Figure 2.

Anti-EDIII antibody responses in mice immunized with pscDEC-EDIII and pscISO-EDIII. (A) Immunization regimen. Groups of BALB/c mice were immunized i.m. with the plasmids followed by electroporation. Three doses were given in 2-weeks intervals. (B) Total anti-EDIII IgG antibody titers and (C) IgG subclasses, 14 days after the administration of the third vaccine dose (n = 24; pscDEC-EDIII and pscISO-EDIII and n = 12; Saline, from three independent experiments). ELISAs were performed using recombinant EDIII as antigen and developed using a goat anti-mouse total or subclass specific IgG-HRP antibodies. Graphs show the antibody titers in normalized log10 scale. (D) Avidity of the anti-EDIII antibodies. Fixed dilutions of the pooled group samples were incubated with 7 M urea or PBS. The avidity index was calculated by the sample's OD₄₉₀ × 100 in 7M urea divided by the OD₄₉₀ in PBS. Symbols represent individual mice, columns, and bars represent the mean and SD for each group. Data were analyzed by a one-way ANOVA followed by the post-test HSD Tukey (B) or by unpaired t-test (D). P-value indicators **** refer to p < 0.0001. (E) Recognition of the DENV2 virus by the sera from mice immunized with pscDEC-EDIII and pscISO-EDIII. VERO cells were infected with DENV2 NGC strain or mock (medium). Cells were fixed with methanol and incubated with the sera from mice immunized with either scFv. The virus/sera and nuclei were labeled with the anti-mouse IgG-Alexa488 (green) and DAPI (blue), respectively. The 4G2 mAb was used as a control. Results shown are representative of two independent experiments. Scale bar, 10 μm.