Figure 5
Analysis of T cell responses elicited by the bivalent antigen. Splenocytes were obtained from mock-immunized (open bars) and test-immunized (gray, black and hatched bars) animals, 7 weeks after the final immunization and placed in culture. They were either mock-stimulated (open and gray bars) or stimulated in vitro, either with DEN-2 (black bars) or DEN-4 (hatched bars) for 96 hours for performing the T cell assays. Tritiated [3H] thymidine uptake was determined in a scintillation counter (A). Aliquots of the culture supernatant withdrawn at the indicated time points were assayed for the presence of IFN-γ (B) and IL-4 (C) by solid phase ELISA. Data depicted represent the mean value of three separate determinations (the error bars represent SD). In panel A, two dosage levels of virus were used for in vitro stimulation [L, low (0.015 PFU/cell); and H, high (0.03 PFU/cell); N, no antigen]. Data in panels B and C were generated using splenocytes stimulated with the high dose.