Cytolethal distending toxin as virulence factor, protective antigen, and target for vaccine development

Correspondence: Teresa Lagergard Medicinaregatan 7A, Box 435, Institute of Medicine, Department of Microbiology and Immunology, Sahlgrenska Academy, University fg Gothenburg, 405 30 Goteborg, Sweden Tel +46 31 786 6220 Fax +46 31 786 6210 Email teresa.lagergard@microbio.gu.se Abstract: This review explores the cytolethal distending toxin (CDT) as a virulence factor, protective antigen, and a vaccine candidate in diseases caused by the following bacterial pathogens: Haemophilus ducreyi (HdCDT), Aggregatibacter actinomycetemcomitans, Campylobacter jejuni, and Helicobacter hepaticus. The review highlights some of the important evidence indicating that CDT is not only a commonly invoked virulence factor involved in pathogenesis of infection caused by these bacteria, but is also a protective antigen, such that specific antibodies will neutralize cell damage caused by the toxin. This justifies the development of toxoids as vaccine candidates. The first immunogenic toxoid was produced by formaldehyde treatment of HdCDT and has been used to study the involvement of antibodies in protection against infection and its use as a future vaccine component. The development of such toxoid vaccines may facilitate the studies of protection and immunoprophylaxis in diseases caused by CDT-producing bacteria.