of viral dissemination within an infected host, and human immunodeficiency virus 1 (HIV-1) can exploit this mode of spread. Receptor recognition by HIV-1 occurs via interactions between the viral surface envelope glycoprotein (Env), gp120, and CD4 and a chemokine receptor, CCR5 or CXCR4. Here, we demonstrate that the binding of CXCR4-using HIV-1-infected effector T cells to primary CD4(+)/CXCR4(+) target T cells results in rapid recruitment to the interface of CD4, CXCR4, talin, and lymphocyte function-associated antigen 1 on the target cell, and of Env and Gag on the effector cell. Recruitment of these membrane molecules into polarized clusters was dependent on Env engagement of CD4 and CXCR4 and required remodelling of the actin cytoskeleton. Transfer of Gag from effector to target cell was observed by 1 h after conjugate formation, was independent of cell-cell fusion, and was probably mediated by directed virion fusion with the target cell. We propose that receptor engagement by Env directs the rapid, actin-dependent recruitment of HIV receptors and adhesion molecules to the interface, resulting in a stable adhesive junction across which HIV infects the target cell.

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Related in: MedlinePlus

Immunoelectron microscopy showing clusters of HIV-1 particles at the synapse. Effector–target conjugates were formed for 1 h and processed for electron microscopy. (A) Low magnification (11,000×) of an ultrathin section through an effector–target cell conjugate. Closely apposed regions of membrane are numbered (1 and 2). Bar, 1 μm. (B) Higher magnification (30,000×) of the interface in the same conjugate. Small arrows highlight 6 nm of gold particles bound to CD4 on the target cell. Large arrows show mature virions associated with the membrane of the target cell, and the asterisk marks a structure resembling a budding virion. Bar, 300 nm.
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fig7: Immunoelectron microscopy showing clusters of HIV-1 particles at the synapse. Effector–target conjugates were formed for 1 h and processed for electron microscopy. (A) Low magnification (11,000×) of an ultrathin section through an effector–target cell conjugate. Closely apposed regions of membrane are numbered (1 and 2). Bar, 1 μm. (B) Higher magnification (30,000×) of the interface in the same conjugate. Small arrows highlight 6 nm of gold particles bound to CD4 on the target cell. Large arrows show mature virions associated with the membrane of the target cell, and the asterisk marks a structure resembling a budding virion. Bar, 300 nm.

Mentions: HIV-1 virions can bud in a directional manner between infected and uninfected cells (3). To investigate whether HIV-1 transfer from effector to target cells might occur in this way, we analyzed conjugates by TEM. Conjugates were formed by mixing equal numbers of effector and target cells at 37°C in the presence of L120. After fixation, cells labeled for CD4 were immunostained with gold particles. Fig. 7 shows the interface formed between an effector and a target cell after 1 h conjugate formation. Two regions of tight apposition between the cell plasma membranes are evident and virions with dense cores are observed at the interface and attached to the target cell membrane. Virions were not observed elsewhere on effector cell membranes, confirming clustering of virions at the interface (Fig. 7 A and not depicted). In Fig. 7 B, a structure resembling a virion budding from the effector cell membrane is shown, and gold particles labeling the target cell membrane are visible. In none of ∼50 conjugates examined by TEM have we observed evidence of endocytic uptake of virions into target cells.


HIV-1 cell to cell transfer across an Env-induced, actin-dependent synapse.

Jolly C, Kashefi K, Hollinshead M, Sattentau QJ - J. Exp. Med. (2004)

Immunoelectron microscopy showing clusters of HIV-1 particles at the synapse. Effector–target conjugates were formed for 1 h and processed for electron microscopy. (A) Low magnification (11,000×) of an ultrathin section through an effector–target cell conjugate. Closely apposed regions of membrane are numbered (1 and 2). Bar, 1 μm. (B) Higher magnification (30,000×) of the interface in the same conjugate. Small arrows highlight 6 nm of gold particles bound to CD4 on the target cell. Large arrows show mature virions associated with the membrane of the target cell, and the asterisk marks a structure resembling a budding virion. Bar, 300 nm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2211771&req=5

fig7: Immunoelectron microscopy showing clusters of HIV-1 particles at the synapse. Effector–target conjugates were formed for 1 h and processed for electron microscopy. (A) Low magnification (11,000×) of an ultrathin section through an effector–target cell conjugate. Closely apposed regions of membrane are numbered (1 and 2). Bar, 1 μm. (B) Higher magnification (30,000×) of the interface in the same conjugate. Small arrows highlight 6 nm of gold particles bound to CD4 on the target cell. Large arrows show mature virions associated with the membrane of the target cell, and the asterisk marks a structure resembling a budding virion. Bar, 300 nm.
Mentions: HIV-1 virions can bud in a directional manner between infected and uninfected cells (3). To investigate whether HIV-1 transfer from effector to target cells might occur in this way, we analyzed conjugates by TEM. Conjugates were formed by mixing equal numbers of effector and target cells at 37°C in the presence of L120. After fixation, cells labeled for CD4 were immunostained with gold particles. Fig. 7 shows the interface formed between an effector and a target cell after 1 h conjugate formation. Two regions of tight apposition between the cell plasma membranes are evident and virions with dense cores are observed at the interface and attached to the target cell membrane. Virions were not observed elsewhere on effector cell membranes, confirming clustering of virions at the interface (Fig. 7 A and not depicted). In Fig. 7 B, a structure resembling a virion budding from the effector cell membrane is shown, and gold particles labeling the target cell membrane are visible. In none of ∼50 conjugates examined by TEM have we observed evidence of endocytic uptake of virions into target cells.

Bottom Line: Receptor recognition by HIV-1 occurs via interactions between the viral surface envelope glycoprotein (Env), gp120, and CD4 and a chemokine receptor, CCR5 or CXCR4.Recruitment of these membrane molecules into polarized clusters was dependent on Env engagement of CD4 and CXCR4 and required remodelling of the actin cytoskeleton.We propose that receptor engagement by Env directs the rapid, actin-dependent recruitment of HIV receptors and adhesion molecules to the interface, resulting in a stable adhesive junction across which HIV infects the target cell.

View Article: PubMed Central - PubMed

Affiliation: The Sir William Dunn School of Pathology, University of Oxford, UK.

ABSTRACT
Direct cell-cell transfer is an efficient mechanism of viral dissemination within an infected host, and human immunodeficiency virus 1 (HIV-1) can exploit this mode of spread. Receptor recognition by HIV-1 occurs via interactions between the viral surface envelope glycoprotein (Env), gp120, and CD4 and a chemokine receptor, CCR5 or CXCR4. Here, we demonstrate that the binding of CXCR4-using HIV-1-infected effector T cells to primary CD4(+)/CXCR4(+) target T cells results in rapid recruitment to the interface of CD4, CXCR4, talin, and lymphocyte function-associated antigen 1 on the target cell, and of Env and Gag on the effector cell. Recruitment of these membrane molecules into polarized clusters was dependent on Env engagement of CD4 and CXCR4 and required remodelling of the actin cytoskeleton. Transfer of Gag from effector to target cell was observed by 1 h after conjugate formation, was independent of cell-cell fusion, and was probably mediated by directed virion fusion with the target cell. We propose that receptor engagement by Env directs the rapid, actin-dependent recruitment of HIV receptors and adhesion molecules to the interface, resulting in a stable adhesive junction across which HIV infects the target cell.

Show MeSH
Related in: MedlinePlus