FIG 7.

Immune responses are maintained at memory time points following intramuscular or intradermal PEPCK DNA vaccination. (A) Immunization schedule for PEPCK DNA vaccination. C57BL/6 mice were immunized twice, 2 weeks apart (n = 4 to 5 per group), either intramuscularly or intradermally. Spleens were harvested 45 days after the final vaccination for analysis of antigen-specific CD4⁺ T cell responses in the memory phase. (B) The frequency of PEPCK-specific IFN-γ responses (spot-forming units per million splenocytes) induced after vaccination was determined by an IFN-γ ELISpot assay in response to pooled PEPCK peptides. (C) Fold contraction of IFN-γ responses at 10 versus 45 days after the final vaccination. (D) PEPCK-specific CD4⁺ T cell responses to each consensus plasmid determined by intracellular cytokine staining after peptide stimulation. (E) PEPCK-specific responses to each plasmid at the site of vaccination determined by intracellular cytokine staining after peptide stimulation.