ABSTRACT: This experiment was designed to systematically evaluate the immunomodulatory effect of water extract of Artemisia annua L. (WEAA) on sheep, both in vivo and in vitro, and to determine the involvement of the TLR4/NF-κB signaling pathway in mediating these effects. In experiment 1, 32 female sheep (Dorper × Han, 3 months old, 24 ± 0.09 kg each) were designated to 4 groups, with each group receiving a basal diet supplemented with, respectively, 0 (control group), 500, 1000, and 1500 mg/kg WEAA. The serum, liver, and spleen immune indicators and related gene expressions were measured. In experiment 2, the peripheral blood lymphocytes (PBLs) were processed with WEAA (0, 25, 50, 100, 200, and 400 μg/mL), with six replicates assigned to each concentration group, then the cell viability, im
