Quantifying lipid contents in enveloped virus particles with plasmonic nanoparticles

Area of Science:

• Biophysics
• Virology
• Nanotechnology

Background:

• Host-derived lipids, including phosphatidylserine (PS) and monosialotetrahexosylganglioside (GM1), are incorporated into enveloped virus membranes.
• These lipids influence critical viral processes such as attachment, entry, and spread.
• Accurate quantification of these lipids is essential for understanding their functional contribution to virus infectivity.

Purpose of the Study:

• To introduce a novel gold nanoparticle (NP) binding assay for quantifying relative concentrations of PS and GM1 in enveloped virus-like particles (VLPs).
• To enable quantitative analysis of viral membrane lipid composition using small sample sizes (less than 3 × 10^6 particles).

Main Methods:

• Development of a gold nanoparticle (NP) binding assay utilizing scattering intensity and resonance wavelength.
• Measurement of NP densities via plasmon coupling to determine relative lipid concentrations in VLP membranes.
• Calibration of the assay using unilamellar liposomes with known PS or GM1 concentrations for correlation with absolute lipid content.

Main Results:

• The assay successfully probed relative PS and GM1 concentrations in HIV-1 and Ebola VLPs.
• Significant differences in VLP membrane lipid composition were observed depending on their intracellular assembly site.
• The study demonstrates the potential for optical quantification of lipid concentrations in virus particles at physiological titers.

Conclusions:

• The gold nanoparticle binding assay provides a sensitive method for characterizing viral membrane lipid composition.
• Variations in lipid content reflect different VLP assembly pathways.
• This technique offers a pathway for optical quantification of lipids in virus particles, crucial for virology research.