Unveiling the antiviral mechanism of A4S7: a synthetic antimicrobial peptide targeting dengue and other mosquito-borne enveloped virus infections.

Abstract

Dengue virus (DENV), an enveloped mosquito-borne flavivirus, is the causative agent of dengue and prevalent in tropical and subtropical regions. Severe cases can progress to dengue hemorrhagic fever or shock syndrome, posing significant public health challenges. In the absence of specific antiviral drugs, antimicrobial peptides (AMPs) have emerged as promising therapeutic agents against DENV due to their broad-spectrum antibacterial and antiviral properties. This study investigated the synthetic AMP A4S7, which effectively inhibited DENV-2 RNA and protein expression and reduced viral progeny production at specified concentrations without exhibiting cytotoxicity in Vero cells. Time-of-addition assays indicated that A4S7 might exert antiviral effects during early stages of infection. Binding assays further demonstrated that A4S7 interfered with DENV-2 binding to cellular membrane receptors, supported by molecular docking and FOPPR analyses, which revealed a direct interaction between A4S7 and the DENV-2 envelope protein. Moreover, A4S7 displayed antiviral activity in DENV-2-infected human cell lines, including U2OS, HMC3, and IMR-32 cells. Notably, the α-helical structure of A4S7 was found to be crucial for its antiviral activity. Furthermore, combining A4S7 with late-stage inhibitors such as ivermectin or favipiravir resulted in superior antiviral efficacy compared with their respective monotherapies. Importantly, A4S7 also exhibited antiviral activity against other enveloped viruses, including Zika virus (ZIKV) and Sindbis virus (SINV), but showed no inhibitory effects against non-enveloped viruses such as enterovirus 71 (EV71) and adenovirus. These findings underscore the potential of A4S7 as a promising candidate for the treatment of dengue and other enveloped viral infections.