Objective: This study aimed to determine the antiviral activity of ten Philippine medicinal plants against Zika virus (ZIKV). Methods: Lyophilized aqueous plant extracts were used for cell cytotoxicity and virus inhibition assays. The therapeutic index was computed from the 50% cytotoxic concentration (CC50) and 50% effective concentration (EC50) values. Plant metabolites were also identified using mass spectroscopy. An in-silico screening of these metabolites was done using ZIKV enzymes and the Axl protein in human microglial cells as target proteins, followed by the ranking of binding energy scores to generate a hypothesis on the possible mechanism of antiviral action. Results: The plants that demonstrated the highest therapeutic index were Momordica charantia, Psidium guajava, Vitex negundo, and Blumea balsamifera. The majority of the metabolites present in the aqueous extracts were saponin, terpenes and terpenoids, and anthocyanin. Further, in-silico docking results showed a higher binding affinity for viral replication proteins compared to the viral envelope protein. Conclusion The crude aqueous extracts of M. charantia, P. guajava, V. negundo, and B. balsamifera were the most potent candidate antiviral therapies against ZIKV among the ten plants tested. Meanwhile, the in-silico results suggested that the metabolites possibly employ an intracellular mechanism for the observed antiviral activity.
Herbal Medicine

Objective: To identify unique immunogenic epitopes of Zika virus non-structural 1 (NS1) antigen and produce immunoglobulin Y (IgY) for potential use in he diagnosis of of Zika virus infection. Methods: Immunogenic epitopes were identified using in silico B-cell epitope prediction. A synthetic peptide analog of the predicted epitope was used to induce antipeptide IgY production in hens which was purified using affinity chromatography. Presence of purified IgY and its binding specificity were performed by gel electrophoresis and ELISA, respectively. Results: Out of the nine continuous epitopes identified, the sequence at position 193-208 (LKVREDYSLECDPAVI) was selected and used to produce anti-peptide IgY. The produced IgY was found to bind to the synthetic analog of the Zika virus NS1 immunogenic epitope but not to other flaviviruses and random peptides from other pathogens. Conclusions: In this study, we identified an immunogenic epitope unique to Zika virus that can be used to develop a serodiagnostic tool that specifically detect Zika virus infection.