Epitopes recognized by neutralizing antibodies have been identified in all three domains of the E protein [42] [43] [44] . To find out more about the epitopes of these neutralizing antibodies, we used phage display [29, 45] to identify the neutralizing epitopes. After three rounds of phage display biopanning, the phage titers were increased to 85-fold (DB32-6) and 331-fold (DB25-2) compared to the phage display biopanning results from the first round ( Figure 3A ). Individual phage clones from the third round of biopanning were randomly selected. ELISA was performed to determine whether the mAbs could specifically recognize selected phage clones. Of 20 selected phage clones, 17 and 18 clones had significant enhancement of binding activity to DB32-6 and DB25-2, respectively ( Figure 3B ). The selected phage clones PC32-6 and PC25-14 were specific and dose dependently bound to DB32-6 and DB25-2, respectively. They did not react with control NMIgG ( Figure 3C) .