IN-VITRO ASSAY OF STAPHYLOCOCCUS-AUREUS ENTEROTOXIN A ACTIVITY IN FOOD

Staphylococcus aureus enterotoxin A (SEA) is a leading cause of food p oisoning. The current test for functional activity of SEA requires mon keys or kittens. The major drawbacks of animal assays are lack of quan titation, poor reproducibility, low sensitivity and high cost. In this report we describe and evaluate an alternative assay using T-cell pro liferation to measure SEA activity in food. Human and rat lymphocytes proliferate in response to concentrations of SEA as low as 1 pg/ml, we ll below the pathogenic dose of 100 ng. This proliferation assay is hi ghly sensitive, quantitative, and simple. Nonradioactive assays of T-c ell proliferation were also suitable for detecting and measuring SEA, although with a 10-fold lower sensitivity. To evaluate the utility of this assay for food testing, four different food samples were mixed wi th SEA. In each sample, SEA was detected at a concentration of 1 ng/ml . Heat-inactivated SEA produced no detectable proliferation. These res ults demonstrate that an in vitro cell proliferation assay is an advan tageous alternative to existing animal assays for measuring SEA activi ty in food.