Fig 1. HHV-6B peptide-specific polyclonal T cell lines and CD8 T cell clones.

(A) Peptide-specific T cells in PBMCs from four healthy HLA-B*08:01-positive donors (a-d) were detected in an IFN-γ ELISPOT assay. PBMCs were stimulated with pools of 146 octameric or 153 nonameric HHV-6B/HLA-B*08:01 candidate peptides, 29 Epstein-Barr virus peptides (positive control), or no peptides. Mean+SD of 3 replicates is shown. (B) T cell cultures from donor 1 were stimulated with the complete octamer or nonamer peptide pools for 42 or 56 days as indicated, and then tested in IFN-γ ELISA or ELISPOT assays for reactivity to non-overlapping peptide subpools. HLA-B*08:01-positive activated B cells (mini-LCLs) were used to present peptides. Mean+range of 2 replicates is shown. (C) CD8 T cell clones were screened for reactivity to HHV-6B peptide pools in IFN-γ ELISA, as shown in this example for 12 T cell clones. Autologous CD40-activated B cells were used to present peptides. (D) To identify each T cell clone's target within the peptide libraries, T cells were stimulated with "crossed" peptide subpools. One positive signal each for horizontal and vertical subpools identifies the target peptide, as shown here for one T cell clone, which turned out to be specific for the QTR peptide from U41.