Dengue antibody-positive human serum samples from children and adults were obtained from patients with dengue and from persons who had participated in clinical trials of the Sanofi Pasteur recombinant CYD tetravalent dengue vaccine candidate. Yellow fever (YF)– and Japanese encephalitis (JE)–antibody positive human serum samples were obtained from healthy adult donors who received vaccines against YF virus (YF-VAX®) or JE virus (JE-VAX), respectively. Dengue antibody-negative human serum samples were obtained from healthy adult donors from non-endemic dengue areas.19 (link) Sample identifiers were removed and new sample identification numbers were issued. Samples were heat inactivated for 30 minutes at 56°C before use. Quality control samples were used in each assay run and demonstrated to be suitable for their intended purpose by consistently performing within the previously established neutralization titer limits, and served to monitor assay performance.