Figure 2. Transgene product–specific CD8⁺ T cells fail to expand in response to a booster immunization.

(A) BALB/c mice were primed i.m. with 10¹¹ gc AAV2/7gag, and then 1 month later boosted i.m. with 10¹⁰ vp AdC68gag. Control mice were immunized with only the rAAV vaccine or only the AdC68 vaccine. (B and C) At 10 days (B) and 2 months (C) after the AdC68 immunization, splenocytes were stained with an antibody to CD8 and a gag-specific tet. Splenocytes were also stimulated with the AMQMLKETI peptide and analyzed by ICS for frequencies of gag-specific IFN-γ– and TNF-α–producing CD8⁺ T cells. (D and E) The order of immunizations was switched (D), and gag-tet–specific CD8⁺ T cell frequencies were determined by flow cytometry (E). Background frequencies (less than 0.1%) were subtracted prior to plotting. Frequencies shown are representative of at least 3 independent experiments. Error bars represent SD for 5 mice per group.