Mechanism of an Amphipathic α-Helical Peptide’s Antiviral Activity Involves Size-Dependent Virus Particle Lysis

Abstract

The N-terminal region of the hepatitis C virus (HCV) nonstructural protein NS5A contains an amphipathic alpha-helix that is necessary and sufficient for NS5A membrane association. A synthetic peptide (AH) comprising this amphipathic helix is able to lyse lipid vesicles that serve as a model system for virus particles. Based on quartz crystal microbalance-dissipation (QCM-D) experiments, the degree of vesicle rupturing was found to be inversely related to vesicle size, with maximal activity in the size range of several medically important viruses. In order to confirm and further study vesicle rupture, dynamic light scattering (DLS) and atomic force microscopy (AFM) experiments were also performed. The size dependence of vesicle rupturing helps explain the peptide's observed effect on the infectivity of a wide range of viruses. Further, in vitro studies demonstrated that AH peptide treatment significantly decreased the infectivity of HCV particles. Thus, the AH peptide might be used to rupture HCV particles extra-corporally (for HCV prevention) and within infected individuals (for HCV therapy).

Model Membrane Platforms for Biomedicine: Case Study on Antiviral Drug Development

“…In this outlook, we introduce areas where we envision engineering strategies may further aid antiviral drug development. By assembling an in situ assay to predict virus particle rupture [40][41][42][43], the work reviewed here has established a cost-effective tool to rapidly screen and functionally characterize antiviral drug candidates in minutes rather than days. Based on this preliminary format, the system can be improved by increasing sensitivity to reduce the amount of peptide material required and/or adapting the signal response to a more readily high-throughput measurement technique.…”

“…As a case study example of a viral pathogen target, we have selected the hepatitis C virus (HCV) and discuss how engineering strategies identified a previously unknown functional activity encoded within the HCV nonstructural 5A (NS5A) protein. By employing a model membrane platform to mimic the host cell membrane interface upon which viral genome replication occurs, a striking ability to lyse lipid vesicles was discovered within the NS5A N-terminal amphipathic, a-helix (AH) [40][41][42][43].…”

“…Because lipid vesicles also serve as a simplified model for the lipid envelope of virus particles, mechanistic studies predicted that a range of medically important viruses might be susceptible to rupturing treatment with a synthetic AH peptide [41]. Importantly, these predictions were tested and validated by molecular virology experiments which demonstrated AH peptide has broad-spectrum antiviral activity against HCV, HIV, herpes simplex virus, and dengue virus, as well as many more deadly pathogens [44][45][46].…”

Rupture of zwitterionic lipid vesicles by an amphipathic, α-helical peptide: Indirect effects of sensor surface and implications for experimental analysis

“…Using quartz crystal microbalance with dissipation (QCM-D) monitoring, it was identified that AH peptide first adsorbs onto the vesicle surface, before destabilizing vesicles and causing vesicle rupture to form a planar bilayer [15]. In order to more clearly understand the mechanism of vesicle destabilization, simultaneous monitoring of the interaction between intact vesicles and AH peptide was performed with the QCM-D and reflectometry techniques [16]. It was identified that AH peptide binding causes an increase in solvent mass associated with the adsorbed vesicle layer prior to rupture.…”

Synthetic analogues of bovine bactenecin dodecapeptide reduce herpes simplex virus type 2 infectivity in mice

“…These peptides often rely on their amphiphatic structure for their antiviral activity (Jenssen et al, 2004a;Yasin et al, 2000). Examples of synthetic antiviral peptides include both microbe-derived and hostderived peptide analogues, and these peptides can interfere with several medically important enveloped viruses (Cho et al, 2009;Mohan et al, 2010). The potential of using synthetic anti-microbial peptides (AMPs) against HSV is underscored by studies showing that synthetic derivatives of both human beta-defensins and frog magainins as well as several different families of synthetic peptides have anti-HSV activity in vitro (Egal et al, 1999;Jenssen et al, 2004a;Krepstakies et al, 2012;Luganini et al, 2011;Scudiero et al, 2010).…”