Use of eVLP-based vaccine candidates to broaden immunity against SARS-CoV-2 variants

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Abstract

Rapid emergence of SARS-CoV-2 variants is a constant threat and a major hurdle to reach heard immunity. We produced VBI-2905a, an enveloped virus-like particle (eVLP)-based vaccine candidate expressing prefusion spike protein from the Beta variant that contains several escape mutations. VBI-2905a protected hamsters against infection with a Beta variant virus and induced high levels of neutralizing antibodies against Beta RBD. In a heterologous vaccination regimen, a single injection of VBI-2905a in animals previously immunized with VBI-2902, a vaccine candidate expressing S from ancestral SARS-CoV-2, hamsters were equally protected against Beta variant infection. As an alternate strategy to broaden immunity, we produced a trivalent vaccine expressing the prefusion spike protein from SARS-CoV-2 together with unmodifed S from SARS-CoV-1 and MERS-CoV. Relative to immunity induced against the ancestral strain, the trivalent vaccine VBI-2901a induced higher and more consistent antibody binding and neutralizing responses against a panel of variants including Beta, Delta, Kappa, and Lambda, with evidence for broadening of immunity rather than just boosting cross-reactive antibodies.

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  1. SciScore for 10.1101/2021.09.28.462109: (What is this?)

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

    Table 1: Rigor

    EthicsField Sample Permit: The animal studies were conducted under ethics protocols approved by the NRC Animal Care Committee.
    IACUC: The animal studies were conducted under ethics protocols approved by the NRC Animal Care Committee.
    IRB: The study was conducted under approval of the CCAC committee at the Vaccine and Infectious Disease Organization (VIDO) International Vaccine Centre (Saskatchewan, Canada).
    Sex as a biological variableMouse immunization study: Six- to 8-week-old female C57BL/6 mice were purchased from Charles River (St Constant, Quebec Canada).
    RandomizationMice were randomly assigned to experimental groups of 10 to 15 mice and received intraperitoneal (IP) injections with 0.5 mL of adjuvanted SARS-CoV-2 eVLPs as described elsewhere (Fluckiger, 2021).
    Blindingnot detected.
    Power Analysisnot detected.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Antibody binding titers: Anti-SARS-CoV-2 specific IgG binding titers in sera were measured by standard ELISA procedure described elsewhere (Kirchmeier et al., 2014), using recombinant SARS-CoV-2 S RBD proteins (Sinobiological).
    Anti-SARS-CoV-2
    suggested: None
    Experimental Models: Cell Lines
    SentencesResources
    Virus neutralization assays: Neutralizing activity in mouse serum samples was measured by standard plaque reduction neutralization test (PRNT) on Vero cells at the NRC using 100 PFU of SARS-CoV-2/Canada/ON/VIDO-01/2020 (Wu-1 virus) or hCoV-19/South Africa/KRISP-EC-K005321/2020 (Beta virus).
    Vero
    suggested: None
    Luciferase activity in infected hACE2-HEK293 cells was measured with a Bright-Glo Luciferase assay system (Promega) and a Beckman Coulter DTX880 plate reader.
    hACE2-HEK293
    suggested: None
    Experimental Models: Organisms/Strains
    SentencesResources
    Mouse immunization study: Six- to 8-week-old female C57BL/6 mice were purchased from Charles River (St Constant, Quebec Canada).
    C57BL/6
    suggested: None
    Recombinant DNA
    SentencesResources
    We produced infectious SARS-CoV-2pp carrying a GFP-firefly luciferase double reporter gene (plasmid pjm155, Garrone et al., 2011) instead of green fluorescent protein (GFP).
    pjm155
    suggested: None
    Software and Algorithms
    SentencesResources
    Expression of SARS-CoV-2 S, SARS-CoV-1 S, MERS-CoV S and GAG were determined by Western blot analysis (Supplementary material Fig.S1).
    GAG
    suggested: None
    Statistics: All statistical analyses were performed using GraphPad Prism 9 software (La Jolla, CA).
    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: We found the following clinical trial numbers in your paper:

    IdentifierStatusTitle
    NCT04773665Active, not recruitingSafety, Tolerability, and Immunogenicity of the COVID-19 Vac…


    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.