In-Depth Analysis of the Antibody Response of Individuals Exposed to Primary Dengue Virus Infection

Abstract

Humans who experience a primary dengue virus (DENV) infection develop antibodies that preferentially neutralize the homologous serotype responsible for infection. Affected individuals also generate cross-reactive antibodies against heterologous DENV serotypes, which are non-neutralizing. Dengue cross-reactive, non-neutralizing antibodies can enhance infection of Fc receptor bearing cells and, potentially, exacerbate disease. The actual binding sites of human antibody on the DENV particle are not well defined. We characterized the specificity and neutralization potency of polyclonal serum antibodies and memory B-cell derived monoclonal antibodies (hMAbs) from 2 individuals exposed to primary DENV infections. Most DENV-specific hMAbs were serotype cross-reactive and weakly neutralizing. Moreover, many hMAbs bound to the viral pre-membrane protein and other sites on the virus that were not preserved when the viral envelope protein was produced as a soluble, recombinant antigen (rE protein). Nonetheless, by modifying the screening procedure to detect rare antibodies that bound to rE, we were able to isolate and map human antibodies that strongly neutralized the homologous serotype of DENV. Our MAbs results indicate that, in these two individuals exposed to primary DENV infections, a small fraction of the total antibody response was responsible for virus neutralization.

Plasmablasts Generated during Repeated Dengue Infection Are Virus Glycoprotein–Specific and Bind to Multiple Virus Serotypes

“…This is in contrast to the previously reported MBC repertoire in dengue patients in which $50% mAbs bind to NS1, NS3, prM, or capsid (13)(14)(15). All Abs that bound to infected BHK-21 cells in histology also bound to virus particles in ELISA (Supplemental Table I).…”

“…In contrast to the memory B response, which is reportedly dominated by prM-and nonstructural protein-specific cells (6,(13)(14)(15), PBs preferentially bound to the E protein. This, in turn, implies that mature virus particles are the activating Ag that triggers B cells early during infection.…”

“…Previous reports described the specificity of MBCs isolated several weeks after acute infection with a known dengue serotype, followed by clone immortalization using EBV, screening of the secreted Abs, and cloning of Ab genes (13)(14)(15)(16). Most Abs isolated in this way were found to react with conserved epitopes in the prM and E domain of the virus or with nonstructural proteins and, therefore, were largely serotype cross-reactive.…”

Deconstructing the Antiviral Neutralizing-Antibody Response: Implications for Vaccine Development and Immunity

“…Neutralizing antibodies have been mapped to all three E protein domains and, in many instances, bind epitopes composed of residues from multiple domains (50)(51)(52)(53)(54)(55)(56)(57)(58)(59)(60)(61). Antibodies that recognize prM have also been identified, but they have limited neutralization potential (53,(62)(63)(64). The E proteins orchestrate the entry of flaviviruses into target cells, which occurs through receptor-mediated endocytosis, followed by pH-dependent fusion that typically occurs in late endosomes, although the relatively high pH threshold of ϳ6.6 suggests that fusion may already occur in early endosomes (65)(66)(67)(68).…”

Single-Cell Analysis of B Cell/Antibody Cross-Reactivity Using a Novel Multicolor FluoroSpot Assay

“…Infection with one DENV serotype confers protection from disease upon reinfection with the same serotype, but the immune response can contribute to either protection or increased disease severity upon infection with other serotypes (2). After a primary DENV infection, although crossreactive Abs predominate, neutralizing Abs are mostly type specific (3). In secondary DENV infections, type-specific Abs derived from primary memory B cells (MBCs) are maintained, but crossreactive Abs are induced at higher titers and can be strongly neutralizing (4)(5)(6)(7).…”