Figure 4.

Vaccination with rAd leads to induction of tumor-reactive CTL activity against the E1-derived CTL epitopes. B6 mice were left nonimmunized, were immunized with rAd-1, harboring minigene 1, or were immunized with rAd-2, harboring minigene 2. Two weeks later, spleen cells of these animals were taken and restimulated with Ad5E1-transformed tumor cells to propagate E1A- and E1B-specific CTL. Lytic activity of bulk CTL cultures was tested 6 days later on Ad5E1 MEC, untransformed B6 MEC loaded with the Sendai-virus encoded control CTL epitope FAPGNYPAL, the E1A-encoded CTL epitope, the E1B-encoded CTL epitope, or the HPV16 E7-encoded CTL epitope. Mice immunized with rAd-1 recognize the E1A- and E1B-encoded CTL epitopes as well as tumor cells endogenously presenting these epitopes. Mice immunized with rAd-2 recognize the E1B epitope as well as tumor cells endogenously presenting this CTL epitope, whereas nonimmunized mice do not display reactivity against the target cells. Percent specific lysis at different effector to target cell ratios is shown.