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In tropical and subtropical countries, dengue virus (DENV) infections have been increasing; however, we still lack effective therapy. In the present study, we aimed to engineer a bispecific antibody (subsequently named LUZ-8F2–6B1), based on monoclonal antibody 6B1, which has anti DENV-1, 2, and 3 activity, and 8F2, which has anti DENV-4 activity. LUZ-8F2–6B1 displayed potent neutralization activity against four serotypes of DENV by binding to the envelop protein. In vivo , we demonstrated that LUZ-8F2–6B1 could provide protection against infection by four serotypes of DENV in a mouse model. In addition, the deletion of nine amino acids in the Fc region (LUZ-8F2–6B1-9del) completely abolished the antibody-dependent enhancement observed at lower doses of the antibody. Thus, LUZ-8F2–6B1 is a promising, safe, and effective agent for the prophylaxis and treatment of DENV infection. • An engineered bispecific antibody LUZ-8F2-6B1 showed potent neutralization activity against all four serotypes of DENV. • In vivo, a mouse model showed that LUZ-8F2-6B1 provided protection against infection by all four serotypes of DENVs. • LUZ-8F2-6B1-9del completely abrogated antibody dependent enhancement, which occurs when using lower doses of the antibody. • LUZ-8F2-6B1 could be an effective and safe agent for the prophylaxis and therapy of DENV infection. [ABSTRACT FROM AUTHOR]

Dengue virus (DENV) is a prevalent mosquito-transmitted human pathogen, causing about 100 million cases of acute dengue fever and 21,000 deaths annually worldwide. Therapeutic neutralizing antibodies against dengue virus might be effective to treat severe dengue fever. Here, we showed that human monoclonal antibody (HMAb) 9C7 bound to all four intact serotypes of DENV but not to the recombinant envelope protein, suggesting HMAb 9C7 recognized a conformational epitope of the envelope protein. Taken together our results suggested that HMAb 9C7 neutralized all four serotypes of DENV in vitro and, for DENV-1, indicated activity at the pre- and post-attachment steps in the viral life cycle. HMAb 9C7 potently protected suckling mice from lethal challenge with all four serotypes of DENV. FcγRII-mediated uptake of immune complexes and antibody-dependent enhancement at low doses of the antibody were abolished by two Leu-to-Ala (9C7-LALA) mutations or deletion of nine amino acids (9C7-9del) in HMAb 9C7 Fc. Therefore, HMAb 9C7 represented a promising prophylactic and therapeutic agent against all four serotypes of DENV. • We generated and characterized a novel DENV-specific HMAb 9C7 recognized a conformational epitope of the envelope protein. • HMAb 9C7 potently neutralized all four serotypes DENV in vitro at the pre- and post-attachment steps in the viral life cycle. • HMAb 9C7 potently protected model mice from lethal challenge with all four serotypes of DENV. • FcγRII-mediated ADE were abolished by two Leu-to-Ala mutations or deletion of nine amino acids in HMAb 9C7 Fc. [ABSTRACT FROM AUTHOR]