FIG. 4.

TCR Vβ repertoire analysis of serovar Typhi-specific CD8⁺ T cells in volunteers immunized with the attenuated serovar Typhi strain Ty21a typhoid vaccine. PBMC from volunteers 1, 2, and 3 were analyzed ex vivo or after weekly restimulation with autologous serovar Typhi-infected targets for up to 3 weeks, and the percentage of 24 TCR Vβ specificities was determined by flow cytometry. Data are presented as the percentage of TCR Vβ⁺ cells in CD3⁺ CD4⁻ CD8⁺ gated populations. Only the percentages of TCR Vβ⁺ cells above the mean plus 3 SE of all Vβ specificities ex vivo postimmunization (dashed lines) were considered to be significant. The percentage of TCR Vβ 2 in volunteer 1 after three cycles of restimulation is not available because of technical difficulties.