Fig. 2

Identification of HLA-A*24:02-binding peptides derived from SARS-CoV-2. A IFN-γ ELISPOT assay was performed after in vitro CTL induction. CD8⁺ T cells and HLA-A*24:02-positive TISI cells pulsed with each peptide were co-cultured overnight. TISI cells without the peptide were used as negative control. Bars represent the number of IFN-γ spots. CD8⁺ T cell responses were judged as positive when the number of IFN-γ spots were 1.5 times or higher than the negative control (P01, P02, P04, P06, P07, P08, P09, P11, and P12). Representative positive activities to P02, P06, P08, and P12 observed in PBMCs from two donors are shown. No positive response was observed for P03, P05, P10, P13, and P14 in two PBMCs. Spot counts higher than 200 are demonstrated as “too numerous to count (TNTC)”. B To confirm the response of CTLs to SARS-CoV-2-derived peptides, IFN-γ ELISA was performed. CTLs (Responders) were co-cultured overnight with TISI cells (Stimulators) pulsed with or without the peptide at the indicated ratio of Responders to Stimulators (R/S ratio). IFN-γ secretion was measured by ELISA. CTLs that revealed the peptide-specific IFN-γ secretion for eight peptides are shown. Similar results were obtained in independent experiments using three CTLs in the respective peptides