Immunization of mice with live oral vaccine based on a Salmonella enterica (sv Typhimurium) aroA strain expressing the Escherichia coli O111 O antigen.

Shiga toxin-producing Escherichia coli strains of serogroup O111 are the most frequently isolated non-O157 strains causing outbreaks of gastroenteritis with haemolytic uraemic syndrome (HUS). O antigen is a major antigen in Gram-negative bacteria, and it has been shown that O111 is a protective antigen. Attenuated Salmonella enterica sv Typhimurium aroA strain STM-1 was used as a live carrier to express the E. coli O111 O antigen. Mice immunized intraperitoneally produced serum immunoglobulin G, and mice immunized orally produced serum immunoglobulin G and secretory immunoglobulin A in the intestine against E. coli O111 cells as determined by enzyme-linked immunosorbent assays.