Inhibition of the IFN-α JAK/STAT Pathway by MERS-CoV and SARS-CoV-1 Proteins in Human Epithelial Cells (original) (raw)
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2021
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of the coronavirus disease-19 (COVID-19) pandemic, was identified in late 2019 and went on to cause over 3.3 million deaths in 15 months. To date, targeted antiviral interventions against COVID-19 are limited. The spectrum of SARS-CoV-2 infection ranges from asymptomatic to fatal disease. However, the reasons for varying outcomes to SARS-CoV-2 infection are yet to be elucidated. Here we show that an endogenously activated interferon lambda (IFNλ) pathway leads to resistance against SARS-CoV-2 infection. Using a well-differentiated primary nasal epithelial cell (WD-PNEC) model from multiple adult donors, we discovered that susceptibility to SARS-CoV-2 infection, but not respiratory syncytial virus (RSV) infection, varied. One of four donors was resistant to SARS-CoV-2 infection. High baseline IFNλ expression levels and associated interferon stimulated genes correlated with resistance to SARS-CoV-2 infection. Inhi...
Pin-pointing the key hubs in the IFN-γ pathway responding to SARS-CoV-2 infection
ABSTRACTInterferon gamma may be a potential adjuvant immunotherapy for COVID-19 patients. In this work, we assessed gene expression profiles associated with the IFN-γ pathway in response to SARS-CoV-2 infection. Employing a case-control study from SARS-CoV-2 positive and negative patients, we identified IFN-γ-associated pathways to be enriched in positive patients. Bioinformatics analyses showed upregulation ofMAP2K6, CBL, RUNX3, STAT1andJAK2in COVID-19 positive vs. negative patients. A positive correlation was observed betweenSTAT1/JAK2, which varied alongside the patient’s viral load. Expression ofMX1, MX2, ISG15andOAS1(4 well-known IFN-stimulated genes (ISGs)) displayed upregulation in COVID-19 positive vs. negative patients. Integrative analyses showcased higher levels of ISGs which were associated with increased viral load andSTAT1/JAK2expression. Confirmation of ISGs up-regulation was performedin vitrousing the A549 lung cell line treated with Poly(I:C), a synthetic analog of ...
Roles and functions of SARS-CoV-2 proteins in host immune evasion
Frontiers in Immunology, 2022
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) evades the host immune system through a variety of regulatory mechanisms. The genome of SARS-CoV-2 encodes 16 non-structural proteins (NSPs), four structural proteins, and nine accessory proteins that play indispensable roles to suppress the production and signaling of type I and III interferons (IFNs). In this review, we discussed the functions and the underlying mechanisms of different proteins of SARS-CoV-2 that evade the host immune system by suppressing the IFN-b production and TANK-binding kinase 1 (TBK1)/interferon regulatory factor 3 (IRF3)/signal transducer and activator of transcription (STAT)1 and STAT2 phosphorylation. We also described different viral proteins inhibiting the nuclear translocation of IRF3, nuclear factor-kB (NF-kB), and STATs. To date, the following proteins of SARS-CoV-2 including NSP1, NSP6, NSP8, NSP12, NSP13, NSP14, NSP15, open reading frame (ORF)3a, ORF6, ORF8, ORF9b, ORF10, and Membrane (M) protein have been well studied. However, the detailed mechanisms of immune evasion by NSP5, ORF3b, ORF9c, and Nucleocapsid (N) proteins are not well elucidated. Additionally, we also elaborated the perspectives of SARS-CoV-2 proteins.
2020
SUMMARYType I interferons (IFNs) are our first line of defence against a virus. Protein over-expression studies have suggested the ability of SARS-CoV-2 proteins to block IFN responses. Emerging data also suggest that timing and extent of IFN production is associated with manifestation of COVID-19 severity. In spite of progress in understanding how SARS-CoV-2 activates antiviral responses, mechanistic studies into wildtype SARS-CoV-2-mediated induction and inhibition of human type I IFN responses are lacking. Here we demonstrate that SARS-CoV-2 infection induces a mild type I IFN response in vitro and in moderate cases of COVID-19. In vitro stimulation of type I IFN expression and signaling in human airway epithelial cells is associated with activation of canonical transcriptions factors, and SARS-CoV-2 is unable to inhibit exogenous induction of these responses. Our data demonstrate that SARS-CoV-2 is not adept in blocking type I IFN responses and provide support for ongoing IFN cl...
2021
Interferons (IFN) are antiviral cytokines that mitigate the effects of invading viruses early on during the infection process. SARS‐CoV and MERS induce weak IFN responses; hence, the clinical trials which included recombi‐ nant IFN accompanied with other antiviral drugs exhibited improved results in terms of shortening the duration of illness. The aim of the present study was to evaluate the type I IFN response in COVID‐19 patients to determine whether it is sufficient to eliminate or reduce the severity of the infection, and whether it can be recommended as a potential therapy. Total RNA samples were converted to cDNA and used as templates to evaluate the gene expression levels of IFN regula‐ tory factor (IRF)3 and IFN‐β in COVID‐19 patients or control. The results showed that IRF3 gene expression was upregulated ~250‐fold compared with the negative samples. In contrast, IFN‐β expression increased slightly in COVID‐19 patients. Consistent with other coronaviruses, such as SARS‐CoV ...
