Intranasal HD-Ad vaccine protects the upper and lower respiratory tracts of hACE2 mice against SARS-CoV-2

  1. Huibi Cao
  2. Juntao Mai
  3. Zhichang Zhou
  4. Zhijie Li
  5. Rongqi Duan
  6. Jacqueline Watt
  7. Ziyan Chen
  8. Ranmal Avinash Bandara
  9. Ming Li
  10. Sang Kyun Ahn
  11. Betty Poon
  12. Natasha Christie-Holmes
  13. Scott D. Gray-Owen
  14. Arinjay Banerjee
  15. Karen Mossman
  16. Rob Kozak
  17. Samira Mubareka
  18. James M. Rini
  19. Jim Hu
  20. Jun Liu

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Abstract

Background

The ongoing COVID-19 pandemic has resulted in 185 million recorded cases and over 4 million deaths worldwide. Several COVID-19 vaccines have been approved for emergency use in humans and are being used in many countries. However, all the approved vaccines are administered by intramuscular injection and this may not prevent upper airway infection or viral transmission.

Results

Here, we describe a novel, intranasally delivered COVID-19 vaccine based on a helper-dependent adenoviral (HD-Ad) vector. The vaccine (HD-Ad_RBD) produces a soluble secreted form of the receptor binding domain (RBD) of the SARS-CoV-2 spike protein and we show it induced robust mucosal and systemic immunity. Moreover, intranasal immunization of K18-hACE2 mice with HD-Ad_RBD using a prime-boost regimen, resulted in complete protection of the upper respiratory tract against SARS-CoV-2 infection.

Conclusion

Our approaches provide a powerful platform for constructing highly effective vaccines targeting SARS-CoV-2 and its emerging variants.

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  1. Version published to 10.1186/s13578-021-00723-0
  2. ScreenIT

    SciScore for 10.1101/2021.04.08.439006: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board StatementIACUC: All work with infectious SARS-CoV-2 was performed in the Containment Level 3 (CL-3) facilities at University of Toronto using appropriate protective equipment and procedures approved by the Institutional Biosafety Committee.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variableImmunization of BALB/c mice: Female BALB/c mice were intranasally immunized with different doses (108 to 1010 viral particles) of HD-Ad_RBD or the HD-Ad vector control (HD-C4HSU) in 20 μl of PBS containing 40 μg/ml of DEAE-Dextran and 0.1% LPC.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Antibodies including goat anti-mouse IgG horseradish peroxidase (HRP)-conjugated (31430 thermo) and anti-mouse IgA HRP-conjugated (626720 Invitrogen) were diluted 1:5000, or 1:200 in blocking solution.
    anti-mouse IgG
    suggested: (Thermo Fisher Scientific Cat# 31430, RRID:AB_228307)
    anti-mouse IgA
    suggested: (Innovative Research Cat# 62-6720, RRID:AB_138466)
    After blocking with FcγIII and FcγII receptors antibody (BD Pharmingen, 553142), cells were stained with live/dead fixable cell stain (Invitrogen 34955), CD44 BV510, CD4 BV711, and CD8a APC-Cy™7 (BD) antibodies.
    CD44
    suggested: None
    CD4
    suggested: None
    Experimental Models: Cell Lines
    SentencesResources
    Serial 10-fold dilutions of the lung homogenates were then added into the monolayer Vero-E6 cells.
    Vero-E6
    suggested: None
    Experimental Models: Organisms/Strains
    SentencesResources
    BALB/c and K18-hACE2 C57BL/6 mice were purchased from The Jackson Laboratory.
    C57BL/6
    suggested: None
    K18-hACE2 mice were bred in house and each mouse was genotyped before use.
    K18-hACE2
    suggested: RRID:IMSR_GPT:T037657)
    Immunization of BALB/c mice: Female BALB/c mice were intranasally immunized with different doses (108 to 1010 viral particles) of HD-Ad_RBD or the HD-Ad vector control (HD-C4HSU) in 20 μl of PBS containing 40 μg/ml of DEAE-Dextran and 0.1% LPC.
    BALB/c
    suggested: None
    Software and Algorithms
    SentencesResources
    Cells were analysed on a Becton Dickinson LSR II CFI (SickKids Flow Cytometry Facility), using Flowjo x 10.0 software.
    Flowjo
    suggested: (FlowJo, RRID:SCR_008520)

    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:
    However, one of the major limitations in the use of these vectors for therapeutic purposes is the transient nature of the transgene expression and the systemic toxicity, which are both due to inflammatory and immune responses triggered by the residual expression of viral proteins40–42. To overcome these problems, HD-Ad, the third generation of Ad vectors, with all viral coding sequences deleted, was used in our study. HD-Ad minimizes the host immune response to the vector and allows long-term expression of the transgene in host tissues or organs, thereby providing a safer and more efficient way for gene delivery and transgene expression30–34. Consistently, we detected high level expression of the RBD in transfected cells and the majority of the protein was secreted, which ensures efficient antigen-dependent stimulation of the host immune system. Consequently, the HD-Ad_RBD vaccine induced extremely high levels of antigen-specific antibody response. For example, the IgG reciprocal GMT in sera reached 1,837,920 even though we used a moderate dose of the vaccine (5×109 viral particles) for vaccination. We also detected high levels of neutralizing antibody against the SARS-CoV-2 virus, and the reciprocal ID50 GMT was close to 1,000, which is in the same range of the neutralizing antibody induced by the two mRNA vaccines (mRNA-1273, BNT162b2) described above. The superior safety profile of HD-Ad allows us to deliver the vaccine by an intranasal route. Compared to intramuscular inj...

    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

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  3. Version published to 10.1101/2021.04.08.439006v1 on bioRxiv