Enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies against Salmonella enteritidis in chicken blood or egg yolk.

Tracing of flock infection remains one of the most serious unsolved problems of controlling salmonellosis in poultry. In order to overcome this problem, a serological test kit for the detection of antibody to Salmonella enteritidis (1, 9, 12:[f], g, m, [p]:[1, 7]) in chicken flocks was developed. In this study, samples of antisera and the yolk of eggs from different chicken flocks were tested with the ELISA kit, and the resulting flock profiles were compared. The test system clearly allowed a differentiation between flocks which were positive and flocks which were negative for S. enteritidis. Sera from stocks infected with S. typhimurium (1, 4, (5), 12:i:1, 2) or S. heidelberg (1, 4, (5), 12:r, 1, 2) were also analysed in order to determine the relative cross-reactivity in the test. No false-positive results could be shown in the case of S. heidelberg; cross-reactions with antibodies against S. typhimurium were found in 2.5% to 10% of the samples from a particular flock. The test kit could also be used for the analysis of egg yolk samples without time-consuming purification procedures. Specific antibodies were detected in high dilutions of positive egg yolks, thus enabling a rapid screening for S. enteritidis-positive chicken flocks.