In Vitro Detection of Biologically Active Staphylococcal Enterotoxins Type B and C1 as an Alternative to In Vivo Testing

Staphylococcus aureus is a major bacterial pathogen that can cause clinical infections and foodborne illnesses through the production of 25 exotoxin types. The most frequently implicated toxins in food poisoning outbreaks are Staphylococcal enterotoxins type A–E (SEA-SEE), which are the first enterotoxins discovered. While in vitro detection methods are available to identify the presence of enterotoxins, they cannot distinguish between biologically active and inactive forms of the toxins. Detection of biologically active enterotoxins currently relies on in vivo testing, using the emetic response in kittens or monkeys. Here, we show the development of an in vitro assay to detect the active forms of SEB, a potential biological warfare agent and leading cause of food poisoning, and SEC1, a frequent cause of staphylococcal food poisoning. The novel assay involves the implementation of a genetically engineered Jurkat T-cell line expressing TCR Vβ3, resulting in a dose response of IL-2 production when exposed to active toxin. We also show that at a concentration of 100 ng/mL, the biological activity of SEB is significantly decreased at temperatures over 70 °C, while pasteurization at 63 °C only slightly reduces the biological activity of the toxin. Our studies provide an alternative method to animal testing to determine the presence of active toxins and provide possible inactivation methods of the toxins.