Quantitative and qualitative differences in anti-Envelope IgG-secreting cells distinguish subclinical and hospitalized dengue in a Cambodian pediatric cohort.

Dengue virus (DENV) infection can result in outcomes ranging from subclinical infection to life-threatening illness, yet the antibody features mediating protection in humans remain poorly defined. Dengue virus envelope protein (E) forms homodimers on the virion surface and elicits both neutralizing and non-neutralizing antibodies from IgG-secreting cells (IgG-SC). How the developing antibody response at the monoclonal level contributes to protection is unknown. We profiled single IgG-SC responses in a Cambodian pediatric cohort by measuring affinity and serotype cross-reactivity of secreted antibodies from patients with subclinical or hospitalized dengue during acute DENV1 or DENV2 infection. Using droplet-based microfluidic imaging, we analyzed over 3,300 single IgG-SC. Hospitalized patients exhibited significantly lower numbers of IgG-SC, despite comparable IgG secretion rates and similar frequencies of DENV E-specific antibody-secreting cells relative to subclinical cases. In hospitalized patients, the affinity of IgG-SC for the DENV1 E-dimer was 3-fold lower compared to subclinical cases. Notably, antibodies recognizing quaternary epitopes-binding E-dimers but not monomers-were detected exclusively in subclinical cases, whereas hospitalized patients predominantly produced monomer-reactive antibodies. These findings suggest that dengue severity may be linked to the inefficient generation of sufficient numbers of high-affinity, broadly reactive antigen-specific IgG-SC during post-primary infection.