HTL responses are crucial for the development of CD8 + T responses, at least in the case of lipidated covalently or non-covalently linked HTL-CTL epitope constructs formulated in PBS. Several previous studies have illustrated a role for CD4 + responses for development of CD8 + CTL responses, both in humans and in experimental animals [30] [31] [32] [33] [34] [35] . The inclusion of PADRE, a synthetic peptide that binds promiscuously to variants of the Figure 6 New peptides tested with PBMCs from HLA-A03 seropositive and seronegative donors. Then Peripheral blood mononuclear cells from seropositive T. gondii donors were tested for response to these predicted HLA-A03 supertype restricted CD8 + T cell epitope individual peptides by using IFN-γ ELISpot assay. Peptides that induced significant IFN-γ spot formation compared to DMSO are denoted by an asterisk. *, P < 0.05. Figure 7 Addition of peptides to pool robustly protects HLA-A*1101 mice against Type II parasite challenge. HLA-A*1101 transgenic mice were immunized with PBS (controls) or peptide pool with PADRE and Pam 2 Cys in GLA-SE. Splenic T cells were isolated 10-14 days post immunization and exposed to each peptide in an ex vivo IFN-γ ELISpot assay (Figure 7a ). HLA-A*1101 transgenic mice immunized with peptide pool and adjuvants were protected compared with control mice inoculated with PBS when they were challenged with 10,000 Pru (Fluc)-T. gondii luciferase expressing parasites (Figure 7b ). Mice were immunized and in a subgroup immune function was studied at the same time as the challenge shown was performed. Differences between control and immunized mice were significant (p < 0.0064 using natural log transformed data and two-sample t test).