Simplified preparation of a specific S. enteritidis antigen for ELISA and other immunological techniques

This study was conducted to prepare a specific S. enteritidis antigen (FG-Antigen) for the serological detection of S. enteritidis infections in chicken flocks. This antigen (FG-Antigen) consistent mainly of the flagellar fraction H:g and partly of the fimbrial fraction SEF14 from a S. enteritidis-phage type 4 strain. The initial steps followed in the preparation of this antigen were conducted based on a previously described procedure, which involved the application of heat at 60 degrees C. The purification process (filtration and concentration) enabled the exclusion of the cross-reaction causing LPS antigens from the preparation and allowed the retention of S. enteritidis-specific antigens composed of fimbria and H:g fractions. As a result, no cross-reaction with S. typhimurium nor with S. gallinarum was exhibited by the prepared FG-antigen. To characterize and determine its specificity, the following laboratory tests were conducted: indirect ELISA, immunoblotting and a SEF14 agglutination test. In these examinations, rabbit and chicken reference sera as well as chicken field sera and absorbed hyperimmune sera against H:g-carrying serovars were used.