Rationally designed immunogens enable immune focusing to the SARS-CoV-2 receptor binding motif

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Abstract

Eliciting antibodies to surface-exposed viral glycoproteins can lead to protective responses that ultimately control and prevent future infections. Targeting functionally conserved epitopes may help reduce the likelihood of viral escape and aid in preventing the spread of related viruses with pandemic potential. One such functionally conserved viral epitope is the site to which a receptor must bind to facilitate viral entry. Here, we leveraged rational immunogen design strategies to focus humoral responses to the receptor binding motif (RBM) on the SARS-CoV-2 spike. Using glycan engineering and epitope scaffolding, we find an improved targeting of the serum response to the RBM in context of SARS-CoV-2 spike imprinting. Furthermore, we observed a robust SARS-CoV-2-neutralizing serum response with increased potency against related sarbecoviruses, SARS-CoV, WIV1-CoV, RaTG13-CoV, and SHC014-CoV. Thus, RBM focusing is a promising strategy to elicit breadth across emerging sarbecoviruses and represents an adaptable design approach for targeting conserved epitopes on other viral glycoproteins.

One Sentence Summary

SARS-CoV-2 immune focusing with engineered immunogens

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  1. SciScore for 10.1101/2021.03.15.435440: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board StatementIACUC: All experiments were conducted with institutional IACUC approval (MGH protocol 2014N000252).
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variableImmunizations: All immunizations were performed using female C57BL/6 mice (Jackson Laboratory) aged 6-10 weeks.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    150 μL of HRP-conjugated rabbit anti-mouse IgG antibody, sourced commercially from Abcam (at a 1:20,000 dilution in PBS), was used for the secondary incubation.
    anti-mouse IgG
    suggested: None
    Experimental Models: Cell Lines
    SentencesResources
    Expi 293F cells (ThermoFisher) were used to express proteins.
    293F
    suggested: RRID:CVCL_D615)
    Transient transfection of 293T cells was used to generate lentiviral particles.
    293T
    suggested: NCBI_Iran Cat# C498, RRID:CVCL_0063)
    Following incubation, 10,000 293T-ACE2 cells (37) in 20 μL of media containing 15 μg/mL polybrene was introduced to each well.
    293T-ACE2
    suggested: RRID:CVCL_YZ65)
    Experimental Models: Organisms/Strains
    SentencesResources
    Immunizations: All immunizations were performed using female C57BL/6 mice (Jackson Laboratory) aged 6-10 weeks.
    C57BL/6
    suggested: None
    Software and Algorithms
    SentencesResources
    Gblocks were then cloned into pVRC and sequence confirmed via Genewiz.
    Genewiz
    suggested: (GENEWIZ, RRID:SCR_003177)
    FlowJo (version 10) was used to analyze FCS files.
    FlowJo
    suggested: (FlowJo, RRID:SCR_008520)
    Nonlinear regressions were fitted to the data using GraphPad Prism (version 9), allowing IC50 values to be calculated via the interpolated 50% inhibitory concentration.
    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: 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.