Seventeen mAbs with high reactivity against E protein of DENV-2 were generated after immunization of mice with DENV-2 strain 16681. We identified 17 mAbs belonging to the IgG isotype that reacted with DENV-2-infected cells but not with mock-infected cells using immunofluorescence assay (IFA) ( Figure  S1 ) and ELISA ( Figure 1A ). 4G2 was a pan-flavivirus mAb that could recognize the fusion loop of E-DI-II, and 3H5 (ATCC HB46) was a DENV-2 serotype-specific mAb that could recognize the lateral ridge of E-DIII [12, 17, 40] . Both 4G2 and 3H5 were used as positive controls (Figure 1 ). The specificities of the mAbs recognized as the four DENVs were further confirmed by ELISA and Western blotting (Figures 1A-1B and Table 1 ). Based on our Western blot analysis using a nonreducing condition, 14 of the mAbs recognized E protein (53 kDa) ( Figure 1B ). Three mAbs could not be identified by Western blotting. In order to identify the target proteins of these mAbs, we prepared BHK-21 cells transfected with plasmids expressing DENV-2 C, prM, prM-E, E, NS1, NS2A, NS2B, NS2B-3, NS3, NS4A, NS4B and NS5 ( Figure S2 ). Results indicated that three mAbs (DB21-6, DB22-4 and DB36-2) recognized E protein ( Figure 1C ). The identification and characterization of the 17 mAbs are summarized in Table 1 .