Beyond Spike: Identification of nine highly prevalent SARS-CoV-2-specific CD8 T-cell epitopes in a large Norwegian cohort

This article has been Reviewed by the following groups

Read the full article See related articles

Discuss this preprint

Start a discussion What are Sciety discussions?

Abstract

T-cell epitopes with broad population coverage may form the basis for a new generation of SARS-CoV-2 vaccines. However, published studies on immunoprevalence are limited by small test cohorts, low frequencies of antigen-specific cells and lack of data correlating eluted HLA ligands with T-cell responsiveness. As the protective role of pre-existing cross-reactivity to homologous peptides is unclear, we aimed to identify SARS-CoV-2-specific minimal epitopes recognized by CD8 T-cells among 48 peptides eluted from prevalent HLA alleles, and an additional 84 predicted binders, in a large cohort of convalescents (n=83) and pre-pandemic control samples (n=19). We identified nine conserved SARS-CoV-2-specific epitopes restricted by four of the most prevalent HLA class I alleles in the Norwegian study cohort, to which responding CD8 T cells were detected in 70-100% of convalescents expressing the relevant HLA allele. Only two of these were derived from the Spike protein, included in current vaccines. We found a strong correlation between immunoprevalence and immunodominance. Thus, the CD8 T-cell response to SARS-CoV-2 is more focused than previously believed. Using a new algorithm, we predict that a vaccine including these epitopes could induce a T-cell response in 83% of Caucasians.

Article activity feed

  1. SciScore for 10.1101/2021.10.13.463911: (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
    Three convalescents for whom a PCR test was lacking were included based on positive anti-RBD and anti-Nucleocapsid antibodies.
    anti-RBD
    suggested: None
    anti-Nucleocapsid
    suggested: None
    There were no differences between convalescent individuals who had been hospitalized due to COVID-19 as compared to those who had not with respect to SARS-CoV-2 antibody titers or functional CD4 and CD8 T cell responses to peptide pools (Suppl Fig. 1B and 2C).
    SARS-CoV-2
    suggested: None
    Plasma antibody titer determination: A multiplexed bead-based flow cytometric assay, referred to as microsphere affinity proteomics (MAP), was adapted for detection of SARS-CoV-2 antibodies50.
    antibodies50
    suggested: None
    After staining with a PE anti-human HLA-A,B,C antibody, stable HLA expressing cell lines were sorted using the Sony SH800 cell sorter.
    anti-human HLA-A
    suggested: None
    Subsequently, surface staining was performed by adding the following antibodies: PerCP/Cyanine5.5 anti-human CD3, Alexa Fluor® 700 anti-human CD4, FITC anti-human CD8a, BV605 anti-human HLA-DR,
    anti-human CD3
    suggested: None
    anti-human CD4
    suggested: None
    anti-human HLA-DR
    suggested: None
    Thereafter the following antibodies and LD-NIR (1:1000) were added to the sample for 30min at 4°C: FITC anti-human CD8a,
    LD-NIR
    suggested: None
    anti-human CD8a
    suggested: None
    Subsequently, surface staining was performed by adding the following antibodies: PE anti-human-CD8a,
    anti-human-CD8a
    suggested: None
    Software and Algorithms
    SentencesResources
    BV785 anti-human CD38, BV421 anti-human CD69 together with Live/Dear-near IR (1:1000; LD-NIR; ThermoFisher Scientific; Cat no L10119) for exclusion of dead cells.
    ThermoFisher Scientific
    suggested: None
    24 h after UV-exchange, the following streptavidin-tagged fluorochromes were added at optimized ratios to the pMonomer solution: SA-PE (Invitrogen; Cat no S866; Lot no 2129894); SA-APC (Invitrogen; Cat no S868; Lot no 2105223), SA-BV421 (Biolegend; Cat no 405229; Lot no B202410), SA-BV605 (Biolegend; Cat no 405225; Lot no B267737), SA-BV421 (Biolegend; Cat no 405229; Lot no B202410), SA-PE Cy7 (BD Biosciences; Cat no 557598; Lot no 7325636), SA-PE-CF594 (BD Biosciences; Cat no 562284; Lot no 7138598), SA-PE-Cy5 (BD Biosciences; Cat no 554062; Lot no 7066693), SA-APC-R700 (BD Biosciences; Cat no 565144; Lot no 7179560), SA-BB790-P (BD Biosciences; prototype kindly provided by Bob Balderas from BD Biosciences; Lot no 8124567).
    BD Biosciences
    suggested: (BD Biosciences, RRID:SCR_013311)
    Peptide sequence alignment with human common cold coronaviruses: Homology calculations were performed by aligning the sequence of SARS-CoV-2 epitopes with the corresponding protein sequences of common cold coronaviruses (OC43, NL63, HKU1,229E) using the Clustal Omega tool with default parameters.
    Clustal Omega
    suggested: (Clustal Omega, RRID:SCR_001591)
    Data analysis and statistics: Flow cytometry data acquired on different BD Biosciences instruments were analyzed using FlowJo (TreeStar) version 10.6.2 software.
    FlowJo
    suggested: (FlowJo, RRID:SCR_008520)
    Statistical analysis was performed in R version 4.0.4 and GraphPad Prism version 8.3.0.
    GraphPad Prism
    suggested: (GraphPad Prism, RRID:SCR_002798)

    Results from OddPub: Thank you for sharing your 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.

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


    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.