FIG 2.

(A) Schematic representation of the immunization procedure: five groups, each (n = 6) of 4-week-old mice, received sE-WT, sE-cvD, VLP-WT, VLP-cvD, or PBS mixed with alum-MPLA adjuvant as shown. Following two boosts at weeks 2 and 3, test bleeds were collected at week 4 for analyses. Anti-E antibody titers of sera collected from animals immunized with sE (B) or VLP (C) proteins. Antibody titers were determined using ELISA plates coated with mono-biotinylated monomeric E and dimeric E. Ctrl, pooled sera from PBS control group. The titer was defined as the maximum dilution that gives a value higher than three-times the value given by the preimmune sera. The control sera were negative at the lowest dilution (1:900), and their titer was calculated as one-third of that dilution (300). Statistical analysis was performed using a 2-sided analysis of variance (ANOVA), 95% confidence level, with Tukey’s pairwise comparison at 95% confidence (Minitab software).