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Glycosphingolipid-functionalized nanoparticles recapitulate CD169-dependent HIV-1 uptake and trafficking in dendritic cells.

Yu X, Feizpour A, Ramirez NG, Wu L, Akiyama H, Xu F, Gummuluru S, Reinhard BM - Nat Commun (2014)

Bottom Line: This distribution is reminiscent of CD169-dependent HIV-1 sequestration in mature DCs.Our results highlight GM3-CD169 binding as a gp120-independent signal for sequestration and preservation of HIV-1 infectivity.They also indicate that plasmonic AVNs offer improved features over liposome-based systems and represent a versatile tool for probing specific virus-cell interactions.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry and The Photonics Center, Boston University, Boston, Massachusetts 02215, USA.

ABSTRACT
Ganglioside GM3, a host-derived glycosphingolipid incorporated in the membrane of human immunodeficiency virus-1 (HIV-1) viral particles, mediates interactions between HIV-1 and Siglec1/CD169, a protein expressed on dendritic cells (DCs). Such interactions, which seem to be independent of viral envelope glycoprotein gp120, are poorly understood. Here we develop a model system consisting of self-assembled artificial virus nanoparticles (AVNs) that are free of viral glycoproteins or other host-derived glycolipids and glycoproteins. These plasmonic AVNs contain a membrane of defined composition wrapped around a solid metal core. GM3-containing AVNs are captured by CD169-expressing HeLa cells or mature DCs, and are sequestered within non-lysosomal tetraspanin-positive compartments. This distribution is reminiscent of CD169-dependent HIV-1 sequestration in mature DCs. Our results highlight GM3-CD169 binding as a gp120-independent signal for sequestration and preservation of HIV-1 infectivity. They also indicate that plasmonic AVNs offer improved features over liposome-based systems and represent a versatile tool for probing specific virus-cell interactions.

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Design of AVNs. (a) Scheme of HIV-1 structure. HIV-1 is composed of a host derived lipid bilayer membrane wrapped around a protein matrix core that contains the viral RNA. Major lipid components of the viral membrane are included. The viral membrane contains additional lipids, including GM3, albeit with significantly lower concentration. Another membrane component is the virus-encoded glycoprotein gp120. (b) Scheme of minimalistic artificial model systems, AVN1 (left) and AVN2 (right). Both AVNs are assembled from 80nm Au NP cores and comprise a self-assembled lipid membrane. AVN1 contains a lipid bilayer, whereas AVN2 contains a lipid monolayer anchored in a self-assembled octadecanethiol layer. The thiol covalently attaches to the NP surface.
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Figure 1: Design of AVNs. (a) Scheme of HIV-1 structure. HIV-1 is composed of a host derived lipid bilayer membrane wrapped around a protein matrix core that contains the viral RNA. Major lipid components of the viral membrane are included. The viral membrane contains additional lipids, including GM3, albeit with significantly lower concentration. Another membrane component is the virus-encoded glycoprotein gp120. (b) Scheme of minimalistic artificial model systems, AVN1 (left) and AVN2 (right). Both AVNs are assembled from 80nm Au NP cores and comprise a self-assembled lipid membrane. AVN1 contains a lipid bilayer, whereas AVN2 contains a lipid monolayer anchored in a self-assembled octadecanethiol layer. The thiol covalently attaches to the NP surface.

Mentions: HIV-1 particle assembly and budding can occur upon expression of Gag alone in the absence of other viral proteins in host cells. The mature virus particle has a typical size between 120 – 150 nm,34,35 contains ~2500 Gag molecules, and is wrapped in a lipid bilayer that the virus acquires from the plasma membrane during budding from the host cell (reviewed in ref36). The Gag polyprotein is proteolytically cleaved into six structural proteins, matrix (MA), nucleocapsid (NC), capsid (CA), p6 and two spacer proteins, SP1 and SP2 during the virus maturation step.37 Schematic illustrations of the mature virus structure containing the MA protein-enclosed CA shell with the NC-coated viral RNA and the AVN models to mimic it are shown in Fig. 1a and b, respectively. Our AVN design is based on a self-assembled lipid layer around an 80 nm diameter noble metal NP that serves as analogue of the lipid enclosed core formed by association of basic amino acid residues in MA with the inner leaflet of the phosphatidylinositol (PI) 4,5-bisphosphate [PI(4,5)P2] enriched lipid bilayer.36 The lipid layer emulates the virus membrane but is entirely free of proteins and can be engineered with a defined lipid composition, ligand density, and controllable surface charge. In this work we are particularly interested in GM3 containing AVNs for a selective investigation of GM3 interactions with CD169 under well-defined conditions in the absence of potential interferents. We chose gold (Au) as core material since it provides the assembled AVNs with mechanical stiffness38,39 and, at the same time, allows high contrast optical imaging in optical, electron, and x-ray microscopy.40,41 The optical response of spherical Au NPs is dominated by localized surface plasmon resonances (LSPRs) in the visible range of the electromagnetic spectrum.42 A resonant excitation of the LSPR in an 80 nm Au NP is associated with a scattering cross-sections of approximately σ ≈ 2.3×10−10 cm2.43 This huge elastic scattering efficiency, which is orders of magnitude larger than conventional fluorescence cross-sections, facilitates single particle detection entirely free from blinking or bleaching in conventional darkfield microscopy.41,44 Their unique photophysical stability together with their programmable surface properties make Au NPs the core of choice for AVNs in optical studies.


