To explore the role of DENV immunity in protection vs. pathogenesis during ZIKV infection, we challenged DENV2-immune Ifnar1−/− mice (28 days post infection) with ZIKV strain FSS13025 and determined antigen-specific CD8+ T cell responses and viral titers in sera and tissues at day 3 after ZIKV challenge. The gene discussed is CD8A; the disease is infection.