Figure 6From: Construction of Bordetella pertussis strains with enhanced production of genetically-inactivated Pertussis Toxin and Pertactin by unmarked allelic exchangeCHO-cell clustering test. The cells were grown to near confluence then dilutions of PT were added and the clustering was scored after 2 days. A: 800 ng PT (strain Bp-WWC). B: Control, no PT added. C: 2.6 pg wt PT (strain Tohama) corresponding to the limit of detection. D. 43 pg wt PT (strain Tohama)Back to article page