Four doses of the inactivated SARS-CoV-2 vaccine redistribute humoral immune responses away from the Receptor Binding Domain

  1. Ji Wang
  2. Caiguangxi Deng
  3. Ming Liu
  4. Yihao Liu
  5. Liubing Li
  6. Zhangping Huang
  7. Liru Shang
  8. Juan Jiang
  9. Yongyong Li
  10. Ruohui Mo
  11. Hui Zhang
  12. Min Liu
  13. Sui Peng
  14. Haipeng Xiao

Reviewed by

Read the full article See related articles

Listed in

Log in to save this article

Abstract

A recent MMWR reported that the effectiveness of a 3 rd dose of SARS-CoV-2 mRNA vaccine waned quickly in the Omicron-predominant period. Similarly, a substantial decline of immune responses induced by a 3 rd dose of inactivated vaccines was also observed in our study. In response to the fast waning immune response and the great threat of Omicron variant of concern (VOC) to frontline healthcare workers (HCWs), 38 HCWs who were in our previous cohort investigating responses to the first three doses of inactivated vaccines participated in the current study and volunteered to receive a 4 th homologous booster. Here, we demonstrated that the 4 th dose is safe and capable of recalling waned immune responses 6 months after the 3 rd dose. However, a greater suppression on the induction of overall Neutralizing antibodies (NAbs) and NAbs targeting the receptor-binding domain (RBD) was found in participants with stronger immune responses after the 3 rd dose. As a result, a stepwise elevation of RBD-NAbs from the 1 st to the 3 rd vaccination achieved a “turning point”. The peak RBD-NAbs level induced by the 4 th dose was inferior to the peak of the 3 rd dose. Accompanied with reduced induction of RBD-NAbs, the immune system shifted responses to the nucleocapsid protein (NP) and the N-terminal domain (NTD) of the spike protein. Although NTD directed antibodies are capable of neutralization, they only compensated the loss of RBD-NAbs to ancestral SARS-CoV-2 virus but not to the Omicron variant due to a substantial conformational change of Omicron NTD. This longitudinal clinical study monitored the immune response of the same cohort for every doses, shaping a relationship between the trajectory of immune focus and the dynamics of the neutralizing potency against the evolving virus. Our data reveal that immune responses could not be endlessly elevated, while suppression of heightened immune responses focusing on one subunit together with a shift of immune responses to other subunits would occur after repeated vaccination. Thus, an updated vaccine with more diverse epitopes capable of inducing NAbs against VOCs would be a future direction for boosters.

Article activity feed

  1. ScreenIT

    SciScore for 10.1101/2022.02.19.22271215: (What is this?)

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

    Table 1: Rigor

    EthicsIRB: All studies were approved by the Institutional Review Board of FAH-SYSU and written consent was obtained from all participants.
    Consent: All studies were approved by the Institutional Review Board of FAH-SYSU and written consent was obtained from all participants.
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Cell Line AuthenticationContamination: All cell lines were passaged less than 15 generations and examined the mycoplasma by PCR and fluorescence labeling methods.

    Table 2: Resources

    Antibodies
    SentencesResources
    Plates were washed 5 times by PBST, and incubated with 100 μl/well goat HRP conjugated anti-human IgG antibody (2040-05, SouthernBiotech, 1:3000) in PBST at room temperature for 30 min.
    anti-human IgG
    suggested: (SouthernBiotech Cat# 2040-05, RRID:AB_2795644)
    Experimental Models: Cell Lines
    SentencesResources
    Jurkat-Lucia™ NFAT-CD16 Cells (jktl-nfat-cd16, InvivoGen) was cultured in IMDM (BL312A, Biosharp) supplemented with 10% FBS, NEAA, 100 U/ml penicillin and 100 μg/ml streptomycin, 100 μg/ml Zeocin (ST-1450, Beyotime) and 10
    NFAT-CD16
    suggested: RRID:CVCL_A7ZT)
    For the generation of the B.1.1.529 Omicron-variant spike pseudovirus, pcDNA3.1(+)-Omicron-spike, pSPAX2 and pLenti-CMV-puro-Luc (168w-1) were co-transfected to HEK293T using Lipo8000.
    HEK293T
    suggested: None
    Recombinant DNA
    SentencesResources
    The plasmid pcDNA3.1-2019-nCoV-Spike is a gift from Dr. Lu Lu at Fudan University, encoding the spike protein from an ancestral SARS-CoV-2 reference strain (Wuhan-Hu-1) which is called as wild type (WT) throughout the manuscript.
    pcDNA3.1-2019-nCoV-Spike
    suggested: None
    The plasmid pcDNA3.1(+)-Envelope encodes envelope protein from WT was full-genome synthesized by Genewiz China according to the reference sequence NC_045512.2 in NCBI.
    pcDNA3.1
    suggested: RRID:Addgene_79663)
    Plasmids pSPAX2 and pLenti-CMV-Puro-Luc (168w-1) were a gift from Dr. Jianping Guo and purchased from MiaolingBio (P1216), respectively.
    pSPAX2
    suggested: RRID:Addgene_12260)
    To generate WT SARS-CoV-2-Spike (Wuhan-Hu-1) pseudovirus, pcDNA3.1-2019-nCoV-Spike, pSPAX2 and pLenti-CMV-puro-Luc (168w-1) were co-transfected to HEK293T using Lipo8000 (C0533, Beyotime) according to the manufacturer’s instruction.
    pLenti-CMV-puro-Luc
    suggested: None
    Software and Algorithms
    SentencesResources
    The 50% pseudovirus neutralization titer (PVNT50) was determined by a four-parameter nonlinear regression curve (GraphPad Prism).
    GraphPad
    suggested: (GraphPad Prism, RRID:SCR_002798)
    Statistical analysis: Statistical analysis was performed using Graphpad Prism.
    Graphpad Prism
    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: We detected the following sentences addressing limitations in the study:
    Our study has several limitations. First, the result came from a cohort of young HCWs. The effect of the 4th dose on very young and elderly populations may be different. Second, only a pseudovirus neutralization assay was used in the current study 13. Nevertheless, our neutralization results regarding the ratio of NAb titers between WT and Omicron are in line with results from pseudovirus neutralization assay or authentic virus neutralization assay from other groups 8,16,20. Third, we did not assess other aspects of humoral immune responses such as antibody-dependent cellular cytotoxicity (ADCC) or the cellular arm of immunity. They may contribute to disease prevention even in the absence of NAbs. In conclusion, our study demonstrated that the 4th dose of inactivated SARS-CoV-2 vaccine is safe but the ability to further strengthen the protection against Omicron is compromised by suppression of RBD-NAbs and a further shift of humoral response away from RBD. Updated vaccines based on VOC sequences that take the advantage of RBD, NTD, and other antigenic domains would be an ideal alternative for future boosters.

    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.

  2. Version published to 10.1101/2022.02.19.22271215v1 on medRxiv