s Resveratrol Treatment-induced Nuclear HMGB1 Retention is Critical for Inducing Host Interferon Responses Against Zika Virus

Background: Zika virus (ZIKV) infection is a public health concern and currently there is no specific therapeutic or approved vaccine. Resveratrol (RESV), a natural antiviral compound, has been shown to possess antiviral properties against ZIKV and other viral infections, but the mechanisms of action against ZIKV remain unknown. Objective: This study aimed to investigate the role of the high mobility group box 1 protein (HMGB1) in the underlying anti-ZIKV mechanisms of RESV. Methods: HMGB1 protein expression and ZIKV replication in both the RESV-treated wildtype (WT) and HMGB1-knockdown (shHMGB1) Huh7 cells were analyzed using ELISA, immunofluorescence assay, immunoblot assay, focus-forming assay and qRT-PCR. HMGB1’s role was explored by evaluating the changes in the type-1 interferon (IFN) response genes using the qRT-PCR and immunoblot assays. Results: The treatment of the ZIKV-infected WT Huh7 cells with RESV significantly reduced ZIKV titers by >90% (P < 0.001) at 48 and 72 hr pi in a dose-dependent manner and inhibited ZIKV-induced HMGB1 translocation (P < 0.001), resulting in nuclear HMGB1 accumulation. Compared to the WT Huh7 cells, shHMGB1 Huh7 cells without RESV treatment showed a significant increase in the infectious virus titers and RNA with a maximum rise of 74% (P < 0.001) and 65% (P < 0.01), respectively. RESV treatment of the ZIKV-infected WT Huh7 cells significantly increased the MxA (one of the classical interferon-stimulated genes, ISGs) and IFN-β levels (P < 0.05). The treatment of the infected shHMGB1 Huh7 cells with RESV showed a less effective antiviral response (P > 0.05) and did not cause changes in the expressions of MxA and IFN-β. Conclusion: RESV possesses therapeutic activity against ZIKV infection and the mechanism of action is mainly attributed to HMGB1 nuclear retention, which could upregulate the type-1 IFN and ISGs.