The meeting that provided the material for this book was the 58th Symposium of the Federation of European Microbiological Societies (FEMS) entitled MOLECULAR PATHOGENESIS OF GASTROINTESTINAL INFECTIONS which was held in Helsingor, Denmark from 2nd to 4th September, 1990. The aim of this meeting was to bring together scientists from a range of discipline- microbiology, cell biology, molecular biology and immunology - to consider how microbes, including parasites, colonize and infect the gastrointestinal tract. The programme was designed to focus particular attention on the range of strategies whereby enterovirulent bacteria and parasites colonize the gastrointestinal mucin layer, how they adhere to and penetrate the epithelial layer by entering the cells or passing between them, and how various protein toxins may facilitate these processes. Speakers were especially encouraged to highlight the recent expansion in our knowledge of the molecular mechanisms by which enterotoxigenic and enteropathogenic Escherichia coli, shigellae, salmonellae and Yersinia enterocolitica cause intestinal disease. There were also discussions of recently-discovered gastrointestinal pathogens such as Clostridium difficile and Helicobacter pylori as well as accounts of how virulent determinants can be used to develop new diagnostic methods based on DNA gene probes and the polymerase chain reaction (PCR). These presentations provided the basis for the chapters in this book.

A very early step in microbial colonization and pathogenesis is that involving recog nition of the host by the microbe. In the final analysis such recognition is due to interaction between specific molecules on the two sides, without which host and microbe would ignore each other. It is therefore exciting to learn the rules that govern host-microbe interaction at to a large extent determines whether or not we are infected by the molecular level, which influenza virus, leishmanias, staphylococci and other pathogens. This book is a compendium of the addresses delivered at a symposium on molecular interaction at Porvoo, Finland in August 1991. Realizing that there are no a priori differ ences in receptor recognition in viruses, eukaryotic parasites and bacteria, we freely inter mingled these microbes at the symposium, and in this book. We found the interdisciplinary discussions and comparisons both educative and stimulating. Thus the book is divided into parts that focus on host cell receptors, on microbial recognition molecules and molecules that mediate microbial interaction with a host cell receptor and, briefly, on the molecular events that follow. Although many microbes and many cellular receptors are missing from the book -owing to the limited duration and size of the symposium -the articles presented here constitute an impressive body of examples of how initial host-microbe interaction can come about. We believe that as such the book is a useful and interesting overview of the mechanisms and principles involved in these interactions.

The 5th Pathogenic Neisseriae Conference was held in Noordwijkerhout, The Netherlands, on 15-18 September 1986. It followed San Francisco - USA (1978), Hemavan - Sweden (1980), Montreal - Canada (1982), Asilomar - USA (1984). These conferences will continue to be held in the foreseeing future. The reason for this is because studying pathogenic Neisseriae enables research workers to look at many aspects of bacterial infectious diseases. These aspects include: - Epidemiology and vaccination (section 1) - Genetic aspects of antigenic diversity (section 2) - Outer membrane proteins and IgA-protease (section 3) - Lipopolysaccharides, H8 antigen and peptidoglycan (section ~) - The application of all this knowledge to study pathogenesis (section 5) N. gonorrhoeae has become an important model organism to study mucosal bacterial infectious diseases. Basic knowledge about the bacterial surface, gene- tics and physiology is linked to pathogenic mechanisms such as adhesion to and invasion of epithelial cells, interaction with complement and phagocytic cells and mucosal immune mechanisms. This will continue to be an important research field in the near future. N. meningitidis has become an important model organism to study the epide- miology of potentially epidemic bacterial diseases and against which new type of vaccines are being developed such as outer membrane protein vaccines. The above mentioned topics are covered by papers presented at The 5th Path- ogenic Neisseriae Conference, 1986. I would like to thank Marijke van de Nadort without whom it would have been much harder or even impossible to organize such a meeting.