Figure 6. Induction of anti-CEA T cell responses with the Ad5[E1−, E2b−]CEA vector is not diminished in mice with pre-existing anti-Ad immunity.
Mice were immunized with 0 (saline), 1, or 3 injections of an replicating adenovirus vector (Ad5[RC]) to induce differing levels of pre-existing anti-Ad5 immunity, reflected by the anti-adenovirus antibody titers shown in Fig. 5a and anti-Ad5 T cell responses in Fig. 5b. Subsequently, mice received 3 vaccinations with the Ad5[E1+]CEA, Ad5[E1−]CEA, or Ad5[E1−, E2b−]CEA vectors as indicated. The magnitude of anti-CEA T cell responses was measured by Interferon-gamma ELISPOT for the naïve (0 injections of Ad5[RC]) and Ad-pre-immune mice (1 or 3 injections of Ad5[RC]). SFC: spot forming cells. Error bars represent standard deviation. The data are representative of four experiments.