Competitive immunoassay for staphylococcal enterotoxin A using capillary electrophoresis with laser-induced fluorescence detection.

Staphylococcal enterotoxins are a family of toxic proteins secreted by S. aureus. Using capillary electrophoresis (CE) linked with laser-induced fluorescence, a highly sensitive and selective assay using antibody-antigen recognition was developed for the determination of Staphylococcal enterotoxin A. Staphylococcal enterotoxin A (SEA) was chemically labeled with fluorescein and the product was used as a fluorescent tracer. A competitive assay was developed to detect SEA at concentrations between 0.3 nM and 6.5 nM with standard deviations of less than 5%. The detection limit was found to be 3 amol with the potential improvement by further optimization of the assay. No cross-reactivity between staphylococcal enterotoxin B and the SEA antibody was found at the concentrations used for the CE immunoassay.