FIG. 3.

Fragmentation of DNA in human and murine macrophages (about 2 × 10⁴ cells per well in 96-well plates) as assayed by ELISA. Data are means ± standard deviations of duplicate samples from one representative experiment of two. Shown are results for infected murine macrophages J774 at 12 h p.i. at an MOI of 100 (A), J774 cells treated with purified ClyA for 12 h (B), and infected human macrophages U937 at 6 h p.i. at an MOI of 100 (C). Bars: 1, vector strain MC1061/pUC18; 2, ClyA-expressing strain MC1061/pYMZ80; 3, Tris-HCl buffer (20 mM, pH 7.5); 4, purified ClyA protein (20 μg ml⁻¹); 5, MC1061/pUC18; 6, MC1061/pYMZ80.