“…Generally, there is agreement in the literature that severe disease is associated with T cell dysregulation and an uncontrolled inflammatory response (Lei et al, 2015;Mendoza et al, 2019). Specifically, patients with severe or fatal disease have lower numbers of CD3 + and CD4 + T lymphocytes (Liu et al, 2017a), an increased proportion of regulatory T cells (Yi et al, 2015), enhanced myeloid-derived suppressor cell-associated T cell impairment (Li et al, 2018b), and elevated serum cytokines such as CXCL10, granulocyte colony-stimulating factor (G-CSF), interleukin (IL)-6, MIP-1a, and MCP-1 (Liu et al, 2013;Liu et al, 2017a). In terms of B/plasmablastic cells, there is limited evidence that supports adaptive immune deficiency due to the dysregulation of B cell composition and disruption of B cellmediated humoral immunity, which can be featured as a hallmark of fatal SFTS outcome (Song et al, 2018;Suzuki et al, 2020).…”