Titers of antibodies the receptor-binding domain (RBD) of ancestral SARS-CoV-2 are predictive for levels of neutralizing antibodies to multiple variants

  1. Trung The Tran
  2. Eline Benno Vaage
  3. Adi Mehta
  4. Adity Chopra
  5. Anette Kolderup
  6. Aina Anthi
  7. Marton König
  8. Gro Nygaard
  9. Andreas Lind
  10. Fredrik Müller
  11. Lise Sofie Nissen-Meyer
  12. Per Magnus
  13. Lill Trogstad
  14. Siri Mjaaland
  15. Arne Søraas
  16. Karsten Midtvedt
  17. Anders Åsberg
  18. Andreas Barratt-Due
  19. Asle W. Medhus
  20. Marte Lie Høivk
  21. Knut Lundin
  22. Randi Fuglaas Karlsen
  23. Reidun Dahle
  24. Karin Danielsson
  25. Kristine Stien Thomassen
  26. Grete Birkeland Kro
  27. Rebecca J. Cox
  28. Fan Zhou
  29. Nina Langeland
  30. Pål Aukrust
  31. Espen Melum
  32. Tone Lise Åvitsland
  33. Kristine Wiencke
  34. Jan Cato Holter
  35. Ludvig A. Munthe
  36. Gunnveig Grødeland
  37. Jan-Terje Andersen
  38. John Torgils Vaage
  39. Fridtjof Lund-Johansen

Reviewed by

Read the full article

Listed in

Log in to save this article

Abstract

Diagnostic assays currently used to monitor the efficacy of COVID-19 vaccines measure levels of antibodies to the receptor-binding domain of ancestral SARS-CoV-2 (RBDwt). However, the predictive value for protection against new variants of concern (VOCs) has not been firmly established. Here, we used bead-based arrays and flow cytometry to measure binding of antibodies to spike proteins and receptor-binding domains (RBDs) from VOCs in 12,000 sera. Effects of sera on RBD-ACE2 interactions were measured as a proxy for neutralizing antibodies. The samples were obtained from healthy individuals or patients on immunosuppressive therapy who had received two to four doses of COVID-19 vaccines and from COVID-19 convalescents. The results show that anti-RBDwt titers correlate with the levels of binding- and neutralizing antibodies against the Alpha, Beta, Gamma, Delta, Epsilon and Omicron variants. The benefit of multiplexed analysis lies in the ability to measure a wide range of anti-RBD titers using a single dilution of serum for each assay. The reactivity patterns also yield an internal reference for neutralizing activity and binding antibody units per milliliter (BAU/ml). Results obtained with sera from vaccinated healthy individuals and patients confirmed and extended results from previous studies on time-dependent waning of antibody levels and effects of immunosuppressive agents. We conclude that anti-RBDwt titers correlate with levels of neutralizing antibodies against VOCs and propose that our method may be implemented to enhance the precision and throughput of immunomonitoring.

Article activity feed

  1. Version published to 10.1101/2022.03.26.484261v2 on bioRxiv
  2. ScreenIT

    SciScore for 10.1101/2022.03.26.484261: (What is this?)

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

    Table 1: Rigor

    EthicsConsent: Serum samples: All participants gave informed consent before taking part in the study.
    IRB: Samples from Bergen were from studies approved by the Northern and Western Norway Regional Ethical Committees (approval numbers 218629, 118664).
    Field Sample Permit: All studies were approved by the Norwegian Regional Ethical Committee (reference numbers: 200631, 127798, 2021/8504, 135924, 204104).
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Experimental Models: Cell Lines
    SentencesResources
    The SARS-CoV-2 virus Human 2019-nCoV strain 2019-nCoV/Italy-InMI1 (008V-03893) from the European Virus Archive (EVA) was detected in Vero E6 cell cultures by ELISA using a mAb against SARS-CoV-2 nucleocapsid (40143-R004, SinoBiological) and HRP-conjugated goat anti-rabbit IgG-Fc mAb (SSA003, SinoBiological).
    Vero E6
    suggested: None
    Mixtures were transferred to 96-well plates seeded with Vero cells.
    Vero
    suggested: CLS Cat# 605372/p622_VERO, RRID:CVCL_0059)
    Recombinant DNA
    SentencesResources
    Expression and hapten-conjugation of recombinant ACE2: cDNA encoding a truncated human ACE2 fused to human albumin was sub-cloned into pFUSE2ss-CLIg-hk (InvivoGen).
    pFUSE2ss-CLIg-hk
    suggested: None
    Software and Algorithms
    SentencesResources
    The secreted fusion protein was purified on a CaptureSelect™ human albumin affinity matrix (Life Technologies), and protein eluted by adding 20 mM Tris and 2.0 M MgCl2, pH 7.0 before up-concentration using Amicon®
    Amicon®
    suggested: None
    Further analysis was performed in Microsoft Excel.
    Microsoft Excel
    suggested: (Microsoft Excel, RRID:SCR_016137)
    To visualize results as colored dot plots, we exported data from Excel to WinList 3D.
    Excel
    suggested: None
    Optical density (OD) was measured at 450/620 nm using the Synergy H1 Hybrid Multi-Mode Reader with the Gen5 2.00 (version 2.00.18) software (BioTek Instruments Inc., Winooski, VT, USA).
    Gen5
    suggested: (Gen5, RRID:SCR_017317)

    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: We detected the following sentences addressing limitations in the study:
    The present study has limitations. First, we only measured serum neutralization of SARS-CoV-2wt. Further studies are needed to determine exact predictive values of Multi-IgG-RBD-ACE2 for protection against each VOC. Second, RBD-ACE2 interaction assays do not measure neutralizing antibodies binding outside of the RBD or factors that promote infectivity, such as virus replication rates. This may explain why the results shown in Fig. 3c did not recapitulate published differences in neutralizing titers for Delta and SARS-CoV-2wt (Fig. 3c) 37,40. The implication is that neutralization assays are still needed to establish if titers for new variants correlate with anti-RBD-wt levels 3. Finally, the arrays used for large-scale analysis of early vaccine responses shown in Fig. 8, did not contain RBD from Omicron. Reanalysis is necessary to determine if Omicron-neutralizing antibodies appear early, or first after many months of affinity maturation as suggested in a recent review 20. The results may have implications for establishing optimal dose intervals. In conclusion, we show that anti-RBDwt titers in post-vaccine sera are broadly predictive for levels of neutralizing antibodies to VOCs. Our results also demonstrate the feasibility and utility of Multi-IgG-ACE2-RBD in large-scale immunomonitoring.

    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.

    Results from scite Reference Check: We found no unreliable references.

    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.

  3. Version published to 10.1101/2022.03.26.484261v1 on bioRxiv