Persistence of Anti-SARS-CoV-2 Antibodies in Non-Hospitalized COVID-19 Convalescent Health Care Workers

  1. Margherita Bruni
  2. Valentina Cecatiello
  3. Angelica Diaz-Basabe
  4. Georgia Lattanzi
  5. Erika Mileti
  6. Silvia Monzani
  7. Laura Pirovano
  8. Francesca Rizzelli
  9. Clara Visintin
  10. Giuseppina Bonizzi
  11. Marco Giani
  12. Marialuisa Lavitrano
  13. Silvia Faravelli
  14. Federico Forneris
  15. Flavio Caprioli
  16. Pier Giuseppe Pelicci
  17. Gioacchino Natoli
  18. Sebastiano Pasqualato
  19. Marina Mapelli
  20. Federica Facciotti

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Abstract

Although antibody response to SARS-CoV-2 can be detected early during the infection, several outstanding questions remain to be addressed regarding the magnitude and persistence of antibody titer against different viral proteins and their correlation with the strength of the immune response. An ELISA assay has been developed by expressing and purifying the recombinant SARS-CoV-2 Spike Receptor Binding Domain (RBD), Soluble Ectodomain (Spike), and full length Nucleocapsid protein (N). Sera from healthcare workers affected by non-severe COVID-19 were longitudinally collected over four weeks, and compared to sera from patients hospitalized in Intensive Care Units (ICU) and SARS-CoV-2-negative subjects for the presence of IgM, IgG and IgA antibodies as well as soluble pro-inflammatory mediators in the sera. Non-hospitalized subjects showed lower antibody titers and blood pro-inflammatory cytokine profiles as compared to patients in Intensive Care Units (ICU), irrespective of the antibodies tested. Noteworthy, in non-severe COVID-19 infections, antibody titers against RBD and Spike, but not against the N protein, as well as pro-inflammatory cytokines decreased within a month after viral clearance. Thus, rapid decline in antibody titers and in pro-inflammatory cytokines may be a common feature of non-severe SARS-CoV-2 infection, suggesting that antibody-mediated protection against re-infection with SARS-CoV-2 is of short duration. These results suggest caution in using serological testing to estimate the prevalence of SARS-CoV-2 infection in the general population.

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  1. ScreenIT

    SciScore for 10.1101/2020.07.30.20164368: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board StatementIRB: Clearance from the Ethical Committee has been obtained (IEO1271).
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    After binding of the proteins (RBD and N proteins) to a Nunc Maxisorp ELISA plate, And blocking aspecific bindings with PBS-BSA 3%, patients’ sera to be analyzed were applied to the plate to allow antibody binding at a final dilution of 1:200, revealed with secondary anti-human-IgG (BD, clone G18-145), IgM (Merck, Polyclonal code A6907) IgA (Biolegend, Poly24110) antibody conjugated to HRP.
    anti-human-IgG (BD
    suggested: None
    IgA
    suggested: (BioLegend Cat# 411002, RRID:AB_2686938)
    Poly24110
    suggested: (BioLegend Cat# 411002, RRID:AB_2686938)
    Experimental Models: Cell Lines
    SentencesResources
    Antigen proteins production: The recombinant Spike SARS-CoV2 glycoprotein receptor binding domain (RBD) and the soluble full-length trimeric ectodomain have been produced in mammalian HEK293F cells as glycosylated proteins by transient transfection with pCAGGS vectors generated in Prof.
    HEK293F
    suggested: RRID:CVCL_6642)
    Software and Algorithms
    SentencesResources
    Prism software was used for all statistical analyses.
    Prism
    suggested: (PRISM, RRID:SCR_005375)

    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.
    • Thank you for including a protocol registration statement.

    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 10.3390/jcm9103188
  3. Version published to 10.1101/2020.07.30.20164368 on medRxiv