IDO1 and acute kidney injury: For example, in PUUV-infected patients, high plasma levels of IL-6 were associated with more severe disease [38]; in acute PUUV infections, elevated levels of indoleamine 2,3-dioxygenase (IDO) were associated with more severe AKI, more pronounced inflammation, and longer hospitalization in acute PUUV infections [39]; and in HTNV-induced HFRS, plasma cf-DNA levels were associated with HTNV loads and disease severity [40].