Development of Recombinant Flagellar Antigens for Serological Detection of Salmonella enterica Serotypes Enteritidis, Hadar, Heidelberg, and Typhimurium in Poultry

Abstract

Accurate and fast detection of harmful Salmonella is a major concern of food safety. Common Salmonella serotypes responsible for human associated foodborne outbreaks are S. Enteritidis, S. Hadar, S. Heidelberg, and S. Typhimurium are also commonly isolated from poultry. Serology is commonly used to monitor disease in poultry, therefore application of Salmonella serotype-specific test will have added value in Salmonella surveillance or monitoring vaccine efficacy. Recombinant flagellins were purified to be used as antigens in an ELISA. In this study, an ELISA was developed for the serological detection of S. Enteritidis. Once optimized, 500 ng of purified recombinant S. Enteritidis flagellin and a 1:64 dilution were determined to be optimal for testing sera. A negative baseline cutoff was calculated to be an optical density (OD) of 0.35. All sera from birds with history of S. Enteritidis exposure tested positive and all sera from chickens with no exposure tested negative to this Salmonella serotype. Current ELISA for serological detection of Salmonella suffers from cross reactivity inherent in lipopolysaccharide (LPS) or whole cell antigen based serological tests. This new ELISA eliminates common cross reactivity by focusing specifically on the flagellins of the Salmonella serotypes common in poultry and associated with foodborne outbreaks.

Keywords

• Salmonella
• ELISA
• poultry
• serotype
• Enteritidis