A COVID-19 T-Cell Response Detection Method Based on a Newly Identified Human CD8+T Cell Epitope from SARS-CoV-2—Hubei Province,China,2021

Introduction:Similar to antibody detection,severe acute respiratory syndrome coronavirus type 2(SARSCoV-2)-specific T-cell response evaluation is also pivotal among the coronavirus disease 2019(COVID-19)convalescents and the vaccinated populations.Nucleocapsid(N)protein is one of the main structural proteins of SARS-CoV-2 and can trigger T-cell responses in humans.Methods:An overlapping peptide pool covering the full length of the N protein was designed,peptides with positive T-cell activating potency in COVID-19 convalescents were screened,and CD8^(+)T cell epitopes were further identified.The epitope was used to detect the SARS-CoV-2-specific CD8^(+)T cell responses in COVID-19 convalescents based in intracellular cytokine staining and tetramer staining in flow cytometry.Results:A human leukocyte antigen A(HLAA)*1101-restricted CD8^(+)T cell epitope,which could stimulate the production of IFN-γvia peripheral blood mononuclear cells(PBMCs)of the convalescents was defined,and the tetramer generated with this epitope could detect SARS-CoV-2-specific T cells in the PBMCs of the convalescents.The structural investigation eliminated that the epitope was a typical HLA-A^(*)1101-restricted T-cell epitope which was conserved among all the sarbecoviruses.Discussion:The newly identified SARS-CoV-2-derived T-cell epitope was helpful to detect the cellular immunity against different sarbecoviruses including SARS-CoV and SARS-CoV-2.This study provided an evaluation method and also a peptide candidate for the research and development of T-cell based vaccine for the virus.