LIPID DOMAINS IN LB FILMS AND GIANT VESICLES TO STUDY GBV-C PEPTIDES INTERACTION IN THE CONTEXT OF HIV-1 FP INHIBITION AT MEMBRANES

Lipid domains have been obtained using Langmuir-Blodgett films (LBs) and giant unilamellar vesicles (GUVs). Three membranes compositions were chosen, the canonical DOPC: DOPS (3:2)/SM/CHOL (1:1:1), the more physiological one: DOPC: DOPS (3:2)/SM/CHOL (2:1:1) and another one with more phospholipid content: DOPC: DOPS (3:2)/SM/CHOL (3:1:1). All systems were well characterized by π-A isotherms. As the (SM/CHOL (1:1:1)) concentration increases, the membrane fluidity decreases as demonstrated by the compressibility modulus and area per molecule values. Lipid domains morphology was examined by confocal microscopy. Images corroborated the presence of two liquid immiscible phases: a phospholipid-enriched Ld phase and a sphingomyelin enriched Lo phase. GBV-C peptide membrane interaction was examined using P6-2VIR576 peptide and tryptophan (Trp) fluorescence spectroscopy. P6-2VIR576 increased the fluidity of lipid monolayers and bilayers making hard to distinguish the Ld/Lo edges. Its capacity to inhibit the action of the fusion peptide of human immunodeficiency virus (HIV-1 FP) on membranes has been demonstrated.