FIG. 4.

Adoptive transfer of splenocytes or serum from mice with low levels of anti-Ad5 immunity. A total of 5 × 10⁷ splenocytes or 500 μl of serum from donor mice preimmunized with one injection of 10¹⁰ vp of rAd5-Empty was adoptively transferred to groups of recipient mice (four mice per group) prior to immunization of the recipient mice with 10⁸ vp of rAd5-Env. A group of mice with active anti-Ad5 immunity was included as a control. Vaccine-elicited immune responses were assessed by D^d/P18 tetramer binding to CD8⁺ T lymphocytes (A), Env peptide pool and P18 epitope peptide-specific IFN-γ ELISPOT assays (B), and Env-specific ELISAs (C).