Zebrafish sirt7 Negatively Regulates Antiviral Responses by Attenuating Phosphorylation of irf3 and irf7 Independent of Its Enzymatic Activity.

Sirt7 is one member of the sirtuin family proteins with NAD (NAD+)-dependent histone deacetylase activity. In this study, we report that zebrafish sirt7 is induced upon viral infection, and overexpression of sirt7 suppresses cellular antiviral responses. Disruption of sirt7 in zebrafish increases the survival rate upon spring viremia of carp virus infection. Further assays indicate that sirt7 interacts with irf3 and irf7 and attenuates phosphorylation of irf3 and irf7 by preventing tbk1 binding to irf3 and irf7. In addition, the enzymatic activity of sirt7 is not required for sirt7 to repress IFN-1 activation. To our knowledge, this study provides novel insights into sirt7 function and sheds new light on the regulation of irf3 and irf7 by attenuating phosphorylation.