The Journal of general virology, 2012
STAT1-deficient mice are more susceptible to infection with severe acute respiratory syndrome coronavirus (SARS-CoV) than type I interferon (IFN) receptor-deficient mice. We used mice lacking functional receptors for both type I and type III IFN (double knockout, dKO) to evaluate the possibility that type III IFN plays a decisive role in SARS-CoV protection. We found that viral peak titres in lungs of dKO and STAT1-deficient mice were similar, but significantly higher than in wild-type mice. The kinetics of viral clearance from the lung were also comparable in dKO and STAT1-deficient mice. Surprisingly, however, infected dKO mice remained healthy, whereas infected STAT1-deficient mice developed liver pathology and eventually succumbed to neurological disease. Our data suggest that the failure of STAT1-deficient mice to control initial SARS-CoV replication efficiently in the lung is due to impaired type I and type III IFN signalling, whereas the failure to control subsequent systemic viral spread is due to unrelated defects in STAT1-deficient mice.
SARS-CoV-2 Non-Structural Proteins and Their Roles in Host Immune Evasion
Viruses, 2022
Coronavirus disease 2019 (COVID-19) has caused an unprecedented global crisis and continues to threaten public health. The etiological agent of this devastating pandemic outbreak is the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). COVID-19 is characterized by delayed immune responses, followed by exaggerated inflammatory responses. It is well-established that the interferon (IFN) and JAK/STAT signaling pathways constitute the first line of defense against viral and bacterial infections. To achieve viral replication, numerous viruses are able to antagonize or hijack these signaling pathways to attain productive infection, including SARS-CoV-2. Multiple studies document the roles of several non-structural proteins (NSPs) of SARS-CoV-2 that facilitate the establishment of viral replication in host cells via immune escape. In this review, we summarize and highlight the functions and characteristics of SARS-CoV-2 NSPs that confer host immune evasion. The molecular mechanisms mediating immune evasion and the related potential therapeutic strategies for controlling the COVID-19 pandemic are also discussed.
Exploration of Immunology
The infection of COVID-19 is directly linked to the destruction of lung epithelial cells, and the cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes (cGAS-STING) system has been implicated in the pathology of respiratory infections. This study aimed to systematize the relationship between the pathophysiology of COVID-19 and the cGAS-STING system’s activation in the lungs. Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is an RNA virus that belongs to the Coronaviridae family whose genetic material is produced by a single positive RNA molecule (RNA+). The cGAS-STING signaling pathway has emerged as a key mediator of injury caused by infection and cellular or tissue stress. The cGAS-STING cyclic pathway is part of innate immunity and is activated from cytosolic DNA responses present in newly formed syncytia, by cell-to-cell fusion, in target of angiotensin-converting enzyme 2 (ACE2) expression and SARS-CoV-2 Spike protein. ...
2020
SARS-CoV-2, the virus that has caused the COVID-19 pandemic, robustly activates the host immune system in critically ill patients. Understanding how the virus engages the immune system will facilitate the development of needed therapeutic strategies. Here we demonstrate both in vitro and in vivo that the SARS-CoV-2 surface proteins Spike (S) and Envelope (E) activate the key immune signaling interferon (IFN) pathway in both immune and epithelial cells independent of viral infection and replication. These proteins induce reactive oxidative species generation and increases in human and murine specific IFN-responsive cytokines and chemokines, similar to their upregulation in critically ill COVID-19 patients. Induction of IFN signaling is dependent on canonical but discrepant inflammatory signaling mediators as the activation induced by S is dependent on IRF3, TBK1, and MYD88 while that of E is largely MYD88 independent. Furthermore, these viral surface proteins, specifically E, induced...
Type-I interferon signatures in SARS-CoV-2 infected Huh7 cells
Cell Death Discovery, 2021
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes Coronavirus disease 2019 (COVID-19) has caused a global health emergency. A key feature of COVID-19 is dysregulated interferon-response. Type-I interferon (IFN-I) is one of the earliest antiviral innate immune responses following viral infection and plays a significant role in the pathogenesis of SARS-CoV-2. In this study, using a proteomics-based approach, we identified that SARS-CoV-2 infection induces delayed and dysregulated IFN-I signaling in Huh7 cells. We demonstrate that SARS-CoV-2 is able to inhibit RIG-I mediated IFN-β production. Our results also confirm the recent findings that IFN-I pretreatment is able to reduce the susceptibility of Huh7 cells to SARS-CoV-2, but not post-treatment. Moreover, senescent Huh7 cells, in spite of showing accentuated IFN-I response were more susceptible to SARS-CoV-2 infection, and the virus effectively inhibited IFIT1 in these cells. Finally, proteomic comparison betw...