Presence and short‐term persistence of SARS‐CoV ‐2 neutralizing antibodies in COVID ‐19 convalescent plasma donors

  1. Kyle Annen
  2. Thomas E. Morrison
  3. Melkon G. DomBourian
  4. Mary K. McCarthy
  5. Leah Huey
  6. Patricia A. Merkel
  7. Gillian Andersen
  8. Eileen Schwartz
  9. Vijaya Knight

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Abstract

Background

In March 2020, the Food and Drug Administration (FDA) approved use of COVID‐19 convalescent plasma (CCP) as an investigational new drug for treatment of COVID‐19. Since then, collection of CCP from COVID‐19–recovered patients has been implemented in donor centers nationwide. Childrenʼs Hospital Colorado rapidly put into practice a CCP collection protocol, necessitating development and implementation of assays to evaluate SARS‐CoV‐2 antibodies in CCP units.

Study Design and Methods

We evaluated 87 units of CCP collected from 36 donors over two to four sequential donations using both antigen‐binding assays for SARS‐CoV‐2 nucleoprotein and spike antigens and a live virus focus reduction neutralization test (FRNT 50 ).

Results

Our data show that the majority of donors (83%) had a FRNT 50 titer of at least 80, and 61% had a titer of at least 160, which met the FDAʼs criteria for acceptable CCP units. Additionally, our data indicate that analysis of antibodies to a single SARS‐CoV‐2 antigen is likely to miss a percentage of seroconverters; however, these individuals tend to have neutralizing antibody titers of less than 80. There was considerable variability in the short‐term, sustained antibody response, measured by neutralizing antibody titers, among our donor population.

Conclusion

The correlation of neutralizing activity and antigen‐binding assays is necessary to qualify CCP for therapeutic use. Since SARS‐CoV‐2 antibody levels decline in a percentage of donors, and such a decline is not detectable by current qualitative assays implemented in many laboratories, robust, quantitative assays are necessary to evaluate CCP units best suited for therapeutic infusion in COVID‐19 patients.

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  1. ScreenIT

    SciScore for 10.1101/2020.09.01.20185942: (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
    Plates were washed five times using the kit-specific wash buffer and anti-human IgG horse radish peroxidase (HRP)-conjugated detection antibody was added, followed by a 30 min incubation.
    anti-human IgG
    suggested: None
    Anti-human IgG- HRP conjugated detection antibody was added and plates were incubated for 30 min at 37°C followed by three washes.
    Anti-human IgG-
    suggested: (GenWay Biotech Inc. Cat# 20-783-75007-0.2 mg, RRID:AB_1023061)
    Cells were fixed with 4% paraformaldehyde (Acros Organics, Pittsburgh, PA, USA) and probed with 1 μg/mL of an anti-SARS-CoV spike monoclonal antibody (CR3022, Absolute Antibody, Boston, MA, USA) in Perm Wash (1X PBS/0.1% saponin/0.1% bovine serum albumin [BSA]) for 2 h at RT.
    anti-SARS-CoV
    suggested: None
    CR3022
    suggested: (Imported from the IEDB Cat# CR3022, RRID:AB_2848080)
    Experimental Models: Cell Lines
    SentencesResources
    Focus Reduction Neutralization Assay (FRNT): Vero E6 cells (ATCC, Manassas, VA) were seeded in 96-well plates.
    Vero E6
    suggested: None
    Software and Algorithms
    SentencesResources
    The FRNT50 titer was calculated relative to a virus only control (no serum) set at 100%, using GraphPad Prism 8 (La Jolla, CA, USA) default nonlinear curve fit constrained between 0 and 100%.
    GraphPad Prism
    suggested: (GraphPad Prism, RRID:SCR_002798)
    Data analysis: Data were analyzed using GraphPad Prism Version 8 (San Diego, CA) and Microsoft Excel 2016 (Microsoft, Redmond, WA).
    Microsoft Excel
    suggested: (Microsoft Excel, RRID:SCR_016137)
    For OD450 values and S1-RBD ratios, the mean and 95% confidence intervals were calculated using GraphPad Prism’s statistical analysis package.
    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.

  2. Version published to 10.1111/trf.16261
  3. Version published to 10.1101/2020.09.01.20185942v1 on medRxiv