INMI1 Zika Virus NS4B Antagonizes the Interferon Signaling by Suppressing STAT1 Phosphorylation

Abstract

The evasion of the Interferon response has important implications in Zika virus (ZIKV) disease. Mutations in ZIKV viral protein NS4B, associated with modulation of the interferon (IFN) system, have been linked to increased pathogenicity in animal models. In this study, we unravel ZIKV NS4B as antagonist of the IFN signaling cascade. Firstly, we reported the genomic characterization of NS4B isolated from a strain of the 2016 outbreak, ZIKV Brazil/2016/INMI1, and we predicted its membrane topology. Secondly, we analyzed its phylogenetic correlation with other flaviviruses, finding a high similarity with dengue virus 2 (DEN2) strains; in particular, the highest conservation was found when NS4B was aligned with the IFN inhibitory domain of DEN2 NS4B. Hence, we asked whether ZIKV NS4B was also able to inhibit the IFN signaling cascade, as reported for DEN2 NS4B. Our results showed that ZIKV NS4B was able to strongly inhibit the IFN stimulated response element and the IFN-γ-activated site transcription, blocking IFN-I/-II responses. mRNA expression levels of the IFN stimulated genes ISG15 and OAS1 were also strongly reduced in presence of NS4B. We found that the viral protein was acting by suppressing the STAT1 phosphorylation and consequently blocking the nuclear transport of both STAT1 and STAT2.

Dengue virus NS4B protein as a target for developing antivirals

“…Dengue NS4B was first demonstrated to block IFN signaling during viral infection ( Muñoz-Jordán et al., 2003 ). The effect of NS4B on IFN through suppressing STAT1 phosphorylation upon ZIKV infection was also confirmed recently ( Fanunza et al., 2021 ). The two membrane association regions (pTMD1 and pTMD2) are critical for the inhibitory function of NS4B on IFN signaling ( Munoz-Jordan et al., 2005 ).…”

“…The replication complex of DENV on ER membrane contains viral proteins and RNA. The roles of NS4B in the replication complex are achieved through protein-protein interactions ( Wang et al., 2015 ; Xie et al., 2015 ; Tian et al., 2019 ; Fanunza et al., 2021 ; Lu et al., 2021 ). Researchers have identified several viral and host proteins that exhibited molecular interactions with NS4B.…”

Single-cell transcriptomics and network pharmacology reveal therapeutic targets of Jianpi Yiqi Bugan Yishen decoction in immune cell subsets of children with myasthenia gravis

“…Our results showed the target genes STAT1, MCL1, and FOS were upregulated in all cell subsets, and their abundance changed significantly from the normal control and pre-treatment group compared to their levels after treatment, indicating their importance in the remission of MG. STATs are also downstream targets of Janus tyrosine kinases, and the Janus tyrosine kinase/STAT signal transduction pathway mediates a variety of immune-related cytokine signals ( 23 , 24 ). Among these, the type-I interferon (IFN-I) signaling pathway depends on the induction of STAT1 ( 25 ), and IFN-I has been found to increase the risk of MG ( 26 ). Patients with MG exhibit high levels of IFN-I and expression of various IFN-I-induced genes in the thymus ( 27 ), and targeted STAT1 therapy may hold promise for its treatment.…”

Structures and Dynamics of Dengue Virus Nonstructural Membrane Proteins

“…The 2K peptide preceding NS4B can be released through cleavage by a host signalase, and its C-terminus release is achieved via the NS2B-NS3 protease. NS4B does not possess any enzymatic activities and plays important roles in viral replication and affects host immunity through protein-protein interactions [7,46,[127][128][129].…”