Chimeric spike mRNA vaccines protect against Sarbecovirus challenge in mice

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Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the third coronavirus that has emerged as a serious human pathogen in the past 20 years. Treatment strategies that are broadly protective against current and future SARS-like coronaviruses are needed. Martinez et al . take on this challenge by developing vaccines based on chimeras of the viral spike protein. The messenger RNA vaccines encode spike proteins composed of domain modules from epidemic and pandemic coronaviruses, as well as bat coronaviruses with the potential to cross to humans. In aged mice vulnerable to infection, the chimeric vaccines protected against challenge from SARS-CoV, SARS-CoV-2 and tested variants of concern, and zoonotic coronaviruses with pandemic potential. —VV

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  1. SciScore for 10.1101/2021.03.11.434872: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board StatementIACUC: The study was carried out in accordance with the recommendations for care and use of animals by the Office of Laboratory Animal Welfare (OLAW), National Institutes of Health and the Institutional Animal Care and Use Committee (IACUC) of University of North Carolina (UNC permit no. A-3410-01).
    RandomizationIn a blinded manner, three random fields of lung tissue were chosen and scored for the following: (A) neutrophils in the alveolar space (none = 0, 1–5 cells = 1, > 5 cells = 2), (B) neutrophils in the interstitial septa (none = 0, 1–5 cells = 1, > 5 cells = 2), (C) hyaline membranes (none = 0, one membrane = 1, > 1 membrane = 2), (D) Proteinaceous debris in air spaces (none = 0, one instance = 1, > 1 instance = 2), (E) alveolar septal thickening (< 2x mock thickness = 0, 2–4x mock thickness = 1, > 4x mock thickness = 2).
    BlindingAnalyses and scoring were performed by a board vertified veterinary pathologist who was blinded to the treatment groups as described previously (36).
    Power Analysisnot detected.
    Sex as a biological variableAnimals, immunizations, and challenge viruses: Eleven-month-old female BALB/c mice were purchased from Envigo (#047) and were used for all experiments.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    HRP conjugated goat anti-mouse IgG secondary antibody (SouthernBiotech 1030-05) was diluted to 1:10,000 in assay diluent without azide, incubated at for 1 hour at room temperature, washed and detected with 20μl SureBlue Reserve (KPL 53-00-03) for 15 minutes.
    anti-mouse IgG
    suggested: (SouthernBiotech Cat# 1030-05, RRID:AB_2619742)
    Antibody-virus and virus only mixtures were then incubated at 37°C with 5% CO2 for one hour.
    Antibody-virus
    suggested: None
    Experimental Models: Cell Lines
    SentencesResources
    Virus titers were measured in Vero E6 USAMRIID cells, as defined by plaque forming units (PFU) per ml, in a 6-well plate format in quadruplicate biological replicates for accuracy.
    Vero E6
    suggested: None
    Experimental Models: Organisms/Strains
    SentencesResources
    Animals, immunizations, and challenge viruses: Eleven-month-old female BALB/c mice were purchased from Envigo (#047) and were used for all experiments.
    BALB/c
    suggested: None
    Software and Algorithms
    SentencesResources
    Statistics: All statistical analyses were performed using GraphPad Prism 9.
    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:
    A caveat of including multiple chimeric spikes in a single shot is the potential formation of heterotrimers not present in the intended vaccine formulation. While it remains unknown if our chimeric mRNA-LNP vaccines generate heterotrimers in vivo, the robustness of the cross-neutralizing titers against sarbecoviruses and protection against SARS-CoV and SARS-CoV-2 in groups 1 and 2 in aged mice lends support to this strategy as a way to elicit broadly cross-reactive neutralizing antibodies against Group 2B coronaviruses. In agreement with this notion, chimera 4, which contains the RsSHC014 RBD and SARS-CoV-2 NTD and S2, elicited binding and neutralizing antibodies and also fully protected mice from BtCoV RsSHC014 and SARS-CoV-2 challenge, suggesting that CoV spikes vaccines can be designed to maximize their display of neutralizing and protective epitopes that can cover more than one pandemic/epidemic/pre-emergent CoV that are at high risk for emergence into naïve human populations. While other strategies also exist, such as multiplexing mosaic sarbecovirus RBDs (19), S1 or spike glycoproteins and RBDs on nanoparticles (45), chimeric spike mRNA-LNP vaccination can clearly achieve broad protection, using existing manufacturing technologies, and are highly portable to other high-risk emerging coronaviruses like group 2C MERS-CoV-related strains. It is notable that our chimeric spike vaccines and the SARS-CoV-2 furin KO, all of which lacked the two proline stabilizing mutations (S...

    Results from TrialIdentifier: No clinical trial numbers were referenced.


    Results from Barzooka: We found bar graphs of continuous data. We recommend replacing bar graphs with more informative graphics, as many different datasets can lead to the same bar graph. The actual data may suggest different conclusions from the summary statistics. For more information, please see Weissgerber et al (2015).


    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.