An early commitment to expression of a particular TCRVβ chain on CD8+ T cells responding to attenuated Plasmodium berghei sporozoites is maintained following challenge with infectious sporozoites

Protection induced by irradiated Plasmodium berghei sporozoites (Pbγ-spz) in mice is linked to CD8+ T cells specific for exo-erythrocytic-stage Ags, and intrahepatic memory CD8+ T cells are associated with protracted protection. However, the Ag specificity of the protective CD8+ T cells remains largely unknown. In this study, we characterized the TCR Vβ usage by intrahepatic CD8+ T cells during γ-spz immunization and after the challenge with infectious Pb sporozoites. The repertoire of naïve (TN) and central memory (TCM) CD8+ T cells was diverse and conserved between individual mice, and did not change with immunization. In contrast, preferential usage of one or more TCR Vβ subset was observed in effector memory (TEM) CD8+ T cells after immunization. The expanded TCR Vβ varied between individual mice but Vβ4, 6, 7, 8.3, 9 and 11 were the most frequently expressed. In addition, there was a correlation in the TCR Vβ usage by γ-spz-induced CD8+ TEM in the liver and blood of individual mice. The expansion pattern of blood CD8+ TEM did not change with challenge and remained the same for 8 weeks thereafter. These results demonstrate that immunization with γ-spz skews the TCR Vβ repertoire of CD8+ TEM, and commitment to a particular TCR Vβ expression is maintained long-term.