Fig. 6

Comparison of immune responses and protection induced by a combined Ad-based vaccine and the attenuated retrovirus F-MuLV-N. CB6F1 mice were either immunized with an Ad based vaccine, consisting of an immunization with 10⁹ vp each of Ad.TxnGagL and Ad.Gag_C1K, followed by an immunization three weeks later with 10⁹ vp Ad.pIXgp70, or mice were immunized with 10 000 FFU of the N-tropic F-MuLV-N. 6 weeks after the first immunization, mice were challenged with 5000 SFFU FV complex. The frequencies of GagL_85–93-specific CD8⁺ T cells (a) and Env_123–141-specific CD4⁺ T cells (b) were analyzed by MHC I and MHC II tetramer staining, respectively, five weeks after initialization of the immunizations (i.e. 2 weeks after Ad.pIXgp70 immunization); the binding antibody response was analyzed at the same time point (c). Neutralizing antibodies were quantified both five weeks after initialization of the immunizations (d, left) and 10 days after the FV challenge infection (d, right). The viral load in plasma was analyzed 10 days after FV challenge infection (e), the viral load in spleens was analyzed three weeks after the FV challenge infection (f). The data shown were acquired in three (b–d) to five independent experiments (a, e, f) using three to five mice per group per experiment. Each dot represents one mouse, lines indicate mean (a, b) or median (c–f) values, dashed lines indicate the limits of detection. Data were analyzed by Kruskall–Wallis One Way Analysis of Variance on Ranks and Dunn’s multiple comparison procedure (a, b, d–f) or by Mann–Whitney Rank Sum Test (c). Significant differences (P < 0.05) compared to unvaccinated mice are indicated by *, significant differences compared to mice vaccinated with the Ad-based vaccine are indicated by #. Sufficient statistical power was verified [SP = 0.99 (a), 0.88 (b), 1.0 (c), 0.99 (d left), 1.0 (d right), 0.99 (e), 0.99 (f)]