We evaluated the ability of mAbs to inhibit DENV-2 infection in BHK-21 cells using a plaque reduction neutralization test (PRNT). Ten mAbs had neutralizing activity with 50% PRNT (PRNT 50 ) concentrations ranging from 0.14 mg/ml to 33 mg/ml (Table 1) . DB32-6 was found to be a DENV-2 serotype-specific mAb against E-DIII ( Figures 1A, 1B and 1E) and was the most efficient at neutralizing DENV-2 infection at a PRNT 50 concentration of 0.14 mg/ml (Figure 2A ). In addition, it could completely inhibit the infection at a lower concentration of 1.2 mg/ml (Figure 2A) . The mAb DB25-2 was found to be a DENV-2 serotype-specific mAb against E-DIII ( Figures 1A, 1B Humanized mAb against Dengue Virus www.plosntds.org and 1E) and to neutralize DENV-2 at a PRNT 50 titer of 1.2 mg/ ml (Figure 2A) . These findings indicate that serotype-specific mAb DB32-6 against E-DIII was the most potent in neutralizing DENV infection. Some serotype-specific mAbs, such as DB2-3 and DB23-3 against E-DI-II and DB25-2 against E-DIII showed strong neutralizing activity. Many complex reactive mAbs showed moderate-to-poor neutralizing activity (Table 1) . mAbs prevent DENV-2-induced lethality in suckling mice and Stat1 2/2 mice Two different mouse models were used to assess whether DB32-6 could efficiently protect mice against DENV-2 challenge.