Fig. 1.

IFNγ ELISpot results for SARS-specific memory T cell screening. PBMCs from (A) a healthy individual and (B) SARS-recovered individual (SARS subject 1) were expanded in vitro using a mixture of SARS-CoV peptides, followed by IFNγ ELISpot assay using SARS peptide matrix pools of the structural (top panels) and accessory proteins (lower panels). Each bar represents the IFNγ-producing response to an individual peptide matrix pool (numeric or alphabetic) in SFU per 5 × 10⁴ cells. The threshold for a positive response was set as two times above the mean SFU of unstimulated cells (Neg), as indicated by the dotted line in the right panels. Cells stimulated with PMA/ionomycin were included as positive control (Pos).