To explore the effects of lipoxygenase (LOX) on severe fever with thrombocytopenia syndrome virus (SFTSV) in human umbilical vein endothelial cells (HUVECs).

The CCK-8 assay was used to assess the cytotoxicity of LOX in HUVECs. Real-time quantitative PCR (qPCR) was adopted to detect the replication of viral RNA in cells. The infection rate of SFTSV to HUVECs was observed via indirect immunofluorescence assay (IFA). The expressions of intracellular viral NP protein and autophagy related proteins microtubule-associated protein 1 light chain 3 (LC3) and adenosine 5’-monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) were detected via Western blotting. Lipid metabolomics was used to analyze the differences in expressions of intracellular metabolites in the SFTSV-infected Huh 7 with or without LOX treatment.

The results of CCK-8 showed no obvious cytotoxicity to HUVECs with LOX≤8 mg/mL. With the increase of LOX concentrations, the viral RNA level, viral infection rate, and expressions of SFTSV nucleoproteind (NP) protein were gradually decreased, respectively. The autophagy reaction was activated in SFTSV-infected HUVECs, evidenced by the increased expression level of LC3 Ⅱ protein. Compared with the untreated group, LOX treatment resulted in decreased levels of LC3 Ⅱ and AMPK phosphorylation, and enhanced phosphorylation of mTOR in SFTSV-infected HUVEC.

LOX negatively regulates autophagy by inhibiting AMPK/mTOR signaling pathway, thereby inhibiting SFTSV replication.