Frequency of dengue virus-specific T cells is related to infection outcome in endemic settings.

Dengue is widespread in tropical and subtropical regions globally and imposes a considerable disease burden. Annually, dengue virus (DENV) causes up to 400 million infections, of which approximately 25% present with clinical manifestations ranging from mild to fatal. Despite its significance as a growing public health concern, developing effective DENV vaccines has been challenging. One reason is the lack of comprehensive understanding of the influence exerted by prior DENV infections and immune responses with cross-reactive properties. To investigate this, we collected samples from a pediatric cohort study in dengue-endemic Managua, Nicaragua. We characterized T cell responses in 71 healthy children who had previously experienced 1 or more natural DENV infections and who, within 1 year after sample collection, had a subsequent DENV infection that was either symptomatic or inapparent. Our study investigated the effect of preexisting DENV-specific T cell responses on clinical outcomes of subsequent DENV infection. We assessed DENV-specific T cell responses using an activation-induced marker assay. Children with only 1 prior DENV infection displayed heterogeneous DENV-specific CD4+ and CD8+ T cell frequencies. In contrast, children with 2 or more prior DENV infections showed significantly higher DENV-specific CD4+ and CD8+ T cell frequencies associated with inapparent rather than symptomatic outcomes in subsequent infection. These findings demonstrate the protective role of DENV-specific T cells against symptomatic DENV infection and advance efforts to identify protective immune correlates against dengue.