Siderophore Receptor IroN Is an Important Protective Antigen Against Salmonella Infection in Chickens

Abstract In iron-limiting environments, Salmonella enterica serovar Enteritidis and Salmonella enterica serovar Typhimurium synthesize and secrete several types of siderophore to trap trivalent ferric ions; these bacteria then express siderophore receptors called iron-regulated outer membrane proteins (IROMPs). In this study, we experimentally reproduced iron-limiting environments using a divalent metal chelator. IroN, one of the IROMPs, was purified by affinity chromatography with an anti-IroN-MAb-immobilized column. Thirty-day-old chickens were immunized intramuscularly with purified IroN from Salmonella Typhimurium mixed with Freund's incomplete adjuvant; the chickens were then challenged intravenously with Salmonella Enteritidis. The mortality rate of immunized chickens was 10%. On the other hand, that of control chickens was 80%. By Western blot analysis, specific IgG antibody responses against IroN of Salmonella Enteritidis were identified in chickens immunized with purified IroN. These results indi...