Dengue Virus Targets Nrf2 for NS2B3-Mediated Degradation Leading to Enhanced Oxidative Stress and Viral Replication

Abstract

Dengue virus (DENV) is a mosquito-borne virus that infects upward of 300 million people annually and has the potential to cause fatal hemorrhagic fever and shock. While the parameters contributing to dengue immunopathogenesis remain unclear, the collapse of redox homeostasis and the damage induced by oxidative stress have been correlated with the development of inflammation and progression towards the more severe forms of disease. In the present study, we demonstrate that the accumulation of reactive oxygen species (ROS) late after DENV infection (>24 hpi) resulted from a disruption in the balance between oxidative stress and the Nuclear factor erythroid 2-related factor 2 (Nrf2)-dependent antioxidant response. The DENV NS2B3 protease complex strategically targeted Nrf2 for degradation in a proteolytic-independent manner; rather NS2B3 licensed Nrf2 for lysosomal degradation. Impairment of the Nrf2 regulator by the NS2B3 complex inhibited the antioxidant gene network and contributed to the progressive increase in ROS levels, along with an increased virus replication and inflammatory or apoptotic gene expression. By 24hpi, when increased levels of ROS and antiviral proteins were observed, it appeared that the pro-viral effect of ROS overcame the antiviral effects of the IFN response. Overall, these studies demonstrate that DENV infection disrupts the regulatory interplay between DENV-induced stress responses, Nrf2 anti-oxidant signaling and the host antiviral immune response, thus exacerbating oxidative stress and inflammation in DENV infection. IMPORTANCE Dengue virus (DENV) is a mosquito-borne pathogen that threatens 2.5 billion people in over 100 countries annually. Dengue infection induces a spectrum of clinical symptoms, ranging from classical dengue fever to severe dengue hemorrhagic fever or dengue shock syndrome; however, the complexities of DENV immunopathogenesis remain controversial. Previous studies reported the importance of the transcription factor Nrf2 in the control of the redox homeostasis and antiviral/inflammatory or death responses to DENV. Importantly, production of reactive oxygen species and the subsequent stress response have been linked to the development of inflammation and progression towards the more severe forms of the disease. Here, we demonstrate that DENV uses the NS2B3 protease complex to strategically target Nrf2 for degradation, leading to a progressive increase in oxidative stress, inflammation and cell death in infected cells. This study underlines the pivotal role of the Nrf2 regulatory network in the context of DENV infection.

Keap1 recognizes EIAV early accessory protein Rev to promote antiviral defense

“…Interestingly, some viruses such as Kaposi’s Sarcoma-Associated Herpesvirus (KSHV) infection benefit from Nrf2 activation [41-43]. However, Dengue virus and Respiratory syncytial virus (RSV) infection increases reactive oxygen species (ROS) and induce degradation of Nrf2 by different mechanisms [44-46]. As the key molecule that regulates the Nrf2-ARE pathway, Keap1 binds to Nrf2 to maintain a cellular antioxidant defense homeostasis.…”

Nrf2/Keap1/ARE signaling: Towards specific regulation

“…Other example of Nrf2 activating virus is the Dengue virus, which activates Nrf2 via nuclear translocation and after endoplasmic reticular stress this signaling lead to the Nrf2-mediated TNF-α production which, in turn, contributes to the severity of illness in patients with DENV infection [141] . Recently, Ferrari et al demonstrated that during first 24 h of the DENV infection Nrf2 is activated with increased expression of antioxidant genes, restricted IFN type I response, decreased ROS production and inflammation [142] , thereby limiting antiviral response. Later (24 h–48 h after infection) viral protease NS2B3 cleaves Nrf2, resulting in ROS accumulation and increased inflammation, creating conditions favoring viral replication [142] .…”

Recent Insights Into the Molecular Mechanism of Toll-Like Receptor Response to Dengue Virus Infection

“…A recent study reported a dose-dependent inhibition of DENV replication with (E)-guggulsterone, which stimulates nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated heme oxygenase-1 (HO-1) expression; this expression increased the antiviral IFN response and downstream antiviral gene expression by blocking DENV NS2B/3B protease activity ( Chen et al, 2021 ). However, in an in vitro study, Ferrari et al (2020) showed that the DENV NS2B3 protease complex can target and promote Nrf2 degradation. A recent study revealed that DENV could utilize STAT3 as a proviral factor for its propagation in A549 cells.…”