Structure–Function Insights into Frog Skin Peptides Reveal Potent Inhibition of West Nile Virus Entry

Over the past five decades, the emergence and re-emergence of multiple flaviviruses have triggered significant global outbreaks, posing serious threats to public health. Among them, West Nile virus (WNV) is a major cause of mosquito-borne illness, typically presenting as an acute systemic febrile disease and, in some cases, progressing to the central nervous system involvement. No specific antiviral therapies or effective vaccines are available for WNV infections. In this context, antimicrobial peptides (AMPs) with antiviral properties—known as antiviral peptides (AVPs)—have gained attention as potential therapeutic agents due to their ability to interfere with various stages of the viral life cycle. Two frog-derived melittin-like peptides, AR-23 and RV-23, were synthesized and purified, and their hemolytic activity was assessed on human erythrocytes. Antiviral activity against WNV was evaluated in Vero cells using cytopathic effect reduction assays and real-time PCR quantification of viral RNA. Time-of-addition experiments were conducted to explore the stage of viral inhibition. In silico molecular docking studies were performed to examine interactions between the peptides and the viral E glycoprotein. Both peptides displayed strong antiviral effects during the early phases of infection, likely through direct interaction with viral particles and disruption of virus–host interactions. Compared with melittin, AR-23 and RV-23 showed greater efficacy and lower cytotoxicity, highlighting their potential as promising therapeutic candidates for flavivirus infections.