|
The cytolethal distending toxins(CDTs), constituting the most recently discovered family of bacterial protein toxins, are the important virulent factor of Gram-negative pathogenic bacteria. In present study, CDTs are found in several bacteria species, including Escherichia coli, Shigella dysenteriae, Salmonella, Campylobacter spedies, Haemophilus ducreyi, Helicobacter species and Actinobacillus actinomycetemcomitous. The founction of CDTs is that they have the ability to induce DNA double strand breaks (DSBs)in both proliferating and nonproliferating cells. By destroying DNA and activating cellular checkpoint, CDTs can prevent the transition between the G1 or G2 and M phase of the cell cycle irreversibly, causing distention and death of the target cells. In all cases, the genetic structure encoding CDTs activity includes three adjacent genes (cdt-A, cdt-B and cdt-C)which appear to be homologous in these species. Five cdt genetic variants, designated cdt-Ⅰ,cdt-Ⅱ,cdt-Ⅲ,cdt-Ⅳand cdt-Ⅴ, have been identified in Escherichia coli.In order to determine the epidemiological distribution of cytolethal distending toxin genes of Escherichia coli among Chinese Escherichia coli strains, Shigella strains and a part of Enterobacteriaceae strains, polymerase chain reaction (PCR) assay
|