2.5 Virus isolation
The supernatant of Vero cells (African green monkey kidney cells) grown into a single layer was discarded, washed once with PBS, and incubated with 500 µL of patient serum for 2 h, and then discarded. Virus maintenance solution (DMEM containing 2% fetal bovine serum) was added and cultured at 37 °C under 5% CO2, and cytopathic effects (CPEs) were observed daily. Tick suspensions that were positive SFTSV by the nucleic acid test were filtered through a 0.22-µm bacterial filter and were added to the Vero cells. Cells were collected, RNA was extracted, reverse transcription was performed, and PCR detection was performed to verify successful infection. The infected cells positive for SFTSV were stored at −80 °C until use.