Fig. 1. Experimental scheme and frequencies of CD8⁺ T cell recognizing six epitopes of nucleocapsid protein of SARS-CoV-2.

a Overview of experimental design. Image created using BioRender.com. b Anti-nucleocapsid IgG titers in uninfected and convalescent donors. Anti-nucleocapsid IgG were measured using ELISA. Samples with concentrations below 1.0 AU/mL were undetectable for IgG antibodies (convalescent = 75 and uninfected = 138). c Significant differences in CD127, CD28, and CD27 expression in CD8⁺ T cells between uninfected and convalescent donors (C = Convalescent, n = 118, U = Uninfected, n = 56). PBMCs were isolated from blood and were stained with a panel of 15 antibodies. d Information on six SARS-CoV-2 nucleocapsid epitopes. e Frequencies of CD8⁺ T cells recognizing six nucleocapsid epitopes in uninfected and convalescent donors (Convalescent = 35 and Uninfected = 80). Each epitope specific tetramer was used to measure the frequency of epitope recognizing CD8⁺ T cells in PBMCs by flow cytometry. The sum refers to the summation of the frequencies of CD8⁺ T cells for all six nucleocapsid epitopes. f Frequencies of CD8⁺ T cell central memory (T_CM defined by CD62⁺CD45RA⁻) subset that recognizes six nucleocapsid epitopes (Convalescent n = 35, Uninfected n = 80). Two-tailed T test adjusted for age and sex were was carried out for all comparisons between convalescent and uninfected donor. p value, mean and SEM are shown.