A study of HIV-1 FP inhibition by GBV-C peptides using lipid nano-assemblies

• P 45 GBV-C peptide inhibits HIV-1 FP activity at membrane level in vitro.
• P45 + HIV-1 FP mixture produces dissolution of lipid condensed domains at high pressure.
• AFM reveals arrowhead structures when P45 peptide interact with DMPC:DMPS (3:2) film.

Langmuir–Blodgett films (LBs) and supported lipid bilayers (SLBs) of dimyristoylphosphatidylcholine (DMPC)–dimyristoylphosphatidylserine (DMPS) (3:2) were used to investigate the way that a GBV-C peptide (P45) inhibits the immunodeficiency human virus fusion peptide (HIV-1 FP) action at membrane level. Supported lipid bilayers (SLBs) were prepared by direct adsorption of a liposomal dispersion on solid mica slides and Langmuir–Blodgett films (LBs) by a deposition of a monolayer onto mica solid surface at different compression pressures. The behaviour of P45, HIV-1 FP and a mixture of P45 and HIV-1 FP (1:1) were monitored in the two phospholipid membrane models by fluorescence microscopy (FM) and atomic force microscopy (AFM). Experiments with SLBs confirmed that P45 inhibited HIV-1 FP action in vitro. LBs obtained at 10 and 25 mN m−1 confirmed different lipid interactions for DMPC/DMPS (3:2) in combination with either P45 (8:2), HIV-1 FP (8:2), or P45 and HIV-1 FP (8:1:1). The P45 peptide was confirmed to modulate the action of HIV-1 FP. Furthermore, FM and AFM images showed that HIV-1 FP had a pressure-independent membrane-level behaviour when compared with P45 and the P45 + HIV-1 FP (1:1) mixture. This mixture also had dramatic effects on the appearance of liquid expanded (LE)–liquid condensed (LC) phase coexistence as shown by FM and AFM.

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