FIG 4.

Determination of anti-E or neutralizing antibody titers for sera from vaccinated animals. (A) Anti-E titers: ELISA plates coated with biotinylated dimeric E were incubated with serially diluted serum samples, and the bound antibodies detected as described in Materials and Methods. Antibody titers were determined as described in the legend for Fig. 2. (B) Neutralization of ZIKV infection: serially diluted samples of mouse sera were incubated with ZIKV for 1 h before infecting Vero cells. At 72 h postinfection, the intracellular levels of E were determined by capture sandwich ELISA, and the percentage infectivity relative to that of the virus alone was calculated. The results were plotted as MN₅₀ values, i.e., titers at which 50% neutralization was achieved. Statistical analysis was performed using 2-sided ANOVA, 95% confidence level, with Tukey’s pairwise comparison at 95% confidence (Minitab software). Data from three independent experiments were used.