Development and application of enzyme-linked immunosorbent assay for specific detection of Salmonella enteritidis infections in chickens based on antibodies to SEF14 fimbrial antigen.

A double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) was developed to detect antibodies to the SEF14 fimbrial antigen (SEF14-DAS ELISA) and was evaluated for its use in the specific detection of chicken flocks infected with Salmonella enteritidis. The SEF14-DAS ELISA successfully discriminated between chickens experimentally infected with S. enteritidis and those infected with S. panama or S. typhimurium, although the SEF14 responses in adult birds infected with S. enteritidis were detectable but low. In contrast, ELISAs used to detect antibodies to lipopolysaccharide (LPS) and flagella were unable to discriminate between the infected groups of chicks and adult birds infected with different Salmonella serotypes. LPS and flagellar responses were low and variable in chicks, whereas in adult hens they were found to be consistently strong. When flocks naturally infected with S. enteritidis were tested by the SEF14-DAS ELISA and ELISAs to detect LPS and flagellar antibodies, it was found that they could all identify the infected flocks, although there was little correlation between individual serum samples. The study shows that the SEF14-DAS ELISA may offer advantages over existing assays with comparable sensitivities coupled with higher specificities for the serological detection of S. enteritidis-infected chicken flocks.