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1.
PLoS Pathog ; 17(8): e1009800, 2021 08.
Article in English | MEDLINE | ID: covidwho-1435629

ABSTRACT

Type I Interferons (IFN-Is) are a family of cytokines which play a major role in inhibiting viral infection. Resultantly, many viruses have evolved mechanisms in which to evade the IFN-I response. Here we tested the impact of expression of 27 different SARS-CoV-2 genes in relation to their effect on IFN production and activity using three independent experimental methods. We identified six gene products; NSP6, ORF6, ORF7b, NSP1, NSP5 and NSP15, which strongly (>10-fold) blocked MAVS-induced (but not TRIF-induced) IFNß production. Expression of the first three of these SARS-CoV-2 genes specifically blocked MAVS-induced IFNß-promoter activity, whereas all six genes induced a collapse in IFNß mRNA levels, corresponding with suppressed IFNß protein secretion. Five of these six genes furthermore suppressed MAVS-induced activation of IFNλs, however with no effect on IFNα or IFNγ production. In sharp contrast, SARS-CoV-2 infected cells remained extremely sensitive to anti-viral activity exerted by added IFN-Is. None of the SARS-CoV-2 genes were able to block IFN-I signaling, as demonstrated by robust activation of Interferon Stimulated Genes (ISGs) by added interferon. This, despite the reduced levels of STAT1 and phospho-STAT1, was likely caused by broad translation inhibition mediated by NSP1. Finally, we found that a truncated ORF7b variant that has arisen from a mutant SARS-CoV-2 strain harboring a 382-nucleotide deletion associating with mild disease (Δ382 strain identified in Singapore & Taiwan in 2020) lost its ability to suppress type I and type III IFN production. In summary, our findings support a multi-gene process in which SARS-CoV-2 blocks IFN-production, with ORF7b as a major player, presumably facilitating evasion of host detection during early infection. However, SARS-CoV-2 fails to suppress IFN-I signaling thus providing an opportunity to exploit IFN-Is as potential therapeutic antiviral drugs.


Subject(s)
Interferon-beta/metabolism , SARS-CoV-2/immunology , Viral Proteins/metabolism , Adaptor Proteins, Signal Transducing/metabolism , Adaptor Proteins, Vesicular Transport/metabolism , Animals , Chlorocebus aethiops , Eukaryotic Initiation Factor-2/metabolism , HEK293 Cells , Humans , Interferon-beta/genetics , Interferon-beta/pharmacology , SARS-CoV-2/drug effects , STAT1 Transcription Factor/metabolism , Vero Cells , Viral Proteins/genetics
2.
Nat Commun ; 12(1): 4584, 2021 07 28.
Article in English | MEDLINE | ID: covidwho-1387354

ABSTRACT

Interferon-induced transmembrane proteins (IFITMs 1, 2 and 3) can restrict viral pathogens, but pro- and anti-viral activities have been reported for coronaviruses. Here, we show that artificial overexpression of IFITMs blocks SARS-CoV-2 infection. However, endogenous IFITM expression supports efficient infection of SARS-CoV-2 in human lung cells. Our results indicate that the SARS-CoV-2 Spike protein interacts with IFITMs and hijacks them for efficient viral infection. IFITM proteins were expressed and further induced by interferons in human lung, gut, heart and brain cells. IFITM-derived peptides and targeting antibodies inhibit SARS-CoV-2 entry and replication in human lung cells, cardiomyocytes and gut organoids. Our results show that IFITM proteins are cofactors for efficient SARS-CoV-2 infection of human cell types representing in vivo targets for viral transmission, dissemination and pathogenesis and are potential targets for therapeutic approaches.


