To start with, we feel that we should explain why the book has been entitled Cholera Toxins. In fact, the enterotoxin secreted by Vibrio cholerae, which is p- marily responsible for causation of the disease, is conventionally known as or referred to as cholera toxin, or CT. By using the word "toxins" (in its plural form), we wanted to cover all of the different types of toxins-and not just CT-produced by V. cholerae. We could have used the title Toxins of Vibrio cholerae, but we believe that Cholera Toxins is simpler and equally as expressive. However, due to its relative importance, the story of CT covers most of this book. Also, compared to all other toxins of V. cholerae, CT has been investigated more extensively. This book was jointly written by us. It is not a multiauthor book in which each expert writes one chapter. In that respect our task is harder. On the other hand, it has given us the unique opportunity to present the entire subject in the way that we conceived it. Besides, our objective is to cater to the needs of not only active research scientists but also students from different disciplines-microbiology, molecular physiology and pharmacology, basic medicines, etc. -and as such, we have attempted to present the subject in a way that will be appreciated by general readers. Further, we have provided some information that students and predoctoral researchers may find useful at the end of the book.

This book provides a detailed account of the physico-chemical properties and biological functions of the outer membrane vesicles (OMVs) of different pathogenic and non-pathogenic Gram-negative bacteria. It also includes an authentic record of the first systematic study that discovered the mechanism of OMV formation by a pathogen, "Vibrio cholerae," and proposed that the process represented a novel secretory activity of bacteria. Furthermore, the authors present clinical and laboratory data on the use of OMVs as immunogens, as effective and licensed vaccines against "Neisseria meningitidis" serogroup B infections and on the development of more effective vaccines against other human and animal pathogens including "Vibrio cholerae. "This volume thus bears witness to the emerging revolution in the field of vaccines against pathogens and closes with a discussion of open questions and future research on OMVs.