FIG. 3.

Specific immune response of normal BALB/c mice induced by constructed plasmids and controls. (A) Anti-HB antibody response. Groups of mice were immunized with phosphate-buffered saline (PBS), pcDNA3, pcDNA-IL-21, pcDNA-S2S, pcDNA-IL-21+pcDNA-S2S, or pcDNA-IL-21/S2S, respectively. Anti-HB antibodies were determined by ELISA at different time points after immunization. ^###p<0.0001 compared with control groups. (B) Specific CD8+ T-cell responses were elicited following immunization. Sixteen weeks after first immunization, splenocytes were harvested and analyzed using an IFN-γ assay. The number of cells responding to stimulation with HBV S-peptides was represented as quantification of the number of spot-forming cells (SFC) per 10⁶ splenocytes. ^###p<0.0001 compared with PBS and pcDNA3 immunized groups. However, no significant differences were found among the three groups with MS vaccination. (C) Splenocyte proliferation in response to HBsAg. Splenocytes were stimulated with HBsAg (10 μg/mL) for 4 days, and cellular proliferation was calculated using a Cell Counting Kit-8 (CCK-8). (D), (E), and (F) Cytokine profiles of proliferating T-cells. The splenocytes were stimulated with HBsAg (10 μg/mL). The supernatants of cells were collected, and the concentrations of IFN-γ (D), IL-4 (E), and IL-17 (F) were detected by ELISA. ^###p<0.0001 compared with PBS and pcDNA3 immunized groups. The data were presented as mean±standard deviation.