DYS-specific CD4⁺ T-cell clones recognize peptide derived from processed gB protein. (A) DYS-specific CD4⁺ T-cell clones were stimulated with HLA-DRB*0701–positive LCL pulsed with DYS peptide, irrelevant peptide, or CMV lysate, or following infection with MVA-gB, MVA-pSC11 (empty vector), or ultraviolet-irradiated MVA-gB. Antigen-specific responses were determined by IFN-γ ELISA and expressed as the percentage of maximal IFN-γ release from peptide-loaded targets. To confirm the HLA restriction of the DYS-specific T-cell response, autologous or allogeneic (HLA-DRB*0701–positive or HLA-DRB*0701–negative) LCL targets were pulsed with DYS peptide before incubation with DYS-specific T-cell clones. Recognition is expressed as the percentage of maximal IFN-γ release from DYS peptide–loaded autologous targets. (B) Functional avidity of DYS peptide–specific clones. LCLs were pulsed with variable concentrations of DYS peptide before incubation with DYS-specific T-cell clones. Results are expressed as the percentage of maximal IFN-γ release, and functional avidity was correlated with concentration of peptide required to produce 50% maximal response (broken line). Peptide titrations of six clones from 3 different donors are shown.