Beyond neutralization: A comprehensive framework for evaluating humoral immunity induced by a live-attenuated...

Dengue incidence is increasing worldwide. TAK-003, a live-attenuated tetravalent dengue vaccine, is licensed in several countries. Its safety, efficacy, and immunogenicity have been extensively studied and provided the roadmap for recommendations and implementation. Per WHO guidelines, the primary immunogenicity endpoint in dengue vaccine clinical trials is neutralizing antibody (NAb) titers. However, there is no established immunological correlate of protection, and dengue virus (DENV) elicits a broad range of antibody responses. This study assessed statistical and experimental methods to evaluate a wide range of antibody responses to TAK-003 as a framework for evaluating vaccine immunological signatures that may correlate with protection from dengue infection and/or disease.

Responses were assessed by the following immunoassays: microneutralization assay, DENV total binding IgG ELISA, anti-dengue complement antibody assay, anti-dengue non-structural protein 1 (NS1) IgG ELISA, and anti-dengue IgG avidity assay. Samples from TAK-003 vaccinated/placebo participants from several trials were tested. Results were compared for assay performance and the impact of baseline serostatus, serotype, and age on vaccine-elicited responses. Correlation analyses assessed relationships among variables. Principal component analyses (PCA) evaluated data complexity.

Vaccination elicited responses to all four DENV serotypes in each assay. The magnitude of vaccine-induced responses was higher in baseline seropositive participants, but vaccine effect was stronger in baseline seronegative participants. Baseline seronegative participants had comparable DENV total binding IgG concentrations, anti-dengue IgG avidity, and anti-dengue complement antibody titer responses across all serotypes. MNT₅₀ NAb and anti-dengue NS1 IgG responses varied by serotype. Modest to low correlations across parameters suggest that the different assays measure non-redundant vaccine-induced humoral immune responses. The major source of response variability was post-vaccination time, followed by serotype.

TAK-003 vaccination elicited multiple non-overlapping, unique humoral immune responses. Data support including parameters in addition to NAbs to better assess vaccine-induced humoral responses.

govregistration:NCT01511250, NCT02302066, NCT02747927, NCT03423173.