Functional Transplant of a Dengue Virus Serotype 3 (DENV3)-Specific Human Monoclonal Antibody Epitope into DENV1

Abstract

The four dengue virus (DENV) serotypes, DENV1 through 4, are endemic throughout tropical and subtropical regions of the world. While first infection confers long-term protective immunity against viruses of the infecting serotype, a second infection with virus of a different serotype carries a greater risk of severe dengue disease, including dengue hemorrhagic fever and dengue shock syndrome. Recent studies demonstrate that humans exposed to DENV infections develop neutralizing antibodies that bind to quaternary epitopes formed by the viral envelope (E) protein dimers or higher-order assemblies required for the formation of the icosahedral viral envelope. Here we show that the quaternary epitope target of the human DENV3-specific neutralizing monoclonal antibody (MAb) 5J7 can be partially transplanted into a DENV1 strain by changing the core residues of the epitope contained within a single monomeric E molecule. MAb 5J7 neutralized the recombinant DENV1/3 strain in cell culture and was protective in a mouse model of infection with the DENV1/3 strain. However, the 5J7 epitope was only partially recreated by transplantation of the core residues because MAb 5J7 bound and neutralized wild-type (WT) DENV3 better than the DENV1/3 recombinant. Our studies demonstrate that it is possible to transplant a large number of discontinuous residues between DENV serotypes and partially recreate a complex antibody epitope, while retaining virus viability. Further refinement of this approach may lead to new tools for measuring epitopespecific antibody responses and new vaccine platforms. IMPORTANCEDengue virus is the most important mosquito-borne pathogen of humans worldwide, with approximately one-half the world's population living in regions where dengue is endemic. Dengue immunity following infection is robust and thought to be conferred by antibodies raised against the infecting virus. However, the specific viral components that these antibodies recognize and how they neutralize the virus have been incompletely described. Here we map a region on dengue virus serotype 3 recognized by the human neutralizing antibody 5J7 and then test the functional significance of this region by transplanting it into a serotype 1 virus. Our studies demonstrate a region on dengue virus necessary for 5J7 binding and neutralization. Our work also demonstrates the technical feasibility of engineering dengue viruses to display targets of protective antibodies. This technology can be used to develop new dengue vaccines and diagnostic assays.T he four dengue virus serotypes (DENV1 to DENV4), transmitted by Aedes species mosquitoes, are endemic throughout tropical and subtropical regions of the world (1). Primary infection with virus of one serotype confers long-term immunity against viruses of that serotype, but subsequent infection with virus of a different serotype results in an increased risk of potentially fatal severe dengue disease, including dengue hemorrhagic fever and dengue shock syndrome (2-4). This risk has been attributed, at least...

Protective Capacity of the Human Anamnestic Antibody Response during Acute Dengue Virus Infection

“…The binding of these antibodies was not decreased by residues identified as epitopes for the group A, B, or C antibodies. We note in particular that binding of the quaternary antibody 5J7 (27) lies on the E protein surface at the DI-DII interface close to the mutations identified on the underside of the E protein for group C antibody 7E-H1L1. However, binding by 5J7 was unaffected by any of these mutations on the underside, further suggesting that the epitope residues identified here for group A, B, C, and D antibodies do not perturb the global structure of the E protein.…”

Mapping the Human Memory B Cell and Serum Neutralizing Antibody Responses to Dengue Virus Serotype 4 Infection and Vaccination

“…Human DENV1, DENV2, and DENV3 type-specific neutralizing antibodies often bind to quaternary structure epitopes centered on the EDI/II hinge (17-19, 21, 38) and/or the EDIII region (2,20,21,39,40). Recently, we demonstrated that it is possible to recover recombinant chimeric DENVs displaying E protein domains or epitopes from viruses of two different serotypes (38,39). We used a rDENV4 strain with a mutated EDI/II hinge region and EDII region (rDENV4/3) to map the binding sites of hMAbs D4-126 and D4-131 ( Fig.…”

Dengue: knowledge gaps, unmet needs, and research priorities

“…75,92–95 These antibodies bind multiple sites on the E protein, including regions of EDIII, the fusion loop, and the hinge of EDI/II. 93 New tools are becoming available to dissect the repertoire of polyclonal sera, using depletion methods and epitope-transplanted recombinant viruses; 49,96,97 applying these to better understand the antibody response and potential immune correlates in DENV natural infections and vaccines is an area of active research.…”

“…144 Novel approaches being explored include “scaffolding” complex epitopes, such as the cross-neutralizing EDE epitope; bivalent vaccines that present two potent neutralizing type-specific epitopes simultaneously; and recombinant viruses on which epitopes recognized by enhancing antibodies are “masked”. 97,145,146 …”