Galactose epimeraseless (GalE) mutant G30 of Salmonella typhimurium is a good potential live oral vaccine carrier for fimbrial antigens

The plasmid pFM205 encoding the cloned K88ab gene cluster from an enterotoxigenic Escherichia coli has been introduced into Salmonella typhimurium strain G30. The G30/pFM205 derivative has been shown to efficiently express the K88 pilus and this strain has been used for immunizing mice. Mice were immunized orally with live bacteria, intraperitoneally with formalin-killed bacteria, or orally with live bacteria followed by an intraperitoneal booster with killed organisms. All immunizations resulted in good antibody responses to K88 in the serum, however, only those immunizations involving an oral dose produced a significant antibody response in the gut. These results suggest that S. typhimurium strain G30 is a suitable carrier for producing intestinal antibodies to fimbrial antigens by oral immunization with live organisms.