Characteristics of Anti-SARS-CoV-2 Antibodies in Recovered COVID-19 Subjects

  1. Angela Huynh
  2. Donald M. Arnold
  3. James W. Smith
  4. Jane C. Moore
  5. Ali Zhang
  6. Zain Chagla
  7. Bart J. Harvey
  8. Hannah D. Stacey
  9. Jann C. Ang
  10. Rumi Clare
  11. Nikola Ivetic
  12. Vasudhevan T. Chetty
  13. Dawn M. E. Bowdish
  14. Matthew S. Miller
  15. John G. Kelton
  16. Ishac Nazy

Reviewed by

Read the full article See related articles

Listed in

Log in to save this article

Abstract

Coronavirus Disease 2019 (COVID-19) is a global pandemic caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). While detection of SARS-CoV-2 by polymerase chain reaction with reverse transcription (RT-PCR) is currently used to diagnose acute COVID-19 infection, serological assays are needed to study the humoral immune response to SARS-CoV-2. Anti-SARS-CoV-2 immunoglobulin (Ig)G/A/M antibodies against spike (S) protein and its receptor-binding domain (RBD) were characterized in recovered subjects who were RT-PCR-positive (n = 153) and RT-PCR-negative (n = 55) using an enzyme-linked immunosorbent assay (ELISA). These antibodies were also further assessed for their ability to neutralize live SARS-CoV-2 virus. Anti-SARS-CoV-2 antibodies were detected in 90.9% of resolved subjects up to 180 days post-symptom onset. Anti-S protein and anti-RBD IgG titers correlated (r = 0.5157 and r = 0.6010, respectively) with viral neutralization. Of the RT-PCR-positive subjects, 22 (14.3%) did not have anti-SARS-CoV-2 antibodies; and of those, 17 had RT-PCR cycle threshold (Ct) values > 27. These high Ct values raise the possibility that these indeterminate results are from individuals who were not infected or had mild infection that failed to elicit an antibody response. This study highlights the importance of serological surveys to determine population-level immunity based on infection numbers as determined by RT-PCR.

Article activity feed

  1. Version published to 10.3390/v13040697
  2. Version published to 10.1101/2020.09.11.20192690v2 on medRxiv
  3. ScreenIT

    SciScore for 10.1101/2020.09.11.20192690: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board StatementIRB: This study was approved by the Hamilton Integrated Research Ethics Board (HIREB) and informed written consent was obtained from all participants
    Consent: This study was approved by the Hamilton Integrated Research Ethics Board (HIREB) and informed written consent was obtained from all participants
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Bound human antibodies (IgG, IgA, or IgM) were detected with alkaline phosphatase conjugated goat anti-human IgG (γ-chain-specific, 1/2000, Jackson ImmunoResearch Laboratories, Inc, Westgrove, PA, USA)
    anti-human IgG
    suggested: None
    , goat anti-human IgA (α-chain-specific; 1/500, Jackson ImmunoResearch Laboratories, Inc, Westgrove, PA, USA) antibody, or goat anti-human IgM (μ-chain-specific; 1/1000, Jackson ImmunoResearch Laboratories, Inc, Westgrove, PA, USA) antibody prepared in PBS/0.05% Tween 20.
    anti-human IgA
    suggested: (LSBio (LifeSpan Cat# LS-C21944-6, RRID:AB_900131)
    α-chain-specific
    suggested: None
    anti-human IgM
    suggested: None
    Results were reported as an optical density (405 nm with reference 490 nm) for each antigen and antibody isotype (IgG, IgA and IgM).
    antibody isotype (IgG
    suggested: None
    IgM
    suggested: None
    Inhibition of IgG anti-RBD binding: To confirm the specificity of antibodies detected by the ELISA, we inhibited the binding of selected serum samples with excess fluid-phase RBD.
    anti-RBD
    suggested: None
    The same set of COVID-19 positive and pre-COVID-19 controls was also tested by the Hamilton Regional Laboratory Medicine Program (HRLMP) in the Ortho Clinical Diagnostics COVID-19 IgG Antibody Test that measures anti-S protein IgG for comparison.
    anti-S protein IgG
    suggested: None
    Experimental Models: Cell Lines
    SentencesResources
    In brief, proteins were produced in Expi293 cells (ThermoFisher, Waltham, MA, USA) using the manufacturer’s instructions.
    Expi293
    suggested: RRID:CVCL_D615)
    Software and Algorithms
    SentencesResources
    All statistical analyses were conducted using GraphPad Prism (version 7.0a, GraphPad Software, San Diego, USA).
    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

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  4. Version published to 10.1101/2020.09.11.20192690v1 on medRxiv