, 2007). OD values were evaluated at 490 nm by a plate reader (Synergy HT, Bio-TEK). Data were expressed as the stimulation index, calculated

as the mean reading of triplicate wells stimulated with antigen divided by the mean reading of triplicate wells stimulated with medium. Intracellular cytokine staining was performed as previously described (Wang et al., 2008). Briefly, single T-cell suspension from each group at 1 × 106 cells/100 μL was stimulated in a 96-well plate with HBsAg (5 μg mL−1) for 6 h, and treated with monensin (2 μg mL−1, eBioscience, San Diego, CA) for the last 4 h. Cells were blocked with Fc-Block (BD Phamingen, San Diego) for 30 min. Cells

were fixed with 4% paraformaldehyde for 15 min before permeabilization with 0.1% saponin for 10 min. The cells Wnt pathway were stained with isotype controls, or double stained with anti-CD8-PE plus anti-IFN-γ-FITC, anti-CD4-PE and anti-IFN-γ-FITC, anti-CD4-PE plus anti-IL-2-FITC, or anti-CD4-FITC plus anti-IL-4-PE for 30 min. The cells were detected by a FACS Calibur and analysed using cellquest pro Software (BD Bioscience). The frequency of CD4+CD25+Foxp3+ Treg cells was tested with the mouse regulatory T-cell staining kit according the manufacturer’s instructions (eBioscience). An in vivo cytotoxicity assay was performed as described previously (Zou et al., 2010). Single suspension cells from check details naive BALB/c mice were split equally into two portions. One portion as the target cell was labeled with 5 μM CFSE carboxyfluorescein mafosfamide diacetate, succinimidyl ester (Fan-bo biochemiscals, Beijing,

China; CFSEhigh) after being pulsed with the CTL peptide S208-215 (50 μg mL−1) for 4 h. The other portion as a nontarget control and was labeled only with 0.5 μM CFSE (CFSElow). The two portions were mixed in a 1:1 ratio and injected into immunized mice at 2 × 107 total cells per mouse via the tail vein on day 7 after the second immunization. Splenocytes were isolated 4 h later and the CFSE-labeled cells were tested by a FACS Calibur analyser based on their different CFSE fluorescence intensities. Specific lysis was calculated according to: % specific lysis = [1 – (% specific peptide-loaded target cells/% control peptide-loaded target cells)] × 100%. Total RNA was extracted from splenocytes of immunized mice with Trizol reagent (Invitrogen, Carlsbad, CA) according to the manufacturer’s instructions. cDNA was synthesized using Ace reverse transcriptase (Toyobo Co. Ltd, Pudong, Shanghai) with Oligo (dT) 18 primers (the primers for PCR are listed in Table 1). PCR products were resolved on 1.5% agarose gels and visualized by ethidium bromide staining under UV light.