IFNG and hemorrhagic fever with renal syndrome: In this study, we defined five novel HTNV-NP CTL epitopes restricted by the major HLA class I molecules in Chinese Han population; we provided, for the first time, a quantification of the HTNV epitope-specific IFN-γ–secreting CD8+ T cells in HFRS patients; we analyzed the kinetics changing, the activation, and proliferation capacity of the epitope-specific CD8+ T cells and evaluated the associations between the epitope-specific CD8+ T-cell frequencies and the different outcomes of the HFRS severity.