Vaccination against enteric bacterial diseases

We review evidence that the systemic and mucosal immune systems of the body are compartmentalized. The development of immunity against an antigen at one mucosal surface may lead to the appearance of that immunity at other mucosal surfaces. In order to attain good protective immunity against a bacterial enteropathogen, it may be necessary to induce such immunity through the mucosal immune system of the gut. Earlier attempts to elicit protective immunity against bacterial enteropathogens by parenteral vaccination are reviewed. The modern approach involves oral administration of antigen. Such antigen may consist of killed bacteria or--more effectively--live, attenuated bacteria bearing antigens of interest. Such bacteria may be enteropathogens attenuated by mutation, either general or site-directed, or hybrid strains in which a bacterial carrier expresses an antigenic determinant of interest from cloned DNA. While good progress has been made in the comprehension of the requirements for effective vaccination against enteropathogenic bacteria, future work will produce more effective carrier strains than are currently available.