Figure 3. Neutralizing antibody titers in mice immunized with vaccine candidates.

Groups of BALB/c mice (n = 5) were immunized subcutaneously with 10 µg D2ED III or LD2ED III two times at a two-week interval. Live dengue-2 virus (1×10⁷ FFU) was injected intraperitoneally on the same schedule. Sera were collected from mice at the indicated time points after the first immunization. The dengue-2 virus neutralizing capacity was determined by FRNT. The neutralizing antibody titer was calculated as the reciprocal of the highest dilution that resulted in a 50% reduction in FFU compared to control samples containing the virus alone. One of two representative experiments is shown. Statistical significance was determined by the ANOVA Bonferroni post test. ^* p<0.05; ^** p<0.01; ^*** p<0.001.