Disruption of nasal bacteria enhances protective immune responses to influenza A virus and SARS-CoV-2 infection in mice

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Abstract

Gut microbiota plays a critical role in the induction of adaptive immune responses to influenza virus infection. However, the role of nasal bacteria in the induction of the virus-specific adaptive immunity is less clear. Here we demonstrate that while intranasal administration of influenza virus hemagglutinin vaccine alone was insufficient to induce the vaccine-specific antibody responses, disruption of nasal bacteria by lysozyme or addition of culturable oral bacteria from a healthy human volunteer rescued inability of the nasal bacteria to generate antibody responses to intranasally administered the split-virus vaccine. Myd88-depdnent signaling in the hematopoietic compartment was required for adjuvant activity of intranasally administered oral bacteria. In addition, we found that the oral bacteria-combined intranasal vaccine induced protective antibody response to influenza virus and SARS-CoV-2 infection. Our findings here have identified a previously unappreciated role for nasal bacteria in the induction of the virus-specific adaptive immune responses.

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  1. SciScore for 10.1101/2020.12.25.424300: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board StatementIACUC: All animal experiments were performed in accordance with the University of Tokyo’s Regulations for Animal Care and Use, which were approved by the Animal Experiment Committee of the Institute of Medical Science, the University of Tokyo (approval number PA17– 69).
    IRB: The research protocol was approved by the Research Ethics Review Committee of the Institute of Medical Science, the University of Tokyo (approval number 2019-42-1121).
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variableFor intranasal infection, one-month-old female Syrian hamsters (Japan SLC Inc.) were fully anesthetized by i.p. injection of pentobarbital sodium (Somnopentyl, Kyoritsu Seiyaku Co., Ltd., Tokyo, Japan) and then infected intranasally with 2×106 pfu (in 100 μL) of SARS-CoV-2.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Standards for PR8- or HA-reactive IgA and IgG antibody titration were prepared from the nasal wash or serum of the virus-infected or vaccinated mice, and expressed as the same arbitrary units (160-unit).
    HA-reactive IgA and IgG
    suggested: None
    Experimental Models: Cell Lines
    SentencesResources
    Cells: Madin-Darby canine kidney (MDCK) cells were grown in Eagle’s minimal essential medium (E-MEM; Nacalai Tesque) supplemented with 10% fetal bovine serum (FBS), penicillin (100 U/ml), and streptomycin (100 μg/ml).
    MDCK
    suggested: None
    VeroE6 cells stably expressing transmembrane protease serine 2 (VeroE6/TMPRSS2; JCRB Cell Bank 1819) were maintained in Dulbecco’s modified Eagle’s medium (DMEM) low glucose (Cat#08456-65; Nacalai Tesque) supplemented with 10% FBS, penicillin (100 U/ml), streptomycin (100 μg/ml), and G418 (1mg/ml) (Matsuyama et al., 2020).
    VeroE6
    suggested: JCRB Cat# JCRB1819, RRID:CVCL_YQ49)
    The infectious titer was determined by a standard plaque assay using VeroE6/TMPRSS2 cells, as described previously (Imai et al., 2020).
    VeroE6/TMPRSS2
    suggested: JCRB Cat# JCRB1819, RRID:CVCL_YQ49)
    Experimental Models: Organisms/Strains
    SentencesResources
    Mice: Age- and sex-matched Balb/c mice obtained from Japan SLC, Inc. were used as WT controls.
    Balb/c
    suggested: RRID:IMSR_ORNL:BALB/cRl)
    MyD88-deficient Balb/c mice were a gift from T. Taniguchi.
    MyD88-deficient Balb/c
    suggested: None
    WT and MyD88-deficient mice were γ-irradiated with 6 Gy, then were reconstituted with 5 × 106 bone marrow cells of the appropriate genotype via i.v. injection and allowed to recover for 8 weeks before vaccination.
    MyD88-deficient
    suggested: None
    Software and Algorithms
    SentencesResources
    Quantification and statistical analysis: Statistical significance was tested by one-way ANOVA followed by Tukey test or unpaired t tests with PRISM software (Version 5; GraphPad software).
    PRISM
    suggested: (PRISM, RRID:SCR_005375)
    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: 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: 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.