Memory CD8 T cells from naturally acquired primary dengue virus infection are highly cross-reactive

Cross‐reactive memory T cells induced by primary infection with one of the four serotypes of dengue virus (DENV) are hypothesized to have an immunopathological function in secondary heterologous DENV infection. To define the T‐cell response to heterologous serotypes, we isolated HLA‐A∗1101‐restricted epitope‐specific CD8+ T‐cell lines from primary DENV‐immune donors. Cell lines exhibited marked cross‐reactivity toward peptide variants representing the four DENV serotypes in tetramer binding and functional assays. Many clones responded similarly to homologous and heterologous serotypes with striking cross‐reactivity between the DENV‐1 and DENV‐3 epitope variants. In vitro‐stimulated T‐cell lines consistently revealed a hierarchical induction of MIP‐1β>degranulation>tumor necrosis factor α (TNFα)>interferon‐γ (IFNγ), which depended on the concentration of agonistic peptide. Phosphoflow assays showed peptide dose‐dependent phosphorylation of ERK1/2, which correlated with cytolysis, degranulation, and induction of TNFα and IFNγ, but not MIP‐1β production. This is the first study to show significant DENV serotype‐cross‐reactivity of CD8+ T cells after naturally acquired primary infection. We also show qualitatively different T‐cell receptor signaling after stimulation with homologous and heterologous peptides. Our data support a model whereby the order of sequential DENV infections influences the immune response to secondary heterologous DENV infection, contributing to varying disease outcomes.