Molecular approaches for safer and stronger vaccines

Progress in molecular biology and biotechnology is making possible the development of new vaccines or the improvement of already existing ones. Recombinant DNA technology, genetic attenuation of bacterial and viral pathogens and their use as vectors for heterologous proteins, expression of microbial antigens in transgenic edible plants, and naked nucleic acid technology represent the most popular approaches hitherto adopted. A successful biotechnological approach to the development of new and improved vaccines has been based on genetic detoxification of bacterial toxins, such as the toxin of Bordetella pertussis, the heat-labile enterotoxin of Escherichia coli, and the toxin of Vibrio cholerae. Genetically detoxified Bordetella pertussis is now included in a commercially available acellular vaccine against pertussis. Genetically detoxified Escherichia coli and Vibrio cholerae have been shown to behave as very strong and safe mucosal adjuvants and are now entering the clinical stage. These results demonstrate that a rational molecular approach to the development of safer and stronger vaccines is feasible.