Single-component, self-assembling, protein nanoparticles presenting the receptor binding domain and stabilized spike as SARS-CoV-2 vaccine candidates

  1. Linling He
  2. Xiaohe Lin
  3. Ying Wang
  4. Ciril Abraham
  5. Cindy Sou
  6. Timothy Ngo
  7. Yi Zhang
  8. Ian A. Wilson
  9. Jiang Zhu

Reviewed by

Read the full article See related articles

Listed in

Log in to save this article

Abstract

Vaccination against SARS-CoV-2 provides an effective tool to combat the COIVD-19 pandemic. Here, we combined antigen optimization and nanoparticle display to develop vaccine candidates for SARS-CoV-2. We first displayed the receptor-binding domain (RBD) on three self-assembling protein nanoparticle (SApNP) platforms using the SpyTag/SpyCatcher system. We then identified heptad repeat 2 (HR2) in S2 as the cause of spike metastability, designed an HR2-deleted glycine-capped spike (S2GΔHR2), and displayed S2GΔHR2 on SApNPs. An antibody column specific for the RBD enabled tag-free vaccine purification. In mice, the 24-meric RBD-ferritin SApNP elicited a more potent neutralizing antibody (NAb) response than the RBD alone and the spike with two stabilizing proline mutations in S2 (S2P). S2GΔHR2 elicited two-fold-higher NAb titers than S2P, while S2GΔHR2 SApNPs derived from multilayered E2p and I3-01v9 60-mers elicited up to 10-fold higher NAb titers. The S2GΔHR2-presenting I3-01v9 SApNP also induced critically needed T-cell immunity, thereby providing a promising vaccine candidate.

ONE-SENTENCE SUMMARY

The SARS-CoV-2 receptor binding domain and S2GΔHR2 spike elicited potent immune responses when displayed on protein nanoparticles as vaccine candidates.

Article activity feed

  1. Version published to 10.1101/2020.09.14.296715v2 on bioRxiv
  2. Version published to 10.1126/sciadv.abf1591
  3. ScreenIT

    SciScore for 10.1101/2020.09.14.296715: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board StatementIACUC: Briefly, the Institutional Animal Care and Use Committee (IACUC) guidelines were followed with animal subjects tested in the immunization study.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    The CR3022 antibody column was used to extract SARS-CoV-1/2 antigens from the supernatants, which was followed by SEC on a Superdex 200 10/300 GL column (for scaffolded RBD trimer) or a Superose 6 10/300 GL column (for RBD-SPY-SApNPs, spikes, and spike-presenting SApNPs).
    CR3022
    suggested: (Imported from the IEDB Cat# CR3022, RRID:AB_2848080)
    For antigen binding, antibodies were diluted in the blocking buffer to a maximum concentration of 5 μg ml−1 followed by a 10-fold dilution series.
    antigen binding ,
    suggested: None
    For antibody binding, a 1:5000 dilution of goat anti-human IgG antibody (Jackson ImmunoResearch Laboratories, Inc), or for mouse sample analysis, a 1:3000 dilution of horseradish peroxidase (HRP)-labeled goat anti-mouse IgG antibody (Jackson ImmunoResearch Laboratories), was then made in the wash buffer (PBS containing 0.05% Tween 20), with 50 μl of this diluted secondary antibody added to each well.
    anti-human IgG
    suggested: None
    anti-mouse IgG
    suggested: None
    For all antigens with the exception of S2GΔHR2-NPs, 5 μg ml−1 of antibody in 1× kinetic buffer was loaded onto the surface of anti-human Fc Capture Biosensors (AHC) for 300 s.
    anti-human Fc Capture Biosensors ( AHC
    suggested: None
    Correction of baseline drift was performed by subtracting the mean value of shifts recorded for a sensor loaded with antibody but not incubated with antigen and for a sensor without antibody but incubated with antigen.
    antigen .
    suggested: None
    Experimental Models: Cell Lines
    SentencesResources
    Briefly, ExpiCHO cells were thawed and incubated with ExpiCHOTM Expression Medium (Thermo Fisher) in a shaker incubator at 37 °C, 135 rpm and 8% CO2.
    ExpiCHO
    suggested: RRID:CVCL_5J31)
    SARS-CoV-1/2-pps were generated by co-transfection of HEK293T cells with the HIV-1 pNL4-3.lucR-E-plasmid (obtained from the NIH AIDS reagent program: https://www.aidsreagent.org/) and the expression plasmid encoding the S gene of SARS-CoV-1 isolate Tor2 (GenBank accession #: NC_004718) and the SARS-CoV-2 isolate Wuhan-Hu-1 (GenBank accession #: MN908947) at a 4:1 ratio by lipofectamine 3000 (Thermo Fisher Scientific).
    HEK293T
    suggested: None
    Briefly, HEK293T-hACE2 cells at 1×104 were added to each well and the plate was incubated at 37°C for 48 hours.
    HEK293T-hACE2
    suggested: None
    Experimental Models: Organisms/Strains
    SentencesResources
    Eight-week-old BALB/c mice were purchased from The Jackson Laboratory and housed in ventilated cages in environmentally controlled rooms at The Scripps Research Institute, in compliance with an approved IACUC protocol and AAALAC (Association for Assessment and Accreditation of Laboratory Animal Care) International guidelines.
    BALB/c
    suggested: RRID:IMSR_ORNL:BALB/cRl)
    Software and Algorithms
    SentencesResources
    The HEK293T-hACE2 cell line (catalogue#: NR-52511) and the vector pcDNA3.1(-) containing the SARS-CoV-2 S gene (catalogue#: NR52420) were obtained from BEI RESOURCES (https://www.beiresources.org/) and used in pseudovirus neutralization assays (72).
    https://www.beiresources.org/
    suggested: (BEI Resource Repository, RRID:SCR_013698)
    Data were retrieved from a BioTek microplate reader with Gen 5 software, the average background luminescence from a series of uninfected wells was subtracted from each well, and neutralization curves were generated using GraphPad Prism 8.4.3, in which values from wells were compared against a well containing SARS-CoV-1/2-pp only.
    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: 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: Please consider improving the rainbow (“jet”) colormap(s) used on pages 48, 50 and 52. At least one figure is not accessible to readers with colorblindness and/or is not true to the data, i.e. not perceptually uniform.

    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.

  4. Version published to 10.1101/2020.09.14.296715v1 on bioRxiv