Several years have passed since the Zika virus (ZIKV) pandemic reoccurred in 2015–2016. However, there is still a lack of proved protective vaccines or effective drugs against ZIKV. The peptide brevinin-2GHk (BR2GK), pertaining to the brevinin-2 family of antimicrobial peptides, has been reported to exhibit only weak antibacterial activity, and its antiviral effects have not been investigated. Thus, we analyzed the effect of BR2GK on ZIKV infection. BR2GK showed significant inhibitory activity in the early and middle stages of ZIKV infection, with negligible cytotoxicity. Furthermore, BR2GK was suggested to bind with ZIKV E protein and disrupt the integrity of the envelope, thus directly inactivating ZIKV. In addition, BR2GK can also penetrate the cell membrane, which may contribute to inhibition of the middle stage of ZIKV infection. BR2GK blocked ZIKV E protein expression with an IC₅₀ of 3.408 ± 0.738 μΜ. In summary, BR2GK was found to be a multi-functional candidate and a potential lead compound for further development of anti-ZIKV drugs.

Background: Zika virus (ZIKV) is an emerging flavivirus that may cause innate microcephaly or neurological disturbances. Yet no antiviral has been approved by FDA against ZIKV infection. It was shown that some unsaturated fatty acids could inactivate enveloped viruses including SARS-CoV-2. However, studies investigating the effect of eicosapentaenoic acid (EPA) on ZIKV infection are lacking. This study aims to evaluate the antiviral effect of EPA against ZIKV and other enveloped viruses.Methods: We first explored the toxicities of EPA in vitro and in vivo. Then we examined the antiviral effect of EPA against ZIKV via cell-based immunodetection, qRT-PCR, Western blotting, and so on. To uncover its antiviral mechanism, we performed assays for virus binding, adsorption and entry, and time-of-addition. RNase digestion and ZIKV NS2B-NS3 protease inhibition assays were also adopted. Finally, we detected its effects on dengue virus (DENV)-2, herpes simplex virus (HSV)-1 and influenza A virus via MTT, Western blotting and qRT-PCR assays.Results: EPA was found to inhibit ZIKV infection in vitro without causing cytotoxicities. EPA exhibited antiviral activity in the early stages of the ZIKV life cycle quickly. Mechanistic experiments showed that EPA disrupted the membrane integrity of viral particles, leading to the release of viral RNA, together with the interruption of ZIKV from binding, adsorption and entry, and ultimately the inhibition of viral proliferation. Furthermore, EPA exerted antiviral effects against DENV-2, HSV-1, and influenza virus, in a dose-dependent manner.Conclusion: These findings suggest that EPA is a promising broad-spectrum antiviral drug candidate.

Zika virus (ZIKV) can traverse the placental barrier, leading to fetal microcephaly and congenital zika syndrome (CZS). The viral E protein mediates host-cell interactions and infection. Here, we demonstrated that cord blood natural killer cell-derived extracellular vesicles (CBNK-EVs) potently inhibit ZIKV infection in vitro without compromising cellular viability. Mechanistically, CBNK-EVs engage ZIKV through ITGB2, a surface-enriched integrin that interacts with the viral E protein, facilitating nanoparticle-virion contact or membrane fusion. This interaction triggers antiviral activity via perforins within extracellular vesicles (EVs), resulting in diminished viral infectivity. Notably, CBNK-EVs not only effectively crossed the placental barrier to protect fetuses from ZIKV-induced pathologies, but also reduced the ZIKV burden in IFN-deficient murine models and decreased CZS incidence and mortality. Additionally, either blockade of ITGB2 with a monoclonal antibody or chelation of Ca²⁺ with EGTA impaired the anti-ZIKV activity of CBNK-EVs. Collectively, our findings identified CBNK-EVs as natural antiviral nanoparticles that play a pivotal role in curbing ZIKV infection and vertical transmission, offering a promising therapeutic strategy against congenital ZIKV-related complications.