Figure 3. Cellular responses and T cell activation.

SIV Gag-specific, IFN-γ-secreting cells were measured by ELISPOT assay (A) before the low-dose SIVsmE660 challenge phase, (B) during the low-dose challenge phase, or (C) after the low-dose phase but before the high dose rechallenge with SIVsmE660 and (D) T cell activation was measured by percentage of CD3⁺ Ki67⁺ cells.