In vitro assembly of a viral envelope

Abstract

Viruses such as influenza and Ebola are enveloped in lipid bilayers annexed from host cells and containing glycoproteins essential for the infection process. At the molecular level little is known about the assembly process in terms of physical interactions between the lipids and glycoproteins. In this paper we assemble HIV glycoproteins in lipid vesicles in order to examine envelope assembly, a process that is usually only executed under control of a host cell. Using atomic force microscopy it was possible to observe fusion of individual envelope like particles, and contrast this with the behaviour of lipid vesicles without envelope glycoproteins. It was found that the inclusion of glycoproteins caused the vesicles to distort and that the subsequent fusion "footprint" with a lipid bilayer was related to the envelopes' unique morphology. This non-spherical morphology suggests that the presence of a viral capsid may be essential for the stability of an enveloped virus. Interactions between trans-membrane gp41 and gp120, the spikes protruding from a virion, were examined using supported lipid bilayers. Interactions between the gp120 and membrane-located gp41 resulted in the assembly of unusual molecular wires, one molecule in height and with a zigzag arrangement of gp120 molecules. In this work we have shown that purely physical/chemical interactions have dramatic effects on glycoprotein/lipid assembly and should be considered in the development of virus based technologies such as virosomes.

Osmotic stress and pore nucleation in charged biological nanoshells and capsids

“…These building blocks are collectively combined to form an envelope that protects and transports the viral genetic material [53][54][55][56][57][58]. Viral capsids display a wide range of topologies [37,[59][60][61][62][63][64], and can be further coated with membranes or protein sheets [56,[65][66][67][68]. The key aspects that describe the rich topology of these objects have been long ago rationalized in the seminal work of Clasper and Klug [59,69].…”

Detection of lipid-induced structural changes of the Marburg virus matrix protein VP40 using hydrogen/deuterium exchange-mass spectrometry

“…EBOV and MARV are lipid-enveloped viruses and their lipid envelope is extracted from the host cell plasma membrane when the nascent viral particles bud out from the host cell (5). The matrix protein VP40 is a peripheral protein located beneath the lipid envelope providing structural stability to the viral particle and a protein matrix layer to facilitate budding of virions from the plasma membrane.…”

Topography design in model membranes: Where biology meets physics

“…Flat synthetic membranes are a powerful tool to investigate how the biophysics of lipid–lipid interactions contributes to the assembly of complex biological structures. 117–119 Advances in the engineering of structural features in solid supports is allowing the generation of ever more complex spatial or curvature patterned bilayers, thus creating more realistic mimics of cellular membranes. SLBs with rough surfaces facilitate the systematic dissection of the interplay between curvature and lipid sorting and crucially, how these physical properties are coupled and controlled in a complex biological process.…”