Toxoplasma decreases prolyl hydroxylase activity. A, Renilla-ODD transfected cells were mock or parasite-infected and grown at 21 or 3% O2. Lysates were collected 24 h later, and luciferase activity was measured. Shown are the averages and standard deviations of six independent experiments. *, p < 0.05 Student's t test. B, HFFs were mock infected, CoCl2-treated, Toxoplasma-infected (Toxo) for 18 h, or MG132-treated for 2 h. C, the lysates were prepared and Western blotted with antibodies against either total HIF-1α, Pro402-OH HIF-1α, or Pro564-OH HIF-1α or actin as a loading control. Shown are representative blots from three independent experiments. D, cells cotransfected with pGBD-HIF-1α737–826 and the p5xGRE-luc reporter were either mock infected, Toxoplasma-infected, or shifted to 3% oxygen for 24 h. The lysates were collected, and luciferase activity was measured. Shown are the averages and standard deviations of three independent experiments. *, p < 0.05 Student's t test.