MIB1 and viral infectious disease: Since the E3 ligases Mind Bomb 1 and 2 (MIB1 and MIB2) have been recently shown to promote the attachment of K63-linked ubiquitin chains to TBK1 following virus infection [12] and that this modification is required for TBK1-induced gene expression and kinase activation [40], we hypothesized that Optn may act as an inhibitor of the antiviral signaling pathway by targeting a deubiquitinase to TBK1.