Neutralizing antibody curves. ZIKV neutralizing antibody titers were measured on days 0, 14, and 28. (A) The percent viral inhibitions corresponding to that log10 reciprocal serum dilution are plotted and fit with a nonlinear regression line in order to estimate the EC50 and EC90 values. (B) The log10 serum dilutions corresponding to EC50 nAb titers are plotted for days 0, 14, and 28. Increases in titers were measured by a one-way paired t test. Significance is indicated (**, P < 0.005).