CD8⁺ T-cells target the Crimean-Congo haemorrhagic fever virus Gc protein to control the infection in wild-type mice.

Abstract

Crimean-Congo haemorrhagic fever (CCHF) is a serious viral hemorrhagic fever caused by the CCHF virus (CCHFV). Spread by the bites of infected ticks or handling of viremic livestock, human disease is characterized by a non-specific febrile illness that can rapidly progress to fatal hemorrhagic disease. No vaccines or antivirals are available. Case fatality rates can vary but can be higher than 30%, although sub-clinical infections are often unrecognized and unreported. Yet, while most humans infected with CCHFV will survive the infection, often with little-to-no symptoms, the host responses that control the infection are unknown. Here we investigated the role of cellular immunity in control of CCHFV infection in an immunocompetent mouse model. We found that CD8⁺ T-cells are crucial for efficient control of the acute infection and rapidly acquired CCHFV-specific antiviral effector functions such as production of antiviral cytokines and degranulating in response to CCHFV peptides. We further identified the minimal CD8⁺ T-cell epitopes in the viral Gc proteins and that infection of mice lacking IFNγ resulted in worsened disease and higher viral loads. Together our data suggest that CD8⁺ T-cells are important for control of acute CCHFV infection likely through production of antiviral cytokines. This work was supported by the Intramural Research Program of the NIH.