<p>Pooled immune sera from a DENV1 or DENV2 vaccine study were tested for their capacity to neutralize DENV1 and DENV2 RVPs. Sera pooled from multiple vaccinees (two and three for DENV1 and DENV2, respectively) were used in neutralization experiments by incubating RVPs with serial dilutions of immune sera for one hour at room temperature, before addition to Raji-DCSIGNR cells. After incubation at 37°C for two days, infection was measured using flow cytometry. Dose response curves for (<b>A</b>) DENV1 sera and (<b>C</b>) DENV2 sera are expressed relative to the infectivity of the RVPs in the absence of serum. The concentration of sera indicated on the x-axis is expressed as Log<sub>10</sub> (dilution factor of serum). Error bars represent the standard error of duplicate infections. Dose response curves shown in (<b>A</b>) and (<b>C</b>) are representative of 11 and nine independent experiments, respectively, performed using at least three independent RVP preparations. Neutralization titer (NT50) values were determined by nonlinear regression analysis using Prism software (GraphPad), and are summarized for (<b>B</b>) DENV1 sera and (<b>D</b>) DENV2 sera. Error bars represent standard error of the mean. ***p<0.0001.</p
