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Imaging of HIV-1 Envelope-induced Virological Synapse and Signaling on Synthetic Lipid Bilayers
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Imaging of HIV-1 Envelope-induced Virological Synapse and Signaling on Synthetic Lipid Bilayers

Published on: March 8, 2012

Evidence for budding of human immunodeficiency virus type 1 selectively from glycolipid-enriched membrane lipid rafts

D H Nguyen1, J E Hildreth

  • 1Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.

Journal of Virology
|March 9, 2000
PubMed

Insights

Human immunodeficiency virus type 1 (HIV-1) buds through lipid rafts, incorporating host cell GPI-linked proteins like Thy-1 and CD59 into its envelope. HIV-1 avoids CD45, a transmembrane phosphatase, during this budding process.

Area of Science:

  • Cell Biology
  • Virology
  • Immunology

Background:

  • Lipid rafts are membrane microdomains enriched in cholesterol and sphingolipids, crucial for T-cell signaling.
  • Glycosylphosphatidylinositol (GPI)-linked proteins like Thy-1 and CD59 are sequestered in lipid rafts.
  • CD45, a transmembrane phosphatase, is excluded from these lipid raft domains.

Purpose of the Study:

  • To investigate the role of lipid rafts in human immunodeficiency virus type 1 (HIV-1) assembly and budding.
  • To determine the incorporation of host cell membrane proteins, particularly lipid raft components, into HIV-1 virions.

Main Methods:

  • Confocal fluorescence microscopy to visualize the colocalization of HIV-1 proteins with lipid raft markers and CD45 in infected Jurkat cells.
  • Dot immunoassay of Triton X-100-extracted membrane fractions to analyze the presence of HIV-1 proteins in detergent-resistant lipid rafts.
  • Metabolic labeling of HIV Gag protein to quantify its enrichment in lipid rafts.

Main Results:

  • HIV-1 particles produced by infected T-cells incorporated GPI-linked proteins (Thy-1, CD59) and GM1 ganglioside, which are lipid raft components.
  • CD45 was poorly incorporated into HIV-1 particles, consistent with its exclusion from lipid rafts.
  • HIV-1 proteins (p17 matrix, gp41, Gag) were found in detergent-resistant fractions, indicating their association with lipid rafts.
  • HIV-1 proteins colocalized with lipid raft markers in uropods of infected cells, while CD45 did not.

Conclusions:

  • HIV-1 virions bud through lipid rafts, incorporating host cell cholesterol, sphingolipids, and GPI-linked proteins into the viral envelope.
  • Preferential sorting of HIV Gag to lipid rafts likely facilitates the budding process.
  • The exclusion of CD45 from HIV-1 virions suggests a selective incorporation mechanism during budding.

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