Subject(s)
Angiotensin-Converting Enzyme 2/genetics , Antigens, Differentiation/genetics , Membrane Proteins/genetics , RNA-Binding Proteins/genetics , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics , Amino Acid Sequence , Angiotensin-Converting Enzyme 2/antagonists & inhibitors , Angiotensin-Converting Enzyme 2/metabolism , Antibodies, Neutralizing/pharmacology , Antigens, Differentiation/metabolism , Binding Sites , COVID-19/virology , Gene Expression Regulation , Host-Pathogen Interactions/drug effects , Host-Pathogen Interactions/genetics , Humans , Interferon-beta/pharmacology , Membrane Proteins/antagonists & inhibitors , Membrane Proteins/metabolism , Protein Binding , Protein Interaction Domains and Motifs , RNA, Small Interfering/genetics , RNA, Small Interfering/metabolism , RNA-Binding Proteins/antagonists & inhibitors , RNA-Binding Proteins/metabolism , SARS-CoV-2/drug effects , SARS-CoV-2/metabolism , Sequence Alignment , Sequence Homology, Amino Acid , Spike Glycoprotein, Coronavirus/metabolism , Virus Attachment/drug effects
3.
Signal Transduct Target Ther ; 6(1): 189, 2021 05 12.
Article in English | MEDLINE | ID: covidwho-1226420

ABSTRACT

Since the outbreak of coronavirus disease 2019 (COVID-19), it has become a global pandemic. The spike (S) protein of etiologic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) specifically recognizes human angiotensin-converting enzyme 2 (hACE2) as its receptor, which is recently identified as an interferon (IFN)-stimulated gene. Here, we find that hACE2 exists on the surface of exosomes released by different cell types, and the expression of exosomal hACE2 is increased by IFNα/ß treatment. In particular, exosomal hACE2 can specifically block the cell entry of SARS-CoV-2, subsequently inhibit the replication of SARS-CoV-2 in vitro and ex vivo. Our findings have indicated that IFN is able to upregulate a viral receptor on the exosomes which competitively block the virus entry, exhibiting a potential antiviral strategy.


Subject(s)
Angiotensin-Converting Enzyme 2/metabolism , Exosomes/metabolism , Interferon-alpha/pharmacology , Interferon-beta/pharmacology , SARS-CoV-2/physiology , Virus Internalization/drug effects , Virus Replication/drug effects , Angiotensin-Converting Enzyme 2/genetics , Animals , Chlorocebus aethiops , Exosomes/genetics , Exosomes/virology , HEK293 Cells , Humans , Mice , Mice, Transgenic , Vero Cells
4.
Cell Res ; 30(12): 1078-1087, 2020 12.
Article in English | MEDLINE | ID: covidwho-912896

ABSTRACT

Silent hypoxia has emerged as a unique feature of coronavirus disease 2019 (COVID-19). In this study, we show that mucins are accumulated in the bronchoalveolar lavage fluid (BALF) of COVID-19 patients and are upregulated in the lungs of severe respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected mice and macaques. We find that induction of either interferon (IFN)-ß or IFN-γ upon SARS-CoV-2 infection results in activation of aryl hydrocarbon receptor (AhR) signaling through an IDO-Kyn-dependent pathway, leading to transcriptional upregulation of the expression of mucins, both the secreted and membrane-bound, in alveolar epithelial cells. Consequently, accumulated alveolar mucus affects the blood-gas barrier, thus inducing hypoxia and diminishing lung capacity, which can be reversed by blocking AhR activity. These findings potentially explain the silent hypoxia formation in COVID-19 patients, and suggest a possible intervention strategy by targeting the AhR pathway.


Subject(s)
Interferons/metabolism , Mucus/metabolism , Receptors, Aryl Hydrocarbon/metabolism , Animals , COVID-19/pathology , COVID-19/virology , Cell Line , Epithelial Cells/cytology , Epithelial Cells/metabolism , Epithelial Cells/virology , Humans , Hypoxia , Interferon-beta/pharmacology , Interferon-gamma/pharmacology , Lung/metabolism , Lung/pathology , Macaca , Mice , Mice, Inbred ICR , Mice, Transgenic , Mucins/metabolism , SARS-CoV-2/isolation & purification , SARS-CoV-2/pathogenicity , Signal Transduction , Up-Regulation/drug effects
5.
Nat Commun ; 11(1): 3810, 2020 07 30.
Article in English | MEDLINE | ID: covidwho-690732

