Live attenuated Shigella flexneri mutants as vaccine candidates against shigellosis and vectors for antigen delivery.

Up to now, no effective vaccine is available against shigellosis, a dysenteric syndrome caused by Shigella, a Gram-negative bacterium which invades the human colonic mucosa. About 40 years of research in the field have led to the conclusion that orally administered live Shigella vaccine strains are more effective in eliciting protection than killed bacteria given parenterally. Recently, the construction of promising new live attenuated vaccines has come with a better understanding of the fundamental determinants governing pathogenesis. As the development of new vaccine strategies requires knowledge of both pathogenesis and the immune response against infection, the current view of the pathogenic process of Shigella infection and the anti-Shigella immune responses elicited by the host are presented. The attempts in Shigella vaccine design are reviewed and, the future of these vaccines discussed.