Study of the inhibition capacity of an 18-mer peptide domain of GBV-C virus on gp41-FP HIV-1 activity

Abstract

The peptide sequence (175-192) RFPFHRCGAGPKLTKDLE (P59) of the E2 envelope protein of GB virus C (GBV-C) has been proved to decrease cellular membrane fusion and interfere with the HIV-1 infectivity in a dose-dependent manner. Based on these previous results, the main objective of this study was to deepen in the physicochemical aspects involved in this interaction. First, we analyzed the surface activity of P59 at the air-water interface as well as its interaction with zwitterionic or negatively charged lipid monolayers. Then we performed the same experiments with mixtures of P59/gp41-FP. Studies on lipid monolayers helped us to understand the lipid-peptide interaction and the influence of phospholipids on peptide penetration into lipid media. On another hand, studies with lipid bilayers showed that P59 decreased gp41-FP binding to anionic Large Unilamellar Vesicles. Results can be attributed to the differences in morphology of the peptides, as observed by Atomic Force Microscopy. When P59 and gp41-FP were incubated together, annular structures of about 200 nm in diameter appeared on the mica surface, thus indicating a peptide-peptide interaction. All these results confirm the gp41-FP-P59 interaction and thus support the hypothesis that gp41-FP is inhibited by P59.

Role of GB virus C in modulating HIV disease

“…Synthetic peptides of the GBV-C E2 domain have been shown to interact with the HIV-1 fusion protein and to modify its conformation [142]. This indicates a possible alteration of the interaction of HIV-1 fusion protein with the cell membrane decreasing cellular membrane fusion in a dose-dependent manner [143,144]. Furthermore, Mohr et al have found that naturally occurring GBV-C E2 antibodies from HIV-negative individuals and experimentally induced GBV-C E2 antibodies neutralize HIV-1 infection in vitro by inhibit of HIV attachment, but do not inhibiting HIV entry following attachment [145].…”

“…(5) Furthermore, secretion of RANTES, MIP-1α and MIP-1β – natural ligands of the other HIV co-receptor CCR5 – is elevated during GBV-C co-infection leading to lower surface expression of CCR5 [131,137]. (6) Direct inhibition of HIV entry by GBV-C E2 protein has been proposed and interaction of GBV-C E2 with the HIV-1 fusion protein has been shown [141–144]. (7) Furthermore, GBV-C E2 Abs have been demonstrated to neutralize HIV-1 infection by inhibition of viral attachment [145].…”

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

“…Our group has been performing in vitro physical and chemical studies with GBV-C peptide sequences that have proven to be effective as potential inhibitors of HIV-1 FP, yielding results on the interaction of the virus with several sequences of interest [8][9][10][11][12]. HIV-1 FP and GBV-C peptides have amphiphilic properties that allow them to undergo self-assembly in aqueous solution to form various nanoscale architectures.…”

“…Surface behaviour at the air-water interface [15][16][17], and in peptide-lipid binding assays [11,18,19], leakage assays, fluorescence anisotropy or fluorescence resonance energy transfer studies [20,21] have each been applied to find a correlate between the capacity to inhibit HIV-1 FP in vitro and in vivo during cell-cell fusion inhibition studies [10,15]. In addition, topographical characterisation of model membranes showing the changes caused by HIV-1 FP or GBV-C peptides in various mixtures have been obtained by fluorescence microscopy (FM) and atomic force microscopy (AFM) [22,23].…”

“…A mixture of dimyristoyl phosphatidylcholine (DMPC) and dimyristoyl phosphatidylserine (DMPS) at a ratio of 3:2 was used for the membrane composition. Phosphatidylcholine (PC) is the major component of the outer leaflet of uninfected cells, and phosphatidylserine (PS) is a hallmark of programmed cell death, it is expressed at elevated levels in HIV-1-infected T cells or macrophages because of the association of apoptosis with the progression of AIDS [11,23].…”