ABSTRACT

The pandemic of COVID-19 has posed an unprecedented threat to global public health. However, the interplay between the viral pathogen of COVID-19, SARS-CoV-2, and host innate immunity is poorly understood. Here we show that SARS-CoV-2 induces overt but delayed type-I interferon (IFN) responses. By screening 23 viral proteins, we find that SARS-CoV-2 NSP1, NSP3, NSP12, NSP13, NSP14, ORF3, ORF6 and M protein inhibit Sendai virus-induced IFN-ß promoter activation, whereas NSP2 and S protein exert opposite effects. Further analyses suggest that ORF6 inhibits both type I IFN production and downstream signaling, and that the C-terminus region of ORF6 is critical for its antagonistic effect. Finally, we find that IFN-ß treatment effectively blocks SARS-CoV-2 replication. In summary, our study shows that SARS-CoV-2 perturbs host innate immune response via both its structural and nonstructural proteins, and thus provides insights into the pathogenesis of SARS-CoV-2.


Subject(s)
Betacoronavirus/physiology , Coronavirus Infections/virology , Immune Evasion , Interferon Type I/metabolism , Pneumonia, Viral/virology , Signal Transduction , Betacoronavirus/genetics , Betacoronavirus/immunology , Betacoronavirus/metabolism , COVID-19 , Cell Line , Coronavirus Infections/immunology , Humans , Immunity, Innate , Interferon-beta/genetics , Interferon-beta/metabolism , Interferon-beta/pharmacology , Mutation , Open Reading Frames , Pandemics , Pneumonia, Viral/immunology , Promoter Regions, Genetic , SARS-CoV-2 , Signal Transduction/drug effects , Viral Proteins/genetics , Viral Proteins/metabolism , Virus Replication/drug effects
6.
J Infect ; 81(4): e1-e10, 2020 10.
Article in English | MEDLINE | ID: covidwho-665494

ABSTRACT

OBJECTIVES: Respiratory and intestinal tract are two primary target organs of SARS-CoV-2 infection. However, detailed characterization of the host-virus interplay in infected human lung and intestinal epithelial cells is lacking. METHODS: We utilized immunofluorescence assays, flow cytometry, and RT-qPCR to delineate the virological features and the innate immune response of the host cells against SARS-CoV-2 infection in two prototype human cell lines representing the human lung (Calu3) and intestinal (Caco2) epithelium when compared with SARS-CoV. RESULTS: Lung epithelial cells were significantly more susceptible to SARS-CoV-2 compared to SARS-CoV. However, SARS-CoV-2 infection induced an attenuated pro-inflammatory cytokines/chemokines induction and type I and type II IFN responses. A single dose of 10 U/mL interferon-ß (IFNß) pretreatment potently protected both Calu3 and Caco2 against SARS-CoV-2 infection. Interestingly, SARS-CoV-2 was more sensitive to the pretreatment with IFNß and IFN inducer than SARS-CoV in Calu3. CONCLUSIONS: Despite robust infection in both human lung and intestinal epithelial cells, SARS-CoV-2 could attenuate the virus-induced pro-inflammatory response and IFN response. Pre-activation of the type I IFN signaling pathway primed a highly efficient antiviral response in the host against SARS-CoV-2 infection, which could serve as a potential therapeutic and prophylactic maneuver to COVID-19 patients.


Subject(s)
Coronavirus Infections/immunology , Interferon Inducers/pharmacology , Interferon-beta/pharmacology , Intestinal Mucosa/immunology , Pneumonia, Viral/immunology , Respiratory Mucosa/immunology , Severe Acute Respiratory Syndrome/immunology , Antiviral Agents/pharmacology , Betacoronavirus/immunology , COVID-19 , Caco-2 Cells , Cell Line, Tumor , Coronavirus Infections/drug therapy , Epithelial Cells/virology , Humans , Immunity, Innate , Lung/immunology , Pandemics , SARS Virus/immunology , SARS-CoV-2
8.
Science ; 369(6504): 712-717, 2020 08 07.
Article in English | MEDLINE | ID: covidwho-594812

