Fig. 1.

IFN-γ-producing cells after the primary and secondary sets of immunization. Samples were taken 2 weeks after each injection and assessed for an SIVgag antigen-specific response by ELISpot. (A–C) The number of cells able to secrete IFN-g after SIVgag in vitro stimulation of PBMCs isolated from naïve macaques (A) pCSIVgag (B), pCSIVgag, and pmacIL15 immunized macaques (C) is presented as SFC per 1 million PBMCs. (D) After the final immunization, we evaluated the contribution of the CD8 T cells to the observed population of cells from macaques secreting IFN-γ.