Mary L Hasek, Jonathan D Steckbeck, Berthony Deslouches, Jodi K Craigo and Ronald C Montelaro
In recent decades, efforts have been made to rationally design antimicrobial peptides (AMPs) for use as alternative antimicrobial therapeutics. The de novo engineered cationic antimicrobial peptide (eCAP) WLBU2 is a 24-residue peptide composed of arginine, tryptophan, and valine computationally sequenced to form an optimized amphipathic helix. Antimicrobial activity of WLBU2 is predicted to transpire through peptide interaction with lipid membranes leading to bilayer disruption. Antibacterial activity of WLBU2 has been demonstrated against a widerange of antibiotic resistant Gram-positive and Gram-negative bacteria. Natural antimicrobial peptides have been shown to inactivate enveloped viruses, albeit at higher peptide concentrations than required for bacterial killing. While viral envelopes do not have the same negative surface charge presumed to be the basis for antibacterial activity of WLBU2, most mammalian virus membranes are enriched for cholesterol relative to host cells. Based on this structural feature, WLBU2 was modified by addition of cholesterol recognition amino acid consensus (CRAC) motifs to increase antiviral activity against enveloped mammalian viruses. The CRAC-modified WLBU2 peptides were tested against human immunodeficiency virus (HIV), influenza A, and dengue virus (DENV) to assess antiviral activity against viruses with markedly different levels of surface lipid exposure and against mammalian cells to assess potential cytotoxicity. Antiviral activity was enhanced by the CRAC motif and demonstrated the highest efficacy against DENV and lowest against HIV, inverse to the level of surface membrane exposure. These studies reveal for the first time an unexpected range of engineered peptide activity against a broad group of different target viruses with vastly different membrane composures and indicate the ability of CRAC motif modification to enhance antiviral activity.