New vaccines against bacterial toxins.

Abstract

Chemically detoxified bacterial toxins are the main or the sole components of several vaccines such as diphtheria, tetanus, pertussis, and cholera. Other toxins are good candidates for novel vaccines, such as the vacuolating cytotoxin of Helicobacter pylori 1. Recently, genetic manipulation of the toxin’s genes has been used to obtain molecules that are already non toxic and do not require chemical treatment for detoxification. This approach has been successful for pertussis2, diphtheria3, cholera and LT toxins4. Preclinical and clinical studies have shown that these molecules have several advantages over the conventional chemically detoxified vaccines. Generally, they are much more immunogenic and induce an immune response, that recognizes better the native toxin molecules. Non toxic derivatives of cholera toxin and LT, in addition to being good candidates for antidiarrheal vaccines, are also mucosal adjuvants5. Therefore, genetically detoxified bacterial toxins not only are good candidates to improve existing vaccines, but they represent new tools for the development of innovative vaccines targeted to the mucosal system.