Fig. 3.

NleH1 prevents pro-caspase-3 cleavage induced by TcdB. Caspase-3 activation was determined in cells transfected with nleH1 (pHM6-nleH1) or a gfp control (pEGFP-N1) and treated with 4 ng TcdB ml⁻¹ for 18 h; unchallenged cells were used as a control. (a) Cells were stained with anti-HA (green) to label HA-tagged NleH1 and anti-cleaved caspase-3 (red) and visualized by immunofluorescence. (b) The level of caspase-3 cleavage in transfected cells was determined by counting under an epifluorescence microscope. Black bars, TcdB-treated cells; white bars, unchallenged controls. Expression of NleH1 significantly prevented the cleavage of pro-caspase-3 when cells were treated with TcdB compared to mock-transfected cells or cells transfected with pGFP.