Identification of brevinin-1EMa-derived stapled peptides as broad-spectrum virus entry blockers

Highlights: • Stapled brevinin peptide analogs possess both antiviral and antibacterial activities. • Enveloped viruses are more susceptible to their antiviral actions than non-enveloped viruses. • Their main antiviral mechanisms might involve viral particle aggregation and resultant neutralization of viral infectivity. • Stabilization of their helical structures by stapling approach increases the resistance to protease-mediated digestion. Based on the previously reported 13-residue antibacterial peptide analog, brevinin-1EMa (FLGWLFKVASKVL, peptide B), we attempted to design a novel class of antiviral peptides. For this goal, we synthesized three peptides with different stapling positions (B–2S, B–8S, and B–5S). The most active antiviral peptide with the specific stapling position (B–5S) was further modified in combination with either cysteine (B–5S3C, B–5S7C, and B–5S10C) or hydrophilic amino acid substitution (Bsub and Bsub-5S). Overall, B, B–5S, and Bsub-5S peptides showed superior antiviral activities against enveloped viruses such as retrovirus, lentivirus, hepatitis C virus, and herpes simplex virus with EC₅₀ values of 1–5 μM. Murine norovirus, a non-enveloped virus, was not susceptible to the virucidal actions of these peptides, suggesting the virus membrane disruption as their main antiviral mechanisms of action. We believe that these three novel peptides could serve as promising candidates for further development of membrane-targeting antiviral drugs in the future.