FIG 2.

The presence of adenovirus-derived epitopes abrogates the induction of GagL_85–93-specific CD8⁺ T cell responses. (A) CB6F1 mice were immunized once with DNA plasmids encoding strings of epitope-comprising sequences of F-MuLV leader-Gag, Ad5 DNA-binding protein (DBP), and Ad5 hexon. Two different constructs were employed, comprising the native leader-Gag-derived sequence and the native or alanine-modified DBP and hexon-derived sequences; an OLLAS tag was fused to the C terminus for detection of the fusion peptide. (B) Mice were immunized by intramuscular injection of 30 μg DNA, followed by in vivo electroporation. The GagL_85–93-specific CD8⁺ T cell response was analyzed 2 weeks after immunization by MHC I tetramer staining. (C) Three weeks after immunization, mice were challenged with 5,000 SFFU FV, and the viral load in plasma was analyzed 10 days later. (D and E) Three weeks after FV challenge infection, the spleens were removed and weighed (D), and viral loads in spleen cells were determined (E). Data were acquired in three independent experiments, using four mice per group per experiment. Each dot indicates an individual mouse, lines indicate mean (B and D) or median (C and E) values, and dashed lines indicate the detection limits. Data were analyzed by Kruskal-Wallis one-way analysis of variance on ranks and Dunn's multiple-comparison procedure for statistical significance. * and #, statistically significant differences (P < 0.05) compared to unvaccinated mice and compared to mice immunized with the respective plasmid comprising the native Ad-derived epitopes, respectively.