Suppression of cGAS- and RIG-I-mediated innate immune signaling by Epstein-Barr virus deubiquitinase BPLF1

Abstract

Epstein-Barr virus (EBV) has developed effective strategies to evade host innate immune responses. Here we reported on mitigation of type I interferon (IFN) production by EBV deubiquitinase (DUB) BPLF1 through cGAS-STING and RIG-I-MAVS pathways. The two naturally occurring forms of BPLF1 exerted potent suppressive effect on cGAS-STING-, RIG-I- and TBK1-induced IFN production. The observed suppression was reversed when DUB domain of BPLF1 was rendered catalytically inactive. The DUB activity of BPLF1 also facilitated EBV infection by counteracting cGAS-STING- and TBK1-mediated antiviral defense. BPLF1 associated with STING to act as an effective DUB targeting its K63-, K48- and K27-linked ubiquitin moieties. BPLF1 also catalyzed removal of K63- and K48-linked ubiquitin chains on TBK1 kinase. The DUB activity of BPLF1 was required for its suppression of TBK1-induced IRF3 dimerization. Importantly, in cells stably carrying EBV genome that encodes a catalytically inactive BPLF1, the virus failed to suppress type I IFN production upon activation of cGAS and STING. This study demonstrated IFN antagonism of BPLF1 mediated through DUB-dependent deubiquitination of STING and TBK1 leading to suppression of cGAS-STING and RIG-I-MAVS signaling.

Nsp1 facilitates SARS-CoV-2 replication through calcineurin-NFAT signaling

“…Dual luciferase reporter assay, co-immunoprecipitation, and Western blotting were performed as described ( 60 ).…”

STINGing Defenses: Unmasking the Mechanisms of DNA Oncovirus-Mediated Immune Escape

“…Removing of all types of ubiquitin moieties on TBK1, leading to inactivation of the kinase inhibition of TBK1-induced IRF3 dimerization HEK293 cells overexpressing BPLF1, cGAS, STING, TBK1 and IRF3 [188] Murine gammaherpesvirus 68…”

“…During the lytic phase of EBV infection, a large tegument protein named BPLF1, which exhibits deubiquitinase activity, is expressed [ 186 , 187 ]. BPLF1 was found to bind directly to STING and remove all types of ubiquitin moieties on the molecule [ 188 ]. The absence of K63-linked ubiquitination would suppress STING activation and downstream IFN production [ 115 ].…”

“…This results in the outcompetition of IRF3 for TBK1 binding and subsequent inhibition of TBK1-induced IRF3 activation [ 194 ]. EBV large tegument protein BPLF1, which was found to disrupt STING activity through deubiquitination, also removes all types of ubiquitin moieties on TBK1, leading to inactivation of the kinase and inhibition of TBK1-induced IRF3 dimerization [ 188 ]. In addition, increased levels of HPV16 E7 have been associated with a decrease in STING-dependent phosphorylation of TBK1 [ 160 ].…”

Contribution of Epstein–Barr Virus Lytic Proteins to Cancer Hallmarks and Implications from Other Oncoviruses

“…It binds to cGAS to inhibit its enzymatic activity and blocks cGAMP synthesis [ 63 ]. BPLF1 also deubiquitinates STING and TANK-binding kinase 1 (TBK1) and suppresses cGAS-STING and retinoic acid-inducible gene I (RIG-I)-MAVS pathways [ 65 ]. Figure 2 displays the schematic diagram of the role of EBV lytic proteins in modulating immune responses related to oncogenesis.…”