2.3 Analyses of cytokines in SFTS and COVID-19 patients
To characterize the effect of SFTSV and SARS-CoV-2 infection on the production of serum cytokines in SFTS and COVID-19 patients, Interleukin (IL)-2, IL-4, IL-6, IL-10, IL-17A, interferon-γ (IFN-γ), and tumour necrosis factor (TNF-α) were measured using human Th1/Th2/Th17 CBA kits (BD Bioscience, San Diego, CA) according to the manufacturer’s instructions, with minor modifications. Sample acquisitions were performed with a FACS Canto II flow cytometer and analysed by FCAP Array software version 3.0 (BD Bioscience). All statistical analyses were performed using SPSS 22.0 (SPSS, an IBM Company). TGF-β was measured in the collected serum using a TGF-β-1 Human ELISA Kit (Thermo Fisher Scientific) according to the manufacturer’s protocols.
To compare the mean difference between patients with fatal and nonfatal SFTS disease and between patients with severe and critical and mild to moderate COVID-19 disease, we usually used a two-sample t-test. When using this method, we checked some assumptions, such as normality, equal variance, and independence. When these assumptions were not met, we used a nonparametric two-sample t-test called the Wilcoxon-Mann‒Whitney test.[7] P values<0.05 indicated statistical significance.