Comparison of the HA, NA, and NP peptide-pooling matrices and individual peptides in the SJL and B10.S mouse strains. HA (A), NA (B), and NP (C) peptide-pooling matrices were screened in EliSpot assays using CD4-enriched T cells obtained from previously infected SJL (white bars) and B10.S (black bars) mice, with each peptide in the pooling matrix at a final concentration of 10 μM. The pattern of positive and negative peptide pools was compared between the two mouse strains. Data are presented as the percentage of total spots, with error bars representing the standard error over at least two individual assays. Panel D shows a comparison of select I-As-restricted epitopes in an EliSpot assay using CD4-enriched T cells isolated from previously infected SJL (white bars) and B10.S (black bars) mouse strains in parallel. Data are presented as the average number of spots per 106 CD4-enriched T cells, with error bars representing the standard error over all assays performed.