The clinical and immunological characteristics in fatal severe fever with thrombocytopenia syndrome virus (SFTSV) infection

Objective: This study aimed to make a comprehensive evaluation of peripheral immune profiles for further un-derstanding the immunopathogenesis of severe fever with thrombocytopenia syndrome (SFTS). Methods: Forty-seven patients with SFTS virus infection were included, of which 24 were deceased. The per-centages, absolute numbers, phenotype of lymphocyte subsets were detected by flow cytometry. Results: In patients with SFTS, the numbers of CD3+T, CD4+T, CD8+T and NKT cells were decreased compared with healthy controls (HCs), accompanied with highly active and exhausted phenotypes for T cells, and over-proliferating plasmablasts. High inflammatory status, dysregulation of coagulation and host immune response were more obvious in deceased patients than that of survivors. Higher levels of PCT, IL-6, IL-10, TNF-alpha, APTT, TT and the occurrence of hemophagocytic lymphohistiocytosis were poor prognostic indicators of SFTS. Conclusions: The evaluation of immunological markers in combination with laboratory tests has critical value for selecting prognostic markers and potential treatment target.