We next tested the ability of the 16 antibodies generated from donor 033 to neutralize DENV. Five hMAbs including the two that did not bind to the virion lacked neutralizing activity ( Figure 2 ). The remaining antibodies ranged from weak to moderately neutralizing and had DENV3 50% neutralization titers that ranged from 0.09 to 1 mg/ml (Figure 2A ). The neutralizing antibodies had similar 50% neutralization titers against all 4 serotypes, which was consistent with their broad binding specificity (data not shown). In general, prM antibodies had neutralization curves that were shallow and did not reach 100% neutralization, indicating that a fraction of the virus population was resistant to antibody neutralization ( Figure 2B ). The single E reactive antibody (DV64.31) exhibited a steeper neutralization curve and neutralized 100% of virus at high concentrations ( Figure 2C ). In summary, the hMAbs generated from donor 033, who had experienced a primary DENV3 infection, were broadly cross-reactive, weakly neutralizing, and mainly directed to epitopes on prM. None of the hMAbs mimicked the functional properties of immune serum from donor 033 that displayed strong type-specific neutralization of DENV3 (Table S1 ). A complete summary of the functional profiles of all sixteen hMAbs from donor 033 is included as supplementary material (Table S2 ).