Recombinant protein subunit SARS-CoV-2 vaccines formulated with CoVaccine HT™ adjuvant induce broad, Th1 biased, humoral and cellular immune responses in mice

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Abstract

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  1. SciScore for 10.1101/2021.03.02.433614: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board StatementIACUC: All experimental procedures were reviewed and approved by the Institutional Animal Care and Use Committee (IACUC) at the University of Hawaii at Manoa (UHM) and carried out in the UHM American Association for Accreditation of Laboratory Animal Care (AAALAC) accredited Laboratory Animal Facility
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    For this, the monoclonal antibody (mAb) CR3022 (provided by Mapp Biopharmaceutical) was coupled to NHS-activated Sepharose at a concentration of 10 mg/mL and used for IAC in tandem with a HiPrep 26/10 Desalting column (Cytiva, Marlborough, MA) equilibrated with PBS allowing quick buffer exchange of the eluted protein from low pH buffer into PBS. 2.3 Mouse experiments: Groups (n=7 or 15 per group) of 7 to 10-week-old Swiss Webster mice of both sexes (bred from original breeding stocks obtained from Taconic Biosciences, Germantown, NY) were immunized intramuscularly (i.m.) at days 0 and 21 with 5 μg of SARS-CoV-2 spike proteins SdTM or SdTM2P (purified by hACE2 affinity chromatography) alone or in combination with 1 mg of CoVaccine HT™ adjuvant (Protherics Medicines Development Ltd, a BTG company, London, United Kingdom).
    CR3022
    suggested: (Imported from the IEDB Cat# CR3022, RRID:AB_2848080)
    Following two washes with MIA buffer (1% BSA and 0.02 % Tween 20 in 1x PBS), 50μl of 1μg/mL red phycoerythrin (R-PE)-conjugated goat anti-mouse IgG antibodies (Jackson ImmunoResearch, Inc., West Grove, PA) were added and incubated at 37°C for another 1 hour.
    anti-mouse IgG
    suggested: None
    The IgG subclass profile in serum samples was analyzed using IgG subclass-specific secondary antibodies (Southern Biotech, Birmingham, AL), and the ratios of IgG2a/IgG1 and IgG2b/IgG1 were calculated using the MFI readouts at the serum dilution (1:2000) that is within the linear range of the antibody binding standard curve.
    IgG subclass-specific secondary antibodies (Southern Biotech, Birmingham, AL)
    suggested: None
    2.8 Statistical analysis: Statistical analysis was performed using one sample t test or Mann-Whitney t test to compare the neutralization titers, IgG subclass antibody profile, and IFN-γ secreting response between adjuvanted and unadjuvanted groups.
    IgG subclass antibody profile,
    suggested: None
    Experimental Models: Cell Lines
    SentencesResources
    The gene was also codon-optimized for expression in Drosophila S2 cells, with an altered furin cleavage site (RRAR changed to GSAR) between S1 and S2 domains to prevent cleavage, and contains a trimerization domain of T4 bacteriophage fibritin (foldon) at the C-terminus.
    S2
    suggested: TKG Cat# TKG 0245, RRID:CVCL_4719)
    Virus titers were measured on Vero E6 cells in 6-well plates by standard plaque assay.
    Vero E6
    suggested: None
    Software and Algorithms
    SentencesResources
    For this, the monoclonal antibody (mAb) CR3022 (provided by Mapp Biopharmaceutical) was coupled to NHS-activated Sepharose at a concentration of 10 mg/mL and used for IAC in tandem with a HiPrep 26/10 Desalting column (Cytiva, Marlborough, MA) equilibrated with PBS allowing quick buffer exchange of the eluted protein from low pH buffer into PBS. 2.3 Mouse experiments: Groups (n=7 or 15 per group) of 7 to 10-week-old Swiss Webster mice of both sexes (bred from original breeding stocks obtained from Taconic Biosciences, Germantown, NY) were immunized intramuscularly (i.m.) at days 0 and 21 with 5 μg of SARS-CoV-2 spike proteins SdTM or SdTM2P (purified by hACE2 affinity chromatography) alone or in combination with 1 mg of CoVaccine HT™ adjuvant (Protherics Medicines Development Ltd, a BTG company, London, United Kingdom).
    Mapp Biopharmaceutical
    suggested: None
    The resulting MFI values were analyzed using a sigmoidal dose-response, variable slope model (GraphPad Prism, San Diego, CA), with antibody concentrations transformed to log10 values.
    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: We detected the following sentences addressing limitations in the study:
    The urgent need to rapidly vaccinate the human population worldwide both to slow the increase in fatalities and to prevent the emergence of escape mutations sharply highlights the limitations of vaccines requiring stringent cold chains as even under the best conditions, doses are lost due to inadequate storage or handling. The use of protein subunit vaccines not only offers additional vaccines to be used in parallel to rapidly immunize the global population, but also offers an easier opportunity to develop thermostabilized vaccines which would simplify rapid and far-flung delivery. Using recombinant spike protein without the transmembrane domain and with pre-fusion complex stabilization, we have demonstrated robust immune responses with the CoVaccine HT™ adjuvant in an outbred mouse model. This immune response is observed within 7 days of the first dose and peaks within 14 days after the second dose, showing robust humoral and cell mediated immunity. The immune response was potent with as little as 2.5 μg of protein and 0.3 mg of adjuvant, indicating an economical dose-sparing format should be feasible and should include testing of thermostabilized formulations in rodents and other species.

    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.

    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.