A superantigen bioassay to detect staphylococcal enterotoxin A.
Current detection methods for enterotoxins of Staphylococcus aureus are labor intensive and limited in sensitivity. Furthermore, these immunochemical protocols fail to adequately detect heat-treated enterotoxins. Staphylococcal enterotoxins cause severe gastrointestinal illness at relatively low concentrations and retain toxigenicity even after heat treatment. Presented here is a novel method to detect staphylococcal enterotoxin A (SEA). This method is a bioassay that exploits SEA's activity as a superantigen in that it induces in cytotoxic T lymphocytes a cytotoxic response against SEA-bound Raji cells. Target cell death is assayed colorimetrically with the CytoTox 96 cell lysis detection kit. In the experiments presented here, this bioassay was also able to detect heat-treated SEA, albeit with a slight compromise in sensitivity. This system detected SEA at picomolar concentrations. Because of the sensitivity of this assay, it is conceivable that it could be incorporated into current detection methods as a confirmatory test.
FDA Northeast Regional Laboratory, Microbiological Sciences Branch, Jamaica, New York 11433-1034, USA. thawrylu@ora.fda.gov
Timothy
T
Hawryluk
Irvin
I
Hirshfield
D001681:Biological Assay / Q000379:methods*; D003124:Colorimetry; D004768:Enterotoxins / Q000032:analysis* / Q000276:immunology; D005516:Food Microbiology; D007369:Interferon Inducers; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D013211:Staphylococcus aureus / Q000276:immunology*; D018089:Superantigens
D004768:Enterotoxins; D007369:Interferon Inducers; D011933:Reagent Kits, Diagnostic; D018089:Superantigens; C026066:enterotoxin A, Staphylococcal