ABSTRACT

Excessive cytokine signaling frequently exacerbates lung tissue damage during respiratory viral infection. Type I (IFN-α and IFN-ß) and III (IFN-λ) interferons are host-produced antiviral cytokines. Prolonged IFN-α and IFN-ß responses can lead to harmful proinflammatory effects, whereas IFN-λ mainly signals in epithelia, thereby inducing localized antiviral immunity. In this work, we show that IFN signaling interferes with lung repair during influenza recovery in mice, with IFN-λ driving these effects most potently. IFN-induced protein p53 directly reduces epithelial proliferation and differentiation, which increases disease severity and susceptibility to bacterial superinfections. Thus, excessive or prolonged IFN production aggravates viral infection by impairing lung epithelial regeneration. Timing and duration are therefore critical parameters of endogenous IFN action and should be considered carefully for IFN therapeutic strategies against viral infections such as influenza and coronavirus disease 2019 (COVID-19).


Subject(s)
Alveolar Epithelial Cells/pathology , Cytokines/metabolism , Interferon Type I/metabolism , Interferons/metabolism , Lung/pathology , Orthomyxoviridae Infections/immunology , Orthomyxoviridae Infections/pathology , Alveolar Epithelial Cells/immunology , Animals , Apoptosis , Bronchoalveolar Lavage Fluid/immunology , Cell Differentiation , Cell Proliferation , Cells, Cultured , Cytokines/administration & dosage , Cytokines/immunology , Female , Influenza A Virus, H3N2 Subtype , Interferon Type I/administration & dosage , Interferon Type I/pharmacology , Interferon-alpha/administration & dosage , Interferon-alpha/metabolism , Interferon-alpha/pharmacology , Interferon-beta/administration & dosage , Interferon-beta/metabolism , Interferon-beta/pharmacology , Interferons/administration & dosage , Interferons/pharmacology , Male , Mice , Orthomyxoviridae Infections/metabolism , Receptor, Interferon alpha-beta/genetics , Receptor, Interferon alpha-beta/metabolism , Receptors, Interferon/genetics , Receptors, Interferon/metabolism , Signal Transduction , Tumor Suppressor Protein p53/metabolism
9.
Antiviral Res ; 179: 104811, 2020 07.
Article in English | MEDLINE | ID: covidwho-133419

ABSTRACT

There is an urgent need to identify antivirals to curtail the COVID-19 pandemic. Herein, we report the sensitivity of SARS-CoV-2 to recombinant human interferons α and ß (IFNα/ß). Treatment with IFN-α or IFN-ß at a concentration of 50 international units (IU) per milliliter reduces viral titers by 3.4 log or over 4 log, respectively, in Vero cells. The EC50 of IFN-α and IFN-ß treatment is 1.35 IU/ml and 0.76 IU/ml, respectively, in Vero cells. These results suggest that SARS-CoV-2 is more sensitive than many other human pathogenic viruses, including SARS-CoV. Overall, our results demonstrate the potential efficacy of human Type I IFN in suppressing SARS-CoV-2 infection, a finding which could inform future treatment options for COVID-19.


Subject(s)
Antiviral Agents/pharmacology , Betacoronavirus/drug effects , Coronavirus Infections/drug therapy , Interferon Type I/pharmacology , Pneumonia, Viral/drug therapy , Severe Acute Respiratory Syndrome/drug therapy , Animals , COVID-19 , Chlorocebus aethiops , Coronavirus Infections/immunology , Coronavirus Infections/virology , Humans , Immunity, Innate , Interferon-alpha/pharmacology , Interferon-beta/pharmacology , Pandemics , Pneumonia, Viral/immunology , Pneumonia, Viral/virology , Recombinant Proteins/pharmacology , SARS-CoV-2 , Severe Acute Respiratory Syndrome/immunology , Severe Acute Respiratory Syndrome/virology , Vero Cells , Viral Load/drug effects , Virus Replication/drug effects
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