Limits...
Human T-lymphotropic virus-1 visualized at the virological synapse by electron tomography.

Majorovits E, Nejmeddine M, Tanaka Y, Taylor GP, Fuller SD, Bangham CR - PLoS ONE (2008)

Bottom Line: The synaptic clefts are surrounded by the tightly apposed plasma membranes of the two cells.HTLV-1 virions can contact the recipient cell membrane before detaching from the infected cell.The results show that the HTLV-1 virological synapse that forms spontaneously between lymphocytes of HTLV-1 infected individuals allows direct cell-cell transmission of the virus by triggered, directional release of enveloped HTLV-1 particles into confined intercellular spaces.

View Article: PubMed Central - PubMed

Affiliation: Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.

ABSTRACT
Human T-lymphotropic virus 1 (HTLV-1) is transmitted directly between cells via an organized cell-cell contact called a virological synapse (VS). The VS has been studied by light microscopy, but the ultrastructure of the VS and the nature of the transmitted viral particle have remained unknown. Cell-free enveloped virions of HTLV-1 are undetectable in the serum of individuals infected with the human T-lymphotropic virus 1 (HTLV-1) and during in vitro culture of naturally infected lymphocytes. However, the viral envelope protein is required for infectivity of HTLV-1, suggesting that complete, enveloped HTLV-1 virions are transferred across the synapse. Here, we use electron tomography combined with immunostaining of viral protein to demonstrate the presence of enveloped HTLV-1 particles within the VS formed between naturally infected lymphocytes. We show in 3D that HTLV-1 particles can be detected in multiple synaptic clefts at different locations simultaneously within the same VS. The synaptic clefts are surrounded by the tightly apposed plasma membranes of the two cells. HTLV-1 virions can contact the recipient cell membrane before detaching from the infected cell. The results show that the HTLV-1 virological synapse that forms spontaneously between lymphocytes of HTLV-1 infected individuals allows direct cell-cell transmission of the virus by triggered, directional release of enveloped HTLV-1 particles into confined intercellular spaces.

Show MeSH

Related in: MedlinePlus

Polarization of mitochondria and microtubule organization centre of the HTLV-1 infected cell towards the target cell.A,B Virological synapses (VS) formed between naturally HTLV-1 infected CD4+ T cells (PBMCs) and autologous uninfected CD4+ target cells as shown in Movies S6–S7 and S3, S4, S5, respectively. HTLV-1 particles in the synaptic cleft can be identified by the black anti-Gag p19 labelling (white arrow heads). Mitochondria (black arrows) are located in the vicinity of the synapse; most mitochondria (black arrows) are polarized towards the VS. Also the MTOC is polarized to the synapse as revealed by one of the two centrioles (white arrow in B). Scale bars: A and B 500 nm.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2386264&req=5

pone-0002251-g002: Polarization of mitochondria and microtubule organization centre of the HTLV-1 infected cell towards the target cell.A,B Virological synapses (VS) formed between naturally HTLV-1 infected CD4+ T cells (PBMCs) and autologous uninfected CD4+ target cells as shown in Movies S6–S7 and S3, S4, S5, respectively. HTLV-1 particles in the synaptic cleft can be identified by the black anti-Gag p19 labelling (white arrow heads). Mitochondria (black arrows) are located in the vicinity of the synapse; most mitochondria (black arrows) are polarized towards the VS. Also the MTOC is polarized to the synapse as revealed by one of the two centrioles (white arrow in B). Scale bars: A and B 500 nm.

Mentions: The 2D measured length of the cell-cell contacts was greater in conjugates between HTLV-1 infected CD4+ T cells (mean, 2.8 µm; max., 5.6 µm) than in normal CD4+ T cell conjugates (mean, 1.9 µm; max., 2.5 µm) (Figure 1C). In a sample of 1084 CD4+ T cells stained for HTLV-1 Gag protein we found 7 (0.65%) cell-cell conjugates with anti-Gag labelling at the VS (Figure 1D,E,F, arrows). HTLV-1 particles were identified by their close resemblance in size and morphology to the HTLV-1 particles produced by in vitro cell lines, described by Miyauchi et al [19], and by positive staining for Gag protein; such particles were not observed in uninfected cells or conjugates. Many HTLV-1 particles were almost entirely surrounded by the adjacent cell membranes (Figure 1D); others were contained in a larger synaptic pocket (Figure 1E). In several cases, viral particles were in contact with the two adjacent cell membranes simultaneously (Figure 1D,F). Mitochondria frequently accumulated in the infected cell in the vicinity of the VS (Movies S1, Movie S3, Movie S6; Figure 2A,B), consistent with the polarization of the MTOC to the VS [2], [14], [15] (Figure 1G, arrow pointing at centriole), as seen at the immunological synapse [20]–[22].


