Fig 3.

Coexpression of ROP16 and GRA15 enhances parasite susceptibility within IFN-γ- and TNF-α-stimulated macrophages. (A) C57BL/6 BMDMs were stimulated with IFN-γ (10 ng/ml) and TNF-α (25 ng/ml) for 20 h in 20% L929 medium (final concentration of G-CSF, 9 ng/ml). Before infection, the medium was replaced and infection with the indicated luciferase-expressing strains (MOI, ∼0.2) occurred in medium without cytokine or L929 in triplicate; 24 h later, luciferase activity was measured in the cell lysate. The luciferase activity obtained in stimulated macrophages is normalized to the mean luciferase activity observed in nonstimulated macrophages (no stimulation = 1). The mean + SD of the triplicates for each parasite strain is plotted. Significance was addressed by analysis of variance testing; indicated is the P value obtained for the II+ROP16_I strain in stimulated macrophages. (B) As in panel A, but Stat6^−/− (B6) and LysM-cre Stat3^fl/fl (B6) mice were assayed. P values were calculated with a two-tailed Student t test comparing differences between parasite strains.