SARS-CoV2 envelop proteins reshape the serological responses of COVID-19 patients

  1. Sophie Martin
  2. Christopher Heslan
  3. Gwénaële Jégou
  4. Leif A. Eriksson
  5. Matthieu Le Gallo
  6. Vincent Thibault
  7. Eric Chevet
  8. Florence Godey
  9. Tony Avril

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Abstract

The SARS-CoV-2 pandemic has elicited a unique international mobilization of the scientific community to better understand this coronavirus and its associated disease and to develop efficient tools to combat infection. Similar to other coronavirae , SARS-CoV-2 hijacks the host cell complex secretory machinery to produce properly folded viral proteins that will compose the nascent virions; including Spike, Envelope and Membrane proteins, the most exposed membrane viral proteins to the host immune system. Antibody response is part of the anti-viral immune arsenal that infected patients develop to fight viral particles in the body. Herein, we investigate the immunogenic potential of Spike (S), Envelope (E) and Membrane (M) proteins using a human cell-based system to mimic membrane insertion and N-glycosylation. We show that both S and M proteins elicit the production of specific IgG, IgM and IgA in SARS-CoV-2 infected patients. Elevated Ig responses were observed in COVID+ patients with moderate and severe forms of the disease. Finally, when SARS-CoV-2 Spike D614 and G614 variants were compared, reduced Ig binding was observed with the Spike G614 variant. Altogether, this study underlines the needs for including topological features in envelop proteins to better characterize the serological status of COVID+ patients, points towards an unexpected immune response against the M protein and shows that our assay could represent a powerful tool to test humoral responses against actively evolving SARS-CoV-2 variants and vaccine effectiveness.

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  1. ScreenIT

    SciScore for 10.1101/2021.02.15.431237: (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
    We also used the rabbit monoclonal anti-SARS-CoV-2 Spike S1 (Sino Biologicals, Clinisciences, Nanterre, France) antibody.
    anti-SARS-CoV-2
    suggested: None
    The membranes were blocked with 3% bovine serum albumin in 0.1% Tween 20 PBS and incubated with rabbit anti-Spike antibody (1 in 1000 dilution) for Spike (D614 and G614 variants) detection; with HRP-conjugated StrepTactin (1 in 10000 dilution) for S, E and M detection; or with anti-FLAG (1 in 10000 dilution) for FLAG-tagged S protein.
    anti-FLAG
    suggested: None
    Anti-Spike antibody binding was detected using HRP-conjugated anti-rabbit secondary antibodies (1 in 7000 dilution) (Dako) and visualized using ECL (KPL, Eurobio, Courtaboeuf, France) according to the manufacturer’s instructions.
    anti-rabbit
    suggested: None
    For Spike expression, cells were incubated with rabbit anti-Spike antibody for 30 minutes at 4°C, washed three times in PBS 2% FBS, and incubated with AF488 conjugated anti-rabbit antibody for 30 minutes at 4°C.
    anti-Spike
    suggested: None
    Cells were washed in PBS FBS/DS and incubated with AF488 and AF647 conjugated donkey anti-human IgG and IgM F(ab’)2 antibodies or AF488 conjugated goat anti-human IgA F(ab’)2 antibodies for 30 minutes at 4°C.
    anti-human IgG
    suggested: None
    IgM F(ab’)2
    suggested: (SouthernBiotech Cat# 1022-30, RRID:AB_2794267)
    anti-human IgA F(ab’)2
    suggested: None
    Experimental Models: Cell Lines
    SentencesResources
    Cell culture and transfection: Human epithelial HEK293T (HEK) cells were grown in Dulbecco’s modified Eagle’s medium (Gibco, Thermo Fisher Scientific) supplemented with 10% heat-inactivated fetal bovine serum (FBS) in a 5% CO2 humidified atmosphere at 37°C.
    HEK293T
    suggested: None
    HEK
    suggested: None
    Software and Algorithms
    SentencesResources
    Molecular modeling: Sequences used for predicted protein structures of Spike D614 variant (PDB ID 6ZB5, EM 2.85Å resolution) and G614 variant (PDB ID 6XS6, EM 3.70Å resolution, lacking the RBD domain) were initially aligned using ClustalOmega.
    ClustalOmega
    suggested: None
    Statistical analyses: Graphs and statistical analyses were performed using GraphPad Prism 7.0 software (GraphPad Software).
    GraphPad Prism
    suggested: (GraphPad Prism, RRID:SCR_002798)
    GraphPad
    suggested: (GraphPad Prism, RRID:SCR_002798)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    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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  2. Version published to 10.1101/2021.02.15.431237v2 on bioRxiv
  3. Version published to 10.1101/2021.02.15.431237v1 on bioRxiv