The HCMV-encoded CD8⁺ T-cell epitopes CPS and FPT are exclusively recognized by HLA B*3508 individuals. (A) Healthy HCMV seropositive donors (shown as D1-D8) who expressed different HLA B35 subtypes were assessed for CPS- and FPT-specific T-cell responses using ELISPOT assays as described in “Methods.” The results are expressed as spot forming cells (SFC) per 10⁶ PBMC. (B) In vitro stimulation of T cells with CPS and FPT epitopes confirmed effector-memory responses exclusively in HLA B*3508 individuals. Polyclonal CTL cultures were generated from 2 HLA-B*3508⁺ and 3 HLA-B3501⁺ healthy HCMV-exposed individuals by stimulation with CPS or FPT peptide epitopes. CTLs were tested as effectors at a range of E:T ratios for recognition of autologous phytohemagglutinin (PHA) blast target cells pretreated with the peptide used to stimulate the CTLs or left untreated. The HLA-A/B types of the donors were as follows: donor 1: HLA A2, A2, B*3508, B57; donor 2: HLA A23, A32, B*3508, B49; donor 3: HLA A1, A3, B8, B*3501; donor 4: HLA A11, A32, B*3501, B44, and donor 5: HLA A11, A24, B*3501, B60.