Figure 5

Enhancing activity assay for patient sera using the new assay system. Samples #19-20, #37-20 and #37-30 were obtained from Chinese subjects positive to DENV, with a sample from healthy people #NS as a negative control. Sera in various dilutions were mixed with Luc-DENV and incubated for 72 h, and luciferase activities were measured in lysed K562 cells to assay enhancing activities. Error bars indicate the standard deviations from two independent experiments.