Antiviral and anti-inflammatory activity of natural compounds against Japanese encephalitis virus via inhibition of NS5 protein and regulation of key immune and inflammatory signaling pathways

Japanese encephalitis virus (JEV) is the foremost cause of viral encephalitis in Southeast Asia and Australia leading to approximately 68 000 clinical cases and about 13 600-20 400 deaths annually. Vaccination is not completely sure and safe. Despite this, no specific antiviral has been available or approved for JEV infection yet and treatment is generally symptomatic. Therefore, this study aims to examine the antiviral activity of natural compounds against JEV proteins. The antiviral activity of natural compounds was investigated via molecular docking, cytopathic effect (CPE) inhibition assay, western blotting, and indirect immunofluorescence assay. Physiochemical, pharmacokinetics, and toxicity analysis were evaluated for the safety and efficacy of natural compounds. Network pharmacology-based approaches have been used to study the molecular mechanisms of drug-target interactions. Molecular docking results suggested that the NS5 protein of JEV is the major target for natural compounds. Network pharmacology-based analysis revealed that these drugs majorly target IL6, AKT1, tumor necrosis factor (TNF), and PTGS2 to regulate key immune and inflammatory pathways such as nuclear factor kappa B, PI3K-Akt, and TNF signaling, during JEV infection. Our in vitro results show that among the natural compounds, curcumin provides the highest protection against JEV infection via reducing the JEV-induced CPE (IC50 = 5.90 +/- 0.44 mu M/mL), and reduces the expression of NS5 protein, IL6, AKT1, TNF-alpha, and PTGS2. However, other natural compounds also provide protection to some extent but their efficacy is lower compared to curcumin. Therefore, this study shows that natural compounds, mainly curcumin, may offer novel therapeutic avenues for the treatment of JEV via inhibiting key viral proteins and regulating crucial host pathways involved in JEV replication.