Protection in a gerbil model of amebiasis by oral immunization with Salmonella expressing the galactose/N-acetyl D-galactosamine inhibitable lectin of Entamoeba histolytica.

Infection with the enteric parasite Entamoeba histolytica can result in colitis and dysentery as well as abscesses at extra-intestinal sites. An effective vaccine must be able to protect against both mucosal and systemic disease. In this study an attenuated Salmonella strain that expressed a portion of the GalNAc lectin of E, histolytica was used to orally immunize gerbils. Animals were challenged by intrahepatic injection of amebic trophozoites. A significant decrease in size of amebic liver abscesses was observed in orally immunized animals. Oral immunization with a Salmonella-based vaccine was as effective as systemic immunization for protection against systemic challenge.