Advantages of immunoglobulin Y for the detection of Staphylococcal enterotoxin A in a double‐antibody sandwich enzyme‐linked immunosorbent assay

Summary To determine the amounts of staphylococcal enterotoxin A (SEA), a novel and sensitive enzyme‐linked immunosorbent assay (ELISA) was developed. Protein A, which is produced by Staphylococcus aureus, interferes with the reaction between SEA and anti‐SEA immunoglobulin G (IgG), resulting in a false‐positive reaction. Chicken IgY was introduced as a capture antibody in the sandwich ELISA system, as IgY binds less efficiently to protein A. When the anti‐SEA IgG antibody was used as the capture and detection antibodies (IgG‐IgG ELISA), the background levels of protein A increased, thus resulting in a false‐positive reaction. A 0.01 ng mL−1 concentration of protein A significantly increased the absorbance value of the blank wells. When the anti‐SEA IgY antibody was used as the capture antibody, 1000 ng mL−1 of protein A did not affect the absorbance value. The ELISA system using anti‐SEA IgY as a capture antibody and anti‐SEA IgG as a detection antibody (IgY‐IgG ELISA) showed a detection limit of <0.25 ng mL−1 and a creditability of R2 = 0.98. These findings demonstrate the advantage of chicken IgY for the detection of SEA by means of double‐antibody sandwich ELISA.