The method of immunization for the control of infectious diseases in which naked plasmid DNA is injected as the """"""""immunogen"""""""" has been tested in a limited number of viral models and the results of these initial studies have caused much excitement. Plasmid DNA immunization promises to offer a unique method of stimulating both humor and cellular immune responses and it represents an attractive alternative to conventional approaches of vaccine development. Indeed, the ability to indue a specific cell-mediated immune response is a system an unfulfilled goal of many vaccine formulations acceptable for clinical use. This is critical consideration in vaccine development, as a cell-mediated immune response is required for the elimination of most intracellular pathogens. In our Phase I study w4e successful demonstrated that immunity to the intracellular pathogen Listeria monocytogenes can be induced by genetic immunization using plasmid DNA encoding a virulence factor for immunization. This immunization lead to the development of cytotoxic cells as measured in vitro and to protective immunity against challenge with viable L. monocytogenes. In our proposed Phase II studies we will expand these studies in order to optimize and validate the use of this promising approach to develop protective cell-mediated immunity to facultative intracellular pathogens.
Vaccines for the control of many infectious agents remain to be developed. Most notable is the absence of vaccines that can cause the development of protective cell-mediated immunity to intracellular pathogens. Development of improved reagents for genetic immunization is required as is the demonstration that this technology is suitable for effective immunization against facultative intracellular parasites.
