FIG. 2.

IFN-γ responses following coimmunization of DNA expressing Nef with DNA expressing cytokine or hematopoietic factors. Mice were intramuscularly immunized with DNA without an insert (control) or plasmid expressing Nef alone (80 μg and 20 μg of pNGVL per mouse) or with Nef plus IL-2, IL-15, IL-12, GM-CSF, or FL (20 μg/mouse); FL and IL-2, IL-15, or IL-12 (10 μg of each cytokine/mouse), Nef, and FL on the first immunization and Nef and IL-2 or IL-12 on the second and third immunizations (2+3); or empty vector (pNGVL). Two weeks after the third immunization, spleens from immunized mice were restimulated in vitro with Nef protein in the form of a GST fusion-tagged protein at 5 (A) or 1 (B) μg/ml. IFN-γ secretion was assessed by ELISA in supernatants removed at 72 h. Responses are mean (plus standard deviation) concentrations, with the statistically insignificant background subtracted, for 5 to 16 mice per group. *, P < 0.05; **, P < 0.01; ***, P < 0.005 versus pNGVL-Nef-immunized mice at the same in vitro dose of Nef protein.