USP18 Mediates Interferon Resistance of Dengue Virus Infection.

Haiyan Ye,Bin Li,Yujia Li,Min Yao,Xiaoqiong Duan,Lan Kang,Limin Chen,Shilin Li

doi:10.3389/fmicb.2021.682380

Abstract

Previous studies demonstrated that dengue virus (DENV) infection developed resistance to type-I interferons (IFNα/β). The underlying mechanism remains unclear. USP18 is a negative regulator of IFNα/β signaling, and its expression level is significantly increased following DENV infection in cell lines and patients’ blood. Our previous study revealed that increased USP18 expression contributed to the IFN-α resistance of Hepatitis C Virus (HCV). However, the role of USP18 in DENV replication and resistance to IFN-α is elusive. In this current study, we aimed to explore the role of USP18 in DENV-2 replication and resistance to IFN-α. The level of USP18 was up-regulated by plasmid transfection and down-regulated by siRNA transfection in Hela cells. USP18, IFN-α, IFN-β expression, and DENV-2 replication were monitored by qRT-PCR and Western blot. The activation of the Jak/STAT signaling pathway was assessed at three levels: p-STAT1/p-STAT2 (Western blot), interferon-stimulated response element (ISRE) activity (Dual-luciferase assay), and interferon-stimulated genes (ISGs) expression (qRT-PCR). Our data showed that DENV-2 infection increased USP18 expression in Hela cells. USP18 overexpression promoted DENV-2 replication, while USP18 silence inhibited DENV-2 replication. Silence of USP18 potentiated the anti-DENV-2 activity of IFN-α through activation of the IFN-α-mediated Jak/STAT signaling pathway as shown by increased expression of p-STAT1/p-STAT2, enhanced ISRE activity, and elevated expression of some ISGs. Our data indicated that USP18 induced by DENV-2 infection is a critical host factor utilized by DENV-2 to confer antagonism on IFN-α.

Highlights

Dengue virus (DENV), a positive-strand RNA virus, is a member of the arthropod-borne Flaviviridae family of viruses; It consists of four serotypes (DENV-1, dengue virus (DENV)-2, DENV-3, and DENV-4) and is predominantly transmitted by the bites of infected mosquitoes of the genus Aedes (Guzman and Harris, 2015)
Since clinical data showed that patients infected with DENV during the early febrile period contain high levels of type I interferons in the serum (Kurane et al, 1993; Becquart et al, 2010), we examined the expression of IFN-α and IFN-β in DENV-2-infected Hela cells
Since Ubiquitin-specific protease 18 (USP18) is a negative regulator of the IFN-I signaling and increased USP18 expression contributed to IFN resistance of Hepatitis C Virus (HCV) (Malakhova et al, 2006; Randall et al, 2006), we examined whether silencing of USP18 could rescue IFN-α resistance of DENV-2

Summary

Introduction

Dengue virus (DENV), a positive-strand RNA virus, is a member of the arthropod-borne Flaviviridae family of viruses; It consists of four serotypes (DENV-1, DENV-2, DENV-3, and DENV-4) and is predominantly transmitted by the bites of infected mosquitoes of the genus Aedes (Guzman and Harris, 2015). It is estimated that DENV infection occurred in over 100 countries and regions, affecting more than. Innate immunity is the body’s first line of defense to fight against various virus infections. DENV infection triggers innate immune responses through activating the toll-like receptor-3 (TLR3), retinoic acid-inducible gene–I (RIG-I), and melanoma differentiation-associated gene-5 (MDA5) pathways (Nasirudeen et al, 2011; Chazal et al, 2018), Which subsequently induces the host innate immunity, mainly the increased production of type-I interferons (IFN-I, mainly IFN-A, and IFN-β). IFNα/β binds to the IFN-I receptor (IFNAR) and activates the downstream Jak/STAT signaling pathway to produce a few hundred Interferon Stimulated Genes (ISGs) to limit viral replication/production (Coldbeck-Shackley et al, 2020)

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