Rapid Cell-Based Assay for Detection and Quantification of Active Staphylococcal Enterotoxin Type D

Area of Science:

• Food Science
• Immunology
• Microbiology

Background:

• Staphylococcus aureus food poisoning is caused by Staphylococcal enterotoxins (SEs).
• Staphylococcal enterotoxin D (SED) is a prevalent toxin in food poisoning outbreaks.
• Existing detection methods cannot differentiate active from inactive SED, and animal bioassays raise ethical concerns.

Purpose of the Study:

• To develop a rapid, sensitive, and ethical assay for detecting biologically active SED.
• To evaluate the stability of SED under various conditions.
• To assess the potential of the assay for evaluating therapeutic antibodies.

Main Methods:

• A quantitative bioluminescence assay was developed using engineered Jurkat T-cells and Raji B-cells.
• The assay measures luciferase activity, indicating the presence of biologically active SED.
• SED activity was tested after heat treatment, pasteurization, freeze-thaw cycles, and in the presence of milk.

Main Results:

• The assay detected biologically active SED with a limit of 100 ng/mL, significantly more sensitive than other methods.
• Pasteurization and freeze-thaw cycles did not affect SED activity.
• Heat treatment at 100°C for 5 min reduced SED activity, and milk showed a protective effect.

Conclusions:

• The developed bioluminescence assay offers a rapid and sensitive method for detecting biologically active SED.
• This assay provides a valuable tool for food safety and can be used to assess neutralizing antibodies for therapeutic applications.