Glycosphingolipid-functionalized nanoparticles recapitulate CD169-dependent HIV-1 uptake and trafficking in dendritic cells.

Yu X, Feizpour A, Ramirez NG, Wu L, Akiyama H, Xu F, Gummuluru S, Reinhard BM - Nat Commun (2014)

Design of AVNs. (a) Scheme of HIV-1 structure. HIV-1 is composed of a host derived lipid bilayer membrane wrapped around a protein matrix core that contains the viral RNA. Major lipid components of the viral membrane are included. The viral membrane contains additional lipids, including GM3, albeit with significantly lower concentration. Another membrane component is the virus-encoded glycoprotein gp120. (b) Scheme of minimalistic artificial model systems, AVN1 (left) and AVN2 (right). Both AVNs are assembled from 80nm Au NP cores and comprise a self-assembled lipid membrane. AVN1 contains a lipid bilayer, whereas AVN2 contains a lipid monolayer anchored in a self-assembled octadecanethiol layer. The thiol covalently attaches to the NP surface.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4109413&req=5

Figure 1: Design of AVNs. (a) Scheme of HIV-1 structure. HIV-1 is composed of a host derived lipid bilayer membrane wrapped around a protein matrix core that contains the viral RNA. Major lipid components of the viral membrane are included. The viral membrane contains additional lipids, including GM3, albeit with significantly lower concentration. Another membrane component is the virus-encoded glycoprotein gp120. (b) Scheme of minimalistic artificial model systems, AVN1 (left) and AVN2 (right). Both AVNs are assembled from 80nm Au NP cores and comprise a self-assembled lipid membrane. AVN1 contains a lipid bilayer, whereas AVN2 contains a lipid monolayer anchored in a self-assembled octadecanethiol layer. The thiol covalently attaches to the NP surface.
Mentions: HIV-1 particle assembly and budding can occur upon expression of Gag alone in the absence of other viral proteins in host cells. The mature virus particle has a typical size between 120 – 150 nm,34,35 contains ~2500 Gag molecules, and is wrapped in a lipid bilayer that the virus acquires from the plasma membrane during budding from the host cell (reviewed in ref36). The Gag polyprotein is proteolytically cleaved into six structural proteins, matrix (MA), nucleocapsid (NC), capsid (CA), p6 and two spacer proteins, SP1 and SP2 during the virus maturation step.37 Schematic illustrations of the mature virus structure containing the MA protein-enclosed CA shell with the NC-coated viral RNA and the AVN models to mimic it are shown in Fig. 1a and b, respectively. Our AVN design is based on a self-assembled lipid layer around an 80 nm diameter noble metal NP that serves as analogue of the lipid enclosed core formed by association of basic amino acid residues in MA with the inner leaflet of the phosphatidylinositol (PI) 4,5-bisphosphate [PI(4,5)P2] enriched lipid bilayer.36 The lipid layer emulates the virus membrane but is entirely free of proteins and can be engineered with a defined lipid composition, ligand density, and controllable surface charge. In this work we are particularly interested in GM3 containing AVNs for a selective investigation of GM3 interactions with CD169 under well-defined conditions in the absence of potential interferents. We chose gold (Au) as core material since it provides the assembled AVNs with mechanical stiffness38,39 and, at the same time, allows high contrast optical imaging in optical, electron, and x-ray microscopy.40,41 The optical response of spherical Au NPs is dominated by localized surface plasmon resonances (LSPRs) in the visible range of the electromagnetic spectrum.42 A resonant excitation of the LSPR in an 80 nm Au NP is associated with a scattering cross-sections of approximately σ ≈ 2.3×10−10 cm2.43 This huge elastic scattering efficiency, which is orders of magnitude larger than conventional fluorescence cross-sections, facilitates single particle detection entirely free from blinking or bleaching in conventional darkfield microscopy.41,44 Their unique photophysical stability together with their programmable surface properties make Au NPs the core of choice for AVNs in optical studies.

Bottom Line: This distribution is reminiscent of CD169-dependent HIV-1 sequestration in mature DCs.Our results highlight GM3-CD169 binding as a gp120-independent signal for sequestration and preservation of HIV-1 infectivity.They also indicate that plasmonic AVNs offer improved features over liposome-based systems and represent a versatile tool for probing specific virus-cell interactions.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry and The Photonics Center, Boston University, Boston, Massachusetts 02215, USA.

ABSTRACT
Ganglioside GM3, a host-derived glycosphingolipid incorporated in the membrane of human immunodeficiency virus-1 (HIV-1) viral particles, mediates interactions between HIV-1 and Siglec1/CD169, a protein expressed on dendritic cells (DCs). Such interactions, which seem to be independent of viral envelope glycoprotein gp120, are poorly understood. Here we develop a model system consisting of self-assembled artificial virus nanoparticles (AVNs) that are free of viral glycoproteins or other host-derived glycolipids and glycoproteins. These plasmonic AVNs contain a membrane of defined composition wrapped around a solid metal core. GM3-containing AVNs are captured by CD169-expressing HeLa cells or mature DCs, and are sequestered within non-lysosomal tetraspanin-positive compartments. This distribution is reminiscent of CD169-dependent HIV-1 sequestration in mature DCs. Our results highlight GM3-CD169 binding as a gp120-independent signal for sequestration and preservation of HIV-1 infectivity. They also indicate that plasmonic AVNs offer improved features over liposome-based systems and represent a versatile tool for probing specific virus-cell interactions.

Show MeSH
Related in: MedlinePlus