Figure 4

CD8+ T cell responses differentially recognized Nef epitopes in the 2 T/F viruses. The epitopes Nef68-76 (A) and Nef19-27 (C) varied between the major and minor T/F viruses. T cell responses were measured by ex vivo IFN-γ ELISpots with responses against the major T/F shown by blue squares and responses against the minor T/F shown as red diamonds. T cell responses to subsequently emerging escape variants are shown as triangles. To the right of these graphs, the changes in each epitope are shown over time. The EC₅₀ of the Nef68-76 T cell response targeting the major variant was lower than that of the response targeting the minor variant (B). dps = days post-screening (Fiebig I/II).