The Salmonella enterica serovar Typhimurium outer membrane protein, denoted STY4528, has a molecular mass of 49 kDa encoding 447 amino acid residues and is highly immunogenic, evokes humoral and cell-mediated immune responses, and confers 100% protection to immunized rats against challenge with very high doses of Salmonella enterica serovar Typhimurium. Prediction methods suggest that members of this family possess a ß-barrel.