A SARS CoV-2 nucleocapsid vaccine protects against distal viral dissemination

  1. Jacob Class
  2. Tanushree Dangi
  3. Justin M. Richner
  4. Pablo Penaloza-MacMaster

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Abstract

The SARS CoV-2 pandemic has killed millions of people. This viral infection can also result in substantial morbidity, including respiratory insufficiency and neurological manifestations, such as loss of smell and psychiatric diseases. Most SARS CoV-2 vaccines are based on the spike antigen, and although they have shown extraordinary efficacy at preventing severe lung disease and death, they do not always confer sterilizing immune protection. We performed studies in K18-hACE2 mice to evaluate whether the efficacy of SARS CoV-2 vaccines could be augmented by incorporating nucleocapsid as a vaccine antigen. We vaccinated mice with adenovirus-based vaccines encoding spike antigen alone, nucleocapsid antigen alone, or combined spike and nucleocapsid antigens. Mice were then challenged intranasally with SARS CoV-2, and acute viral loads were quantified at a proximal site of infection (lung) and a distal site of infection (brain). Interestingly, the spike-based vaccine conferred acute protection in the lung, but not in the brain. The spike-based vaccine conferred acute protection in the brain only if combined with the nucleocapsid-based vaccine. These findings suggest that nucleocapsid-specific immunity is important for the distal control of SARS CoV-2, warranting the inclusion of nucleocapsid in next-generation COVID-19 vaccines.

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  1. ScreenIT

    SciScore for 10.1101/2021.04.26.440920: (What is this?)

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

    Table 1: Rigor

    EthicsIACUC: Mouse infectious were performed at the University of Illinois at Chicago (UIC) following BL3 guidelines with approval by the UIC Institutional Animal Care and Use Committee (IACUC).
    Sex as a biological variableApproximately half were males and half were females.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Cells were stained with fluorescently-labeled antibodies against CD8α (53-6.7 on PerCP-Cy5.5), CD44 (IM7 on Pacific Blue), KbVL8 or IFNγ (XMG1.2) on APC.
    CD8α
    suggested: None
    IFNγ
    suggested: None
    Fluorescently-labeled antibodies were purchased from BD Pharmingen, except for anti-CD44 (which was from Biolegend).
    anti-CD44
    suggested: None
    Experimental Models: Cell Lines
    SentencesResources
    The Ad5 vectors were propagated on trans-complementing HEK293 cells (ATCC), purified by cesium chloride density gradient centrifugation, titrated, and then frozen at −80 °C.
    HEK293
    suggested: CLS Cat# 300192/p777_HEK293, RRID:CVCL_0045)
    Virus was propagated and tittered on Vero-E6 cells.
    Vero-E6
    suggested: None
    Experimental Models: Organisms/Strains
    SentencesResources
    Mice and vaccinations: 6-8-week-old K18-hACE2 mice were used.
    K18-hACE2
    suggested: RRID:IMSR_GPT:T037657)
    Recombinant DNA
    SentencesResources
    Sergii Pshenychnyi using a plasmid that was produced under HHSN272201400008C and obtained through BEI Resources, NIAID, NIH: Vector pCAGGS Containing the SARS-Related Coronavirus 2, Wuhan-Hu-1 Spike Glycoprotein Gene (soluble, stabilized), NR-52394.
    pCAGGS
    suggested: RRID:Addgene_18926)
    Software and Algorithms
    SentencesResources
    Flow cytometry samples were acquired with a Becton Dickinson Canto II or an LSRII and analyzed using FlowJo (Treestar).
    FlowJo
    suggested: (FlowJo, RRID:SCR_008520)
    Data were analyzed using Prism (Graphpad).
    Prism
    suggested: (PRISM, RRID:SCR_005375)
    Graphpad
    suggested: (GraphPad, RRID:SCR_000306)

    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 limitation of our study is that we only measured viral loads at a very early timepoint (72 hr post-challenge). We did not compare viral loads at other time points, because unvaccinated animals succumb by day 6 post-challenge19, and because it is known that spike-based vaccination elicits immune responses that ultimately clear SARS CoV-2 within a week of challenge30,31. Our study was focused on evaluating acute viral control at a very early time post-challenge. Future studies will determine whether these findings generalize to other vaccine platforms besides adenovirus-based vectors (e.g. mRNA vaccines encoding nucleocapsid), and whether other virus-specific immune responses (e.g. envelope-, membrane-specific) can improve further distal protection. Although the K18-hACE2 model is considered useful to evaluate vaccines and antivirals, the extensive acute viral dissemination observed in brain may be a peculiarity of this mouse model. Nevertheless, it is still reasonable to conclude that nucleocapsid-specific immunity improves distal viral control of SARS CoV-2. In conclusion, we show a substantial benefit of including both spike and nucleocapsid antigens in COVID-19 vaccines. These results warrant the incorporation of nucleocapsid as a critical antigen in future coronavirus vaccines.

    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.
    • No funding statement was detected.
    • No protocol registration statement was detected.

    Results from scite Reference Check: We found no unreliable references.

    About SciScore

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  2. Version published to 10.1101/2021.04.26.440920 on bioRxiv