Immune complexes were formed by mixing coupled beads and appropriately diluted plasma and incubating for 2 hours at 37C. == One-Sentence Summary: == Antibody Fc characteristics and effector functions correlate with protection from symptomatic DENV3 infection. More than 3.9 billion people worldwide are estimated to live in areas at risk for dengue virus (DENV) infection (1). Four serotypes (DENV14) are transmitted through the bite ofAedesmosquitoes, accounting for up to 100 million infections annually, with 50 million being symptomatic and up to 4 million requiring hospitalization (2). Symptomatic infections can present as classical dengue fever or the more severe dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) (3). Primary DENV infections generate serotype-specific neutralizing antibodies (nAbs) that confer long-term protection against homotypic infections and cross-reactive nAbs that can protect against heterotypic infections(4). However, non-protective cross-reactive antibodies can sensitize individuals to secondary heterotypic symptomatic infection and severe disease via antibody-dependent enhancement (ADE) by mediating infection of Fc receptor (FcR)-bearing myeloid cells (57). Further, high-affinity binding of anti-DENV afucosylated IgG1 antibodies to FcRIIIA has been associated with severe disease outcomes (810). As such, anti-DENV antibodies play roles in both protection and pathogenesis. Our limited understanding of the mechanisms and correlates of protection for dengue disease has hampered the development and assessment of vaccine candidates. Of note, the Sanofi Pasteur Dengvaxiaclinical trials showed that DENV vaccines can be protective in DENV-seropositive recipients but can increase the risk of hospitalization in DENV-seronegative recipients during a subsequent infection (11,12). Neutralization assays performed on samples from these trials found that the correlation of nAb titers with vaccine efficacy and protection from dengue disease varied by serostatus, DENV serotype, and type-specific versus cross-reactive antibodies(1316). Given the complex nature and technical challenges of nAb-based assays, additional immune correlates of protection need to be explored. Beyond antigen-specific properties, antibodies can contribute to protection using other mechanisms, including leveraging antiviral activities of the innate immune system through engagement of the antibody constant (Fc) region. Fc effector functions are critical antibody features for protection against disease caused by several viruses, including HIV, influenza virus, Ebola virus, and SARS-CoV-2 (1720). Although Fc-effector functions have been implicated in enhancing DENV disease (810), a role for antibody Fc-mediated mechanisms of protection remains largely unexplored for DENV. == Results == == Binding antibody titers are associated with protection from symptomatic DENV infection == We undertook an unbiased, comprehensive, systematic profiling of DENV-specific humoral immune responses to probe for correlates of protection against secondary DENV infection. Antibody-associated correlates of protection were determined Rabbit Polyclonal to FST in samples selected during resting state months or years after one or more previous DENV infection(s) but before a subsequent heterotypic secondary infection. We assessed a panel of antibody features in plasma samples from previously DENV-infected children (413 years old) prior to subsequent DENV3 infection from our long-standing cohort study in Managua, Nicaragua (21) (Fig. 1AandTable 1). The samples were classified into two groups: pre-inapparent attacks (children having a >4-fold upsurge in binding antibody titers in combined annual samples without reported dengue-related symptoms in the intervening yr, n=30) and Amonafide (AS1413) pre-symptomatic attacks (kids with laboratory-confirmed dengue instances, n=29). The annals of attacks was categorized as prior major or secondary disease and was established predicated on longitudinal evaluation of nAb titers, envelope domain III (EDIII) binding antibodies, epidemiological data, and real-time disease and RT-qPCR isolation of symptomatic attacks. For kids who signed up for the cohort research with pre-existing anti-DENV antibody titers (n=13), we evaluated their probable background of disease predicated on an EDIII Luminex assay, as anti-EDIII antibodies have already been connected with higher degrees of type-specific antibodies and may be helpful for identifying history infecting serotypes (Desk 1,desk Amonafide (AS1413) S1, anddata document S1). DENV1, DENV2 and/or DENV4 had been identified as the prior infecting serotype(s). Several samples were categorized as indeterminate because of high cross-reactivity, most likely associated with earlier secondary disease and high binding antibody titers. Furthermore, only two examples were connected with following serious disease (DHF), with the rest of the individuals showing with traditional dengue fever (data document Amonafide (AS1413) S1). Therefore, this sample arranged allowed us to research cross-reactive antibody reactions against a following heterotypic supplementary DENV3 disease to analyze immune system correlates connected with inapparent versus symptomatic disease. == Fig. 1. Fc and Biophysical effector features of anti-DENV polyclonal antibodies. == A) Pre- inapparent (blue).
