Comparison of OVA-specific CD8+ T cell responses induced by pcDNA3-OVA delivered by different methods of administration. 5 to 8 weeks old C57BL/6 mice (5 per group) were vaccinated with HPV-16/OVA pseudovirions containing pcDNA3-OVA (50 ng) subcutaneously (s.c.), or pcDNA3-OVA either intramuscularly (IM) by electroporation (EP) (2 ug or 50 ng) or intradermally by gene gun delivery (2 ug or 50 ng). These vaccinated mice were boosted once after 7 days with the same dose and regimen. Splenocytes were collected one week after last vaccination, and stimulated with OVA MHC class I peptide SIINFEKL (1 ug/ml) in the presence of GolgiPlug. The OVA-specific CD8+ T cells were then analyzed by staining surface CD8 and intracellular IFN-γ. A. Representative flow cytometry data. B. Graphical representation of the number of OVA-specific CD8+ T cells per 3 × 105 splenocytes. Data expressed as means ± standard deviations (SD) are representative of at least two different experiments.