Attenuated bacteria as a DNA delivery vehicle for DNA-mediated immunization

Previously, Shigella carrier 15D was shown to deliver a mammalian DNA expression plasmid to cultured cells with subsequent production of the plasmid-encoded foreign protein. In this study, we report in vivo delivery of a DNA expression plasmid to mucosal tissue results in the stimulation of immune responses against the plasmid-encoded foreign antigen. Splenocytes from mice receiving two intranasal inoculations of 15D carrying pCMV beta showed proliferative responses to the plasmid-encoded Escherichia coli beta-galactosidase. In addition, antibody specific for beta-galactosidase was detected in pooled sera collected from 15D (pCMV beta) infected mice.