Effect of BHV-1 infection on FasL, Fas expression and Bid cleavage in MDBK cells. (A) Fas and FasL expression in cells mock-infected or BHV-1-infected (2 MOI) for indicated hours (left panel) or different MOI for 48 h (right panel) were analyzed by Western Blot Analysis. Data are representative of three separate experiments. (B) Bid cleavage to tBid in BHV-1-infected cells. Cells were treated as A and subjected to Western Blot Analysis. β-actin was used as internal controls. Data are representative of three separate experiments. (C) tBid expression in MDBK cells. Cells were pre-treated with the caspase-8 inhibitor and infected with BHV-1 for 48 h, and then analyzed by Western Blot Analysis. (D) Effect of caspase-8 inhibitor on the activity of caspase-9. Cells were pretreated with Z-IETD-FMK for 2 h then infected BHV-1 for 48 h. Caspase-9 activity was measured by a colorimetric assay kit. Data are mean ± SD from three independent experiments. ** p < 0.01 versus BHV-1 infection alone.