Imperfect innate immune antagonism renders SARS-CoV-2 vulnerable towards IFN-γ and -λ

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Abstract

The innate immune system constitutes a powerful barrier against viral infections. However, it may fail because successful emerging pathogens, like SARS-CoV-2, evolved strategies to counteract it. Here, we systematically assessed the impact of 29 SARS-CoV-2 proteins on viral sensing, type I, II and III interferon (IFN) signaling, autophagy and inflammasome formation. Mechanistic analyses show that autophagy and type I IFN responses are effectively counteracted at different levels. For example, Nsp14 induces loss of the IFN receptor, whereas ORF3a disturbs autophagy at the Golgi/endosome interface. Comparative analyses revealed that antagonism of type I IFN and autophagy is largely conserved, except that SARS-CoV-1 Nsp15 is more potent in counteracting type I IFN than its SARS-CoV-2 ortholog. Altogether, however, SARS-CoV-2 counteracts type I IFN responses and autophagy much more efficiently than type II and III IFN signaling. Consequently, the virus is relatively resistant against exogenous IFN-α/β and autophagy modulation but remains highly vulnerable towards IFN-γ and -λ treatment. In combination, IFN-γ and -λ act synergistically, and drastically reduce SARS-CoV-2 replication at exceedingly low doses. Our results identify ineffective type I and II antagonism as weakness of SARS-CoV-2 that may allow to devise safe and effective anti-viral therapies based on targeted innate immune activation.

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  1. SciScore for 10.1101/2020.10.15.340612: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Proteins were stained using primary antibodies against β-actin (1:10,000, AC-15, Sigma), strep II-tag (1:1,000, NBP2-43735, Novus), strep II-tag (1:2,000, ab76949, abcam), GAPDH (1:1,000, 607902, Biolegend), pSTAT1 (1:1,000, Y701, Cell Signaling Technology), STAT1 (1:1,000, 9172S, Cell Signaling Technology), pSTAT2 (1:1,000, Y690, Cell Signaling Technology), STAT2 (1:1,000, 4594S, Cell Signaling Technology), IFNAR1 (1:1,000, ab45172, abcam), p62 (1:1,000, GP62-N, ProGen), LC3a/β (1:200
    β-actin
    suggested: (Sigma-Aldrich Cat# A5441, RRID:AB_476744)
    GAPDH
    suggested: (BioLegend Cat# 607902, RRID:AB_2734503)
    pSTAT1
    suggested: (Fluidigm Cat# 3153003, RRID:AB_2661824)
    Y701 , Cell Signaling Technology) , STAT1
    suggested: None
    9172S , Cell Signaling Technology) , pSTAT2 ( 1:1,000 , Y690 , Cell Signaling Technology) , STAT2
    suggested: None
    IFNAR1
    suggested: (Abcam Cat# ab45172, RRID:AB_775764)
    p62
    suggested: (Progen Cat# GP62-N, RRID:AB_2801426)
    GP62-N
    suggested: (Progen Cat# GP62-N, RRID:AB_2801426)
    LC3a/β
    suggested: None
    , M2, Sigma), V5-tag (1:1,000, D3H8Q, Cell Signaling Technology), SARS-CoV-2 (COVID-19) spike antibody (1:1000, 1A9, Biozol), SARS-CoV/SARS-CoV-2
    V5-tag
    suggested: (Cell Signaling Technology Cat# 13202, RRID:AB_2687461)
    The cells were stained using primary antibodies against strep II-tag (1:200, NBP2-43735, Novus) and TGN46 (1:400, AHP500GT, Bio Rad), secondary antibodies fluorescently labelled with AlexaFluor568 targeting rabbit-IgGs (1:400, A10042, Invitrogen) and AlexaFluor647 targeting sheep-IgG (1:400, A21448, Invitrogen), and DAPI (1:1,000) to stain nuclei.
    NBP2-43735
    suggested: None
    TGN46
    suggested: (Bio-Rad Cat# AHP500GT, RRID:AB_2203291)
    A10042
    suggested: (Thermo Fisher Scientific Cat# A10042, RRID:AB_2534017)
    AlexaFluor647 targeting sheep-IgG
    suggested: None
    A21448
    suggested: None
    Experimental Models: Cell Lines
    SentencesResources
    Cell lines and cell culture and viruses: HEK293T cells were purchased from American type culture collection (ATCC: #CRL3216).
    HEK293T
    suggested: ATCC Cat# CRL-3216, RRID:CVCL_0063)
    Generation of stable THP-1 cells: THP-1 cell liens were generated by transduction with lentivirus generated with the indicated pLVX-EF1alpha vectors (kind gift from Nevan Krogan), as well as packaging vectors psPax2 and pMD2.
    THP-1
    suggested: CLS Cat# 300356/p804_THP-1, RRID:CVCL_0006)
    Immunofluorescence: HeLa GL cells were transfected using TransIT-LT1 and grown on coverslips in 24-well plates.
    HeLa GL
    suggested: None
    Inhibition of SARS-CoV-2 by immune modulation: 300,000 Calu-3 cells were seeded in 12-well plates.
    Calu-3
    suggested: None
    The viruses were propagated by infecting 70% confluent Vero E6 in 75 cm2 cell culture flasks at a MOI of 0.003 in 3.5 ml serum-free medium containing 1 μg/ml trypsin.
    Vero E6
    suggested: None
    Proteome analysis: For the proteome analysis of infected cells, 0.6×106 Caco-2 cells were infected with SARS-CoV-2 BetaCoV/Netherlands/01/NL/2020 at an MOI of 0.5 and harvested 24 h and 48 h post infection with TM lysis buffer supplemented with 1:500 protease inhibitor.
    Caco-2
    suggested: None
    Software and Algorithms
    SentencesResources
    Images were acquired using a Zeiss LSM710 and analyzed with Fiji ImageJ.
    Fiji
    suggested: (Fiji, RRID:SCR_002285)
    ImageJ
    suggested: (ImageJ, RRID:SCR_003070)
    The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium via the PRIDE partner repository with the dataset identifier PXD021899.
    PRIDE
    suggested: (Pride-asap, RRID:SCR_012052)
    MaxQuant 1.6.15.0 was used to identify proteins and quantify by LFQ with the following parameters: Database, Uniprot_AUP000005640_Hsapiens_20200120.fasta supplemented with the sequences of NSP1_V5, NSP7_V5, NSP15_V5, NSP16_V5, E_V5, M_V5, N_V5, S_V5, ORF3_V5, ORF6_V5, ORF7_V5 and Spike protein from SARSCoV239; MS tol, 10ppm; MS/MS tol, 20ppm
    MaxQuant
    suggested: (MaxQuant, RRID:SCR_014485)
    GO Analysis: From the proteome of the respective samples, proteins regulated more than 4-fold compared to the vector control were extracted and submitted to PANTHER (cellular component analysis).
    PANTHER
    suggested: (PANTHER, RRID:SCR_004869)
    We used MATLAB 2019b for the half-life analysis.
    MATLAB
    suggested: (MATLAB, RRID:SCR_001622)
    Statistical analysis: Statistical analyses were performed using GraphPad PRISM 8 (GraphPad Software).
    GraphPad PRISM
    suggested: (GraphPad Prism, RRID:SCR_002798)
    GraphPad
    suggested: (GraphPad Prism, RRID:SCR_002798)

    Results from OddPub: Thank you for sharing your data.


    Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    Results from TrialIdentifier: No clinical trial numbers were referenced.


    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.


    Results from JetFighter: We did not find any issues relating to colormaps.


    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

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