FIG 7.

Vaccination with Ad26 vectors induced only transient activation of peripheral blood but not foreskin CD4⁺ T cells. CD4⁺ T cell expression of CD69, CCR5, and HLA-DR in paired peripheral blood (A) and foreskin (B) specimens were evaluated at baseline (sham-immunized uninfected animals, n = 3), 2 days (n = 3), and 14 days (n = 3) after immunization with Ad26 vectors expressing SIV Gag/Pol/Env immunogens by using multiparameter flow cytometry. The magnitudes of IFN-γ-positive SIV Gag-specific and Ad26 vector-specific CD4⁺ (C) and CD8⁺ T cells (D) were quantified in peripheral blood and foreskin lymphocytes via ICS after stimulation with a pool of SIVmac239 Gag peptides (Gag), Ad26 hexon peptides (hexon), or empty Ad26 vectors (Ad26). Immunohistochemically stained foreskin tissue sections were evaluated for CD3, CD4, HLA-DR, and Langerin expression using the objective scoring criteria (Table 1) as detailed in Materials and Methods. Mean objective scores and representative IHC slides are presented for the animals at baseline (E), 2 days postvaccination (F), and 14 days postvaccination (G). BL, baseline; D2, day 2 postvaccination; D14, day 14 postvaccination; IEL, intraepithelial lymphocytes; LP, lamina propria. Error bars represent the SEM.