A Dengue Virus Type 2 (DENV-2) NS4B-Interacting Host Factor, SERP1, Reduces DENV-2 Production by Suppressing Viral RNA Replication.

Jia-Ni Tian,Chiu-Kai Chuang,Ren-Huang Wu,Chiung-Tong Chen,Andrew Yueh,Chi-Chen Yang,Ming-Han Tsai

doi:10.3390/v11090787

Abstract

Host cells infected with dengue virus (DENV) often trigger endoplasmic reticulum (ER) stress, a key process that allows viral reproduction, without killing the host cells until the late stage of the virus life-cycle. However, little is known regarding which DENV viral proteins interact with the ER machinery to support viral replication. In this study, we identified and characterized a novel host factor, stress-associated ER protein 1 (SERP1), which interacts with the DENV type 2 (DENV-2) NS4B protein by several assays, for example, yeast two-hybrid, subcellular localization, NanoBiT complementation, and co-immunoprecipitation. A drastic increase (34.5-fold) in the SERP1 gene expression was observed in the DENV-2-infected or replicon-transfected Huh7.5 cells. The SERP1 overexpression inhibited viral yields (37-fold) in the DENV-2-infected Huh7.5 cells. In contrast, shRNAi-knockdown and the knockout of SERP1 increased the viral yields (3.4- and 16-fold, respectively) in DENV-2-infected HEK-293 and Huh7.5 cells, respectively. DENV-2 viral RNA replication was severely reduced in stable SERP1-expressing Huh7.5 cells transfected with DENV-2 replicon plasmids. The overexpression of DENV-2 NS4B alleviated the inhibitory effect of SERP1 on DENV-2 RNA replication. Taking these results together, we hypothesized that SERP1 may serve as an antiviral player during ER stress to restrict DENV-2 infection. Our studies revealed novel anti-DENV drug targets that may facilitate anti-DENV drug discovery.

Highlights

dengue virus (DENV) infection is a common arbovirus illness in humans [1]
The results of the present study suggest that stress-associated ER protein 1 (SERP1) is an antiviral protein, and that the interaction of dengue virus type 2 (DENV-2) NS4B with SERP1 may counteract the antagonistic effect of SERP1 on the DENV-2 life-cycle
Ten-fold serial yeast dilutions were spotted onto nonselective plates (-Trp–Leu; lacking tryptophan and leucine) and selective plates (-Trp–Leu–His–Ade; lacking tryptophan, leucine, histidine, and adenine) for the detection of protein–protein interactions. (B) Dengue virus type 2 (DENV-2) NS4B colocalized with SERP1 and the endoplasmic reticulum (ER) marker calnexin

Summary

Introduction

DENV infection is a common arbovirus illness in humans [1]. DENV has four serotypes (one to four) and belongs to the genus Flavivirus within the family Flaviviridae. In addition to DENV, other viruses in the genus Flavivirus, such as the West Nile virus (WNV), Japanese encephalitis virus (JEV), yellow fever virus, and tick-borne encephalitis virus, are pathogens of humans and animals. After acute dengue viral infection, patients often develop fever, rash, headache, muscle and joint pain, and nausea [2]. More than 3.5 billion people are at risk for DENV infection. It has been estimated that each year, up to 96 million of the 390 million DENV infections in the world are symptomatic [1]

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Conclusion