The inhibition of adenovirus vector expression by MVA was also confirmed through in vitro experiments. Furthermore, the suppression factor(s) included an undefined soluble protein, besides cytokines such as type I IFN. Two viral vectors were used in this study: One vector was an E1/3-deleted adenovirus vector expressing the secreted alkaline phosphatase SEAP gene (Ad-SEAP), HIVIIIB gp160 Env (Ad-HIV)
, the green fluorescent protein (Ad-GFP) or mCherry fluorescent protein (Ad-Cherry). Another vector was modified vaccinia virus Ankara expressing HIVBH2 gp160 Env and a report gene LacZ (MVA-HIV, a kind gift from Dr. Bernard Moss, National Institutes of Health, Rockville, MD) or the green fluorescent protein (MVA-GFP). The Ad vector was propagated in HEK293 cells and purified over Afatinib in vivo CsCl as described elsewhere . The total concentration of virions in each preparation was calculated by using the following formula: 1 OD260=1012 viral particle (vp)/ml1 OD260=1012 viral particle (vp)/ml The MVA virus was propagated in the BHK21 cell line and purified by one round of ultracentrifuge over 36% sucrose. The MVA virus was titrated Selleck Gefitinib in the BHK21 cell line to determine the number of plaque forming units (pfu). Eight-week-old BALB/c mice (H-2Dd) were purchased from
Japan SLC Inc. (Shizuoka, Japan). The mice were immunized with an intramuscular injection of 1010 vp of Ad-HIV and Ad-GFP, 107 pfu of MVA-HIV, or 105–7 pfu of MVA-GFP. All experiments were performed in accordance with the guidelines of the University
Animal Care and Use Committee of the Animal Research Center, Yokohama City University Graduate School of Medicine. The assay was performed as described previously . The H-2Dd/p18 tetramer (RGPGRAFVTI; synthesized by NIH Tetramer Core Facility, Atlanta, GA) labeled with phycoerythrin (PE) was used for the tetramer assay. Briefly, 100 μl of heparinized whole mouse blood was stained with 0.25 μg of fluorescein isothiocyanate (FITC-conjugated) anti-mouse CD8a antibody (clone 53-6.7; eBioscience, San Diego, CA), along with 0.05 μg of tetramer reagent at room temperature for 30 min. The cells were all then fixed with 100 μl of OptiLyse B-Lysing solution (Beckman Coulter, Marseille Cedex, France) at room temperature for 10 min. Erythrocytes were lysed by adding 1 ml of H2O and washed with phosphate-buffered saline (PBS). To detect antigen-specific memory T cells, the cells were co-stained with PE-p18 tetramer, FITC-anti CD8 antibody, 0.1 μg of phycoerythrin/cyanin7 (PE Cy7)-conjugated anti-mouse CD62L antibody (clone MEL-14; Biolegend, San Diego, CA), and 0.25 μg of Alexa Fluor 647-conjugated anti-mouse CD127 antibody (clone SB/199; AbD Serotec, Oxford, UK), similar to the tetramer assay described herein. The p18 tetramer+CD62L+CD127+CD8 T cells and p18 tetramer+CD62L−CD127+CD8 T cells were respectively defined as central memory (CM) CD8 T cells and effector memory (EM) CD8 T cells.