Human T-lymphotropic virus-1 visualized at the virological synapse by electron tomography.

Majorovits E, Nejmeddine M, Tanaka Y, Taylor GP, Fuller SD, Bangham CR - PLoS ONE (2008)

Polarization of mitochondria and microtubule organization centre of the HTLV-1 infected cell towards the target cell.A,B Virological synapses (VS) formed between naturally HTLV-1 infected CD4+ T cells (PBMCs) and autologous uninfected CD4+ target cells as shown in Movies S6–S7 and S3, S4, S5, respectively. HTLV-1 particles in the synaptic cleft can be identified by the black anti-Gag p19 labelling (white arrow heads). Mitochondria (black arrows) are located in the vicinity of the synapse; most mitochondria (black arrows) are polarized towards the VS. Also the MTOC is polarized to the synapse as revealed by one of the two centrioles (white arrow in B). Scale bars: A and B 500 nm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2386264&req=5

pone-0002251-g002: Polarization of mitochondria and microtubule organization centre of the HTLV-1 infected cell towards the target cell.A,B Virological synapses (VS) formed between naturally HTLV-1 infected CD4+ T cells (PBMCs) and autologous uninfected CD4+ target cells as shown in Movies S6–S7 and S3, S4, S5, respectively. HTLV-1 particles in the synaptic cleft can be identified by the black anti-Gag p19 labelling (white arrow heads). Mitochondria (black arrows) are located in the vicinity of the synapse; most mitochondria (black arrows) are polarized towards the VS. Also the MTOC is polarized to the synapse as revealed by one of the two centrioles (white arrow in B). Scale bars: A and B 500 nm.
Mentions: The 2D measured length of the cell-cell contacts was greater in conjugates between HTLV-1 infected CD4+ T cells (mean, 2.8 µm; max., 5.6 µm) than in normal CD4+ T cell conjugates (mean, 1.9 µm; max., 2.5 µm) (Figure 1C). In a sample of 1084 CD4+ T cells stained for HTLV-1 Gag protein we found 7 (0.65%) cell-cell conjugates with anti-Gag labelling at the VS (Figure 1D,E,F, arrows). HTLV-1 particles were identified by their close resemblance in size and morphology to the HTLV-1 particles produced by in vitro cell lines, described by Miyauchi et al [19], and by positive staining for Gag protein; such particles were not observed in uninfected cells or conjugates. Many HTLV-1 particles were almost entirely surrounded by the adjacent cell membranes (Figure 1D); others were contained in a larger synaptic pocket (Figure 1E). In several cases, viral particles were in contact with the two adjacent cell membranes simultaneously (Figure 1D,F). Mitochondria frequently accumulated in the infected cell in the vicinity of the VS (Movies S1, Movie S3, Movie S6; Figure 2A,B), consistent with the polarization of the MTOC to the VS [2], [14], [15] (Figure 1G, arrow pointing at centriole), as seen at the immunological synapse [20]–[22].

Bottom Line: The synaptic clefts are surrounded by the tightly apposed plasma membranes of the two cells.HTLV-1 virions can contact the recipient cell membrane before detaching from the infected cell.The results show that the HTLV-1 virological synapse that forms spontaneously between lymphocytes of HTLV-1 infected individuals allows direct cell-cell transmission of the virus by triggered, directional release of enveloped HTLV-1 particles into confined intercellular spaces.

View Article: PubMed Central - PubMed

Affiliation: Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.

ABSTRACT
Human T-lymphotropic virus 1 (HTLV-1) is transmitted directly between cells via an organized cell-cell contact called a virological synapse (VS). The VS has been studied by light microscopy, but the ultrastructure of the VS and the nature of the transmitted viral particle have remained unknown. Cell-free enveloped virions of HTLV-1 are undetectable in the serum of individuals infected with the human T-lymphotropic virus 1 (HTLV-1) and during in vitro culture of naturally infected lymphocytes. However, the viral envelope protein is required for infectivity of HTLV-1, suggesting that complete, enveloped HTLV-1 virions are transferred across the synapse. Here, we use electron tomography combined with immunostaining of viral protein to demonstrate the presence of enveloped HTLV-1 particles within the VS formed between naturally infected lymphocytes. We show in 3D that HTLV-1 particles can be detected in multiple synaptic clefts at different locations simultaneously within the same VS. The synaptic clefts are surrounded by the tightly apposed plasma membranes of the two cells. HTLV-1 virions can contact the recipient cell membrane before detaching from the infected cell. The results show that the HTLV-1 virological synapse that forms spontaneously between lymphocytes of HTLV-1 infected individuals allows direct cell-cell transmission of the virus by triggered, directional release of enveloped HTLV-1 particles into confined intercellular spaces.

Show MeSH
Related in: MedlinePlus