Toxic activity of the CdtB component of Haemophilus ducreyi cytolethal distending toxin expressed from an adenovirus 5 vector.

The Haemophilus ducreyi cytolethal distending toxin (HdCDT) catalytic subunit CdtB has DNase-like activity and mediates DNA damage after its delivery into target cells. We constructed a replication-deficient adenovirus type 5 (Ad5) vector expressing CdtB and investigated the toxic properties of this vector on HeLa cells. Ad5CdtB caused loss of cell viability, morphologic changes, and cell cycle arrest, findings similar to HdCDT intoxication. This confirmed that CdtB is responsible for the toxicity of the holotoxin when expressed in cells following transduction by an adenoviral vector, and indicated a possible potential of this novel strategy in studies of activity of intracellular products and in gene therapy of cancer.