Vaccine-induced HIV Gag-specific immune response. (A) Bulk splenocytes were assessed for T cell immunity 1 week after prime and 1 week after boost. Splenocytes were restimulated for 6 h either with unreactive peptides (p17 pool 1) or with an HIV Gagp41 peptide mix, and IFN-γ, TNF-α, and IL-2 production was evaluated by intracellular cytokine staining in CD3+ CD4+ T cells and CD3+ CD8+ T cells. Arrows indicate CD8+ T cells. (B and C) Cytokine profile of CD3+ CD4+ T cell (B) and CD3+ CD8+ T cell (C) responses in vaccinated mice 1 week after prime and 1 week after boost. G, IFN-γ-expressing cells; T, TNF-α-expressing cells; L, IL-2-expressing cells. (D) Accumulation of Gag-specific CD8+ T cells in the spleen (left) and in the lungs (right) 1 week after prime and 1 week after boost. HIV Gag-specific T cell responses in the spleen and lungs of vaccinated CxB6 F1 mice were examined by using HIV Gag tetramer staining of total CD8+ CD3+ cells. Data are representative of 3 different experiments; data for 2 mice were pooled in each experiment.