ORAL SOMATIC TRANSGENE VACCINATION USING ATTENUATED SALMONELLA-TYPHIMURIUM

An attenuated strain of S. typhimurium has been used as a vehicle for oral genetic immunization. Eukaryotic expression vectors containing tr uncated genes of ActA and listeriolysin-two virulence factors of Liste ria monocytogenes-have been used to transform S. typhimurium aroA. Mul tiple or even single oral immunizations with such transformants induce d excellent cellular and humoral responses. In addition, protective im munity was induced with listeriolysin transformants. The quality of th e responses suggested a transfer of plasmid DNA from the bacterial car rier to the host. Such transfer was unequivocally shown in vitro with primary peritoneal macrophages. We describe a highly versatile system for antigen delivery, identification of protective antigens for vaccin ation, and efficient generation of antibodies against the product of o pen reading frames present on virtually any DNA segment.