B Cell Responses during Secondary Dengue Virus Infection Are Dominated by Highly Cross-Reactive, Memory-Derived Plasmablasts

Abstract

Dengue virus (DENV) infection results in the production of both type-specific and cross-neutralizing antibodies. While immunity to the infecting serotype is long-lived, heterotypic immunity wanes a few months after infection. Epidemiological studies link secondary heterotypic infections with more severe symptoms, and cross-reactive, poorly neutralizing antibodies have been implicated in this increased disease severity. To understand the cellular and functional properties of the acute dengue virus B cell response and its role in protection and immunopathology, we characterized the plasmablast response in four secondary DENV type 2 (DENV2) patients. Dengue plasmablasts had high degrees of somatic hypermutation, with a clear preference for replacement mutations. Clonal expansions were also present in each donor, strongly supporting a memory origin for these acutely induced cells. We generated 53 monoclonal antibodies (MAbs) from sorted patient plasmablasts and found that DENV-reactive MAbs were largely envelope specific and cross neutralizing. Many more MAbs neutralized DENV than reacted to envelope protein, emphasizing the significance of virion-dependent B cell epitopes and the limitations of envelope protein-based antibody screening. A majority of DENV-reactive MAbs, irrespective of neutralization potency, enhanced infection by antibody-dependent enhancement (ADE). Interestingly, even though DENV2 was the infecting serotype in all four patients, several MAbs from two patients neutralized DENV1 more potently than DENV2. Further, half of all type-specific neutralizing MAbs were also DENV1 biased in binding. Taken together, these findings are reminiscent of original antigenic sin (OAS), given that the patients had prior dengue virus exposures. These data describe the ongoing B cell response in secondary patients and may further our understanding of the impact of antibodies in dengue virus pathogenesis. Dengue viruses (DENV) cause an estimated 390 million infections worldwide every year (1). With as many as 500,000 cases of severe dengue-related hospitalizations per year, dengue has emerged as one of the most critical arboviral diseases in the world today (2). There are four serotypes of dengue viruses (DENV1 to -4), and each can cause acute infection with a wide spectrum of symptoms (3). Clinical disease can range from self-limiting, mild febrile illness to dengue hemorrhagic fever (DHF) and the fatal dengue shock syndrome (DSS) (3-5). Individuals infected with dengue virus generate serum antibody titers that provide longterm protection against future homotypic infections (6). However, in cases of heterotypic infection, several seroepidemiological studies suggest that prior DENV exposure and preexisting antibody may be risk factors for severe disease (7-11). Furthermore, severe DENV infections typically evolve into DHF/DSS 3 to 7 days after fever onset (3), a time associated with a decline in viremia but a rise in serum antibody levels (12, 13). Consequently, in addition to its role in viral clearance, the...

Human antibody responses after dengue virus infection are highly cross-reactive to Zika virus

“…Therefore, even though a large number of dengue patient mAbs were able to bind viral epitopes, the capacity to cross-neutralize ZIKV was restricted to a select few. Additionally, a majority of these DENV-reactive mAbs were previously shown to neutralize more than one DENV serotype (Table S2) (13). Hence, for a large proportion of our mAb panel, the ability to cross-neutralize the virus did not extend beyond the DENV species to ZIKV.…”

“…4 A and B). At least 23 of the 26 ZIKV cross-reactive mAbs were E proteinspecific, as they were previously shown to bind recombinant DENV E protein (13). Although cross-reactive binding was abundant and all 26 ZIKV-reactive mAbs neutralized DENV2, less than a third neutralized ZIKV in vitro.…”

“…5C). These data demonstrate that ZIKV-reactive antibodies can potentiate The FRNT50 titers of flavivirus-naïve (n = 2) sera and acute (n = 9) and convalescent (n = 5) dengue sera were determined by FRNT assay as previously described (13). The FRNT assay for each sample was repeated in two or more independent experiments.…”

“…To dissect the cross-reactivity between DENV infection-induced antibodies and ZIKV, we characterized the binding and neutralization activity of a panel of plasmablast-derived mAbs against ZIKV. These mAbs were generated from in vivo-activated, single cell-sorted plasmablasts isolated during ongoing infection from four DENV2 patients and were previously shown to be DENV-reactive either in binding or in both binding and neutralization (13). Of the 47 mAbs tested, 22 bound with high affinity to ZIKV lysate (Fig.…”

“…The DENV envelope (E) protein, considered a major imunodominant target for antibody responses in dengue patients (13)(14)(15), bears greater than 50% homology to ZIKV E protein (16). In addition to complicating the serology-based diagnosis of ZIKV infection, this raises an interesting question about the biological implications of the cross-reactivity on protection, virulence, and immunopathology of ZIKV infections.…”