FIG. 6.

Quantification of SIV Gag peptide-specific IFN-γ-producing CD8⁺ T cells in mice receiving prime and boost immunizations. Three mice per group were intranasally immunized with rFlu/SIVgag no. 3 (5 × 10² PFU), rFlu/SIVgag no. 4 (5 × 10² PFU), and rNDV/SIVgag (5 × 10⁷ PFU) as indicated. The spleen cells (A) and lymphocytes derived from cervical and mediastinal lymph nodes (B) were obtained 5 or 30 days after boosting. CD8⁺ T cells were selected and incubated with specific Gag peptide-pulsed P815 cells in an ELISPOT assay. Gag peptides 3 and 4 were used for stimulation of CD8⁺ T cells derived from rFlu/SIVgag no. 3 and rFlu/SIVgag no. 4 virus-immunized animals, respectively. As controls, CD8⁺ cells derived from spleen and lymph nodes of mice inoculated with PBS were used. The numbers of IFN-γ-secreting cells relative to the Gag peptides per million cells are represented.