Fig. 2.

Vaccination induces OVA-specific IFN-γ-secreting spleen cells or CD8⁺ T cells in B6 mice. a Schematic of the experimental design of mouse immunization. Six-week-old B6 mice were vaccinated with FrC-OVA-pVAX1-GAG-MCS, wtBV, rBV or PBS on days 0 and 21 with the same vaccine via intramuscular injection. On day 35, the mice were sacrificed, and their spleens were isolated. b The IFN-γ contents in the supernatants of spleen cells from immunized mice were determined using IFN-γ ELISPOT analysis. Spleen cells were recovered and cultured for 24 h in the presence of OVA or HIV-1 Gag proteins. As a control, unstimulated spleen cells were cultured. c Intracellular staining of IFN-γ in splenocytes immunized with FrC-OVA-pVAX1-GAG-MCS, wtBV, rBV or PBS as indicated above. The spleen cells were incubated with the OVA peptide and brefeldin A for 4 h. The intracellular production of IFN-γ in the population of CD8⁺ T cells was then analyzed by flow cytometry. d Percentage of IFN-γ in CD8⁺ T cells. The results are representative of three independent experiments with six mice per group, and the error bars indicate the standard deviations of the mean values. ^*P < 0.05 (Student’s t-test)