Anti-SARS-Cov-2 S-RBD IgG Formed after BNT162b2 Vaccination Can Bind C1q and Activate Complement

  1. Anas H. A. Abu-Humaidan
  2. Fatima M. Ahmad
  3. Dima Awajan
  4. Raba’a F. Jarrar
  5. Nader Alaridah

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Abstract

Background. The ability of vaccine-induced antibodies to bind C1q could affect pathogen neutralization. In this study, we investigated C1q binding and subsequent complement activation by anti-spike (S) protein receptor-binding domain (RBD) specific antibodies produced following vaccination with either the mRNA vaccine BNT162b2 or the inactivated vaccine BBIBP-CorV. Methods. Serum samples were collected in the period of July 2021-March 2022. Participants’ demographic data, type of vaccine, date of vaccination, as well as adverse effects of the vaccine were recorded. The serum samples were incubated with S protein RBD-coated plates. Levels of human IgG, IgA, IgM, C1q, and mannose-binding lectin (MBL) that were bound to the plate, as well as formed C3d, and C5b-9 were compared between different groups of participants. Results. A total of 151 samples were collected from vaccinated ( n = 116 ) and nonvaccinated ( n = 35 ) participants. Participants who received either one or two doses of BNT162b2 formed higher levels of anti-RBD IgG and IgA than participants who received BBIBP-CorV. The anti-RBD IgG formed following either vaccine bound C1q, but significantly more C1q binding was observed in participants who received BNT162b2. Subsequently, C5b-9 formation was significantly higher in participants who received BNT162b2, while no significant difference in C5b-9 formation was found between the nonvaccinated and BBIBP-CorV groups. The formation of C5b-9 was strongly correlated to C1q binding and not to MBL binding, additionally, the ratio of formed C5b-9/bound C1q was significantly higher in the BNT162b2 group. Conclusion. Anti-RBD IgG formed following vaccination can bind C1q with subsequent complement activation, and the degree of terminal complement pathway activation differed between vaccines, which could play a role in the protection offered by COVID-19 vaccines. Further investigation into the correlation between vaccine protection and vaccine-induced antibodies’ ability to activate complement is required.

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  1. Version published to 10.1155/2022/7263740
  2. ScreenIT

    SciScore for 10.1101/2022.04.24.489298: (What is this?)

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

    Table 1: Rigor

    EthicsField Sample Permit: Sample collection: Samples were collected in plain blood collection tubes with a gel separator, then immediately preserved at 4°C and allowed to clot for a maximum of 2 hours.
    IRB: Ethical approval: The study protocol was approved by the Institutional Review Board (IRB) at UJ (Ref. No. 68/2021).
    Consent: A written and signed informed consent was obtained from all participants who agreed to participate following a full explanation of the study objectives.
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    For IgG and IgM measurement, plates were incubated with either horseradish peroxidase (HRP)-conjugated rabbit anti-human IgG polyclonal antibodies (Abcam), or HRP-conjugated rabbit anti-human IgM polyclonal antibodies (Novus) respectively, both at a concentration of 1:2000 in blocking buffer at 4° C overnight.
    anti-human IgG
    suggested: (Abcam Cat# 2000-1, RRID:AB_765103)
    anti-human IgM
    suggested: None
    While for C1q and C5b-9 measurement, the wells were washed three times with PBST, then incubated with either rabbit anti-human C1q polyclonal antibodies (MyBioSource) or mouse anti-human C5b-9 monoclonal antibodies (Novus), respectively, at a concentration of 1:500 in blocking buffer at 4° C overnight.
    anti-human C1q
    suggested: None
    anti-human C5b-9
    suggested: None
    The next day, the wells were washed three times with PBST, then incubated with the following secondary antibodies for 3 hours at room temperature; HRP-conjugated goat anti-rabbit polyclonal antibodies (Novex Life Technologies) for C1q, and HRP-conjugated goat anti-mouse polyclonal antibodies (Abcam) for C5b-9.
    anti-rabbit
    suggested: None
    C1q
    suggested: None
    anti-mouse polyclonal antibodies
    suggested: None
    C5b-9
    suggested: None
    Software and Algorithms
    SentencesResources
    The image files were analyzed using Fiji/ImageJ [16].
    Fiji/ImageJ
    suggested: None
    Data Analysis: Data generated was organized in Microsoft Excel, and statistical analysis was carried out using GraphPad prism 8 software for analysis.
    Microsoft Excel
    suggested: (Microsoft Excel, RRID:SCR_016137)
    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.

    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 10.1101/2022.04.24.489298v1 on bioRxiv