Genetic and structural basis for recognition of SARS-CoV-2 spike protein by a two-antibody cocktail

This article has been Reviewed by the following groups

Read the full article See related articles

Abstract

The SARS-CoV-2 pandemic has led to an urgent need to understand the molecular basis for immune recognition of SARS-CoV-2 spike (S) glycoprotein antigenic sites. To define the genetic and structural basis for SARS-CoV-2 neutralization, we determined the structures of two human monoclonal antibodies COV2-2196 and COV2-2130 1 , which form the basis of the investigational antibody cocktail AZD7442, in complex with the receptor binding domain (RBD) of SARS-CoV-2. COV2-2196 forms an “aromatic cage” at the heavy/light chain interface using germline-encoded residues in complementarity determining regions (CDRs) 2 and 3 of the heavy chain and CDRs 1 and 3 of the light chain. These structural features explain why highly similar antibodies (public clonotypes) have been isolated from multiple individuals 1–4 . The structure of COV2-2130 reveals that an unusually long LCDR1 and HCDR3 make interactions with the opposite face of the RBD from that of COV2-2196. Using deep mutational scanning and neutralization escape selection experiments, we comprehensively mapped the critical residues of both antibodies and identified positions of concern for possible viral escape. Nonetheless, both COV2-2196 and COV2-2130 showed strong neutralizing activity against SARS-CoV-2 strain with recent variations of concern including E484K, N501Y, and D614G substitutions. These studies reveal germline-encoded antibody features enabling recognition of the RBD and demonstrate the activity of a cocktail like AZD7442 in preventing escape from emerging variant viruses.

Article activity feed

  1. SciScore for 10.1101/2021.01.27.428529: (What is this?)

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

    Table 1: Rigor

    NIH rigor criteria are not applicable to paper type.

    Table 2: Resources

    Antibodies
    SentencesResources
    The bound antibodies were detected using goat antihuman IgG conjugated with horseradish peroxidase (Southern Biotech) and TMB substrate (Thermo Fischer Scientific).
    antihuman IgG
    suggested: (GeneTex Cat# GTX28798, RRID:AB_374523)
    After the antibody incubations, the libraries were secondarily labeled with 1:100 FITC-conjugated anti-MYC antibody (Immunology Consultants Lab, CYMC-45F) to label for RBD expression and 1:200 PE-conjugated goat anti-human-IgG (Jackson ImmunoResearch 109-115-098) to label for bound antibody.
    anti-MYC
    suggested: None
    anti-human-IgG
    suggested: None
    For each antibody selection, we computed the “escape fraction” for each barcoded variant using the deep sequencing counts for each variant in the original and antibody-escape populations and the total fraction of the library that escaped antibody binding via a previously described formula27.
    antibody-escape
    suggested: None
    Note that these filtering criteria are slightly more stringent than those previously used to map a panel of human antibodies27 but are identical to those used in recent studies defining RBD residues that impact the binding of mAbs65 and polyclonal serum40.
    antibodies27
    suggested: None
    Software and Algorithms
    SentencesResources
    The diffraction data were processed with XDS59 and CCP4 suite60.
    CCP4
    suggested: (CCP4, RRID:SCR_007255)
    PyMOL software64 was used to make all of the structural figures.
    PyMOL
    suggested: (PyMOL, RRID:SCR_000305)
    Additionally, the germline revertant forms of COV2-2196 were generated by aligning the sequence to identified germline sequences using IgBlast, and reverting back the residues that were not germline-encoded.
    IgBlast
    suggested: (IgBLAST, RRID:SCR_002873)

    Results from OddPub: Thank you for sharing your code and data.


    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.