Fig. 6.

The levels of principal cytokines involved in NK cell activation and function were increased during the early stage of SFTSV infection A, B, C and D. The plasma cytokine levels of IL-15, IFN-α, IL-18 and IFN-γ were evaluated in the healthy controls (n = 15) and in the patients with mild (n = 15) or severe (n = 14) SFTS upon admission (left panels of A, B, C and D) and at different time points during their entire hospital stays (middle panels of A, B, C and D). Data are shown as the mean ± SD. The dashed line represents the mean of the healthy controls. Right panels of A, B, C and D. The plasma cytokine levels of IL-15, IFN-α, IL-18 and IFN-γ were evaluated during the acute and recovery phases in all 29 patients. Statistical analysis was performed using the two-tailed unpaired t test, multiple t tests or paired t test. The level of significance is indicated as follows: ns, not significant; *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001