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

A Renewable Biosensor Based on LNA-Aptamer Hybridization for the Detection of Salmonella enteritidis in Penaeus vannamei

Salmonella enteritidis (SE) is an important factor causing foodborne disease, and electrochemical sensors have drawn much attention for SE prevention and detection due to their many advantages. A renewable electrochemical sensor using specially designed locked nucleic acids (LNA) as linkers for the detection of SE was proposed to improve the reusability and reproducibility of biosensors. One end of the LNA was designed as an anchor to attach to modified electrodes through the sulfhydryl group; the other end was used to match with a short segment of SE aptamers, which will allow for the convenient renewal of occupied aptamers by raising the temperature. Results revealed that the manufactured biosensor had good stability, reproducibility, and selectivity in addition to a linear range of 6 × 10¹-6 × 10⁵ CFU/mL and a limit of detection (LOD) of 20.704 CFU/mL. The recovery rate of SE for the real sample varied from 98.84% to 134.82% without exceeding 16.27% in the relative standard deviation (RSD). The proposed biosensor appears to be a promising tool for foodborne pathogen detection.

Mucosal humoral immunity to experimental Salmonella enteritidis infection in the chicken crop

In this report, we show that chickens, infected with Salmonella enteritidis (SE) by oral gavage, produce secretory immunoglobulin As (sIgAs) that specifically bind to numerous SE antigens. Chickens infected with SE showed strong sIgA response against flagella in both bile and crop. The optical density values of enzyme-linked immunosorbent assay (ELISA) tests in positive bile and crop were 1.17 and 0.38, respectively, and were significantly different from those of negative samples. Western immunoblotting revealed that approximately 13.5-, approximately 56-, approximately 62-, approximately 80-, and approximately 143-kD polypeptides were immunodominant proteins in bile, whereas approximately 56-, approximately 62-, and approximately 80-kD polypeptides were found to be strong antigens in crop. These results indicate that the crop may function as another site for mucosal immunity, and the SE flagella-based ELISA of crop samples can provide a useful screening test of SE exposure in chickens.