Development and application of DAS-ELISA for detection of staphylococcal enterotoxin A

Abstract:

[Objective] The research aimed to establish a rapid, sensitive and specific method for detection of staphylococcal enterotoxin A (SEA). [Methods] The soluble protein His-tagged SEA expressed in Escherichia coli was used as the immunogen to produce specific antibodies with high affinity. A double antibody sandwich ELISA (DAS-ELISA) was developed using anti-SEA monoclonal and polyclonal antibodies as capture antibody and detection antibody respectively. [Results] There was good linearity in the toxin range of 2?128 μg/L (y=1.102x-0.07, R2=0.994) with the detection limit at 1.89 μg/L. The assay showed no cross-reactivity with SEB, SEC2 or SED. The average recovery rates for SEA in milk ranged from 94%?114% with the variation coefficient less than 10%. In addition, the method was also successfully used to detect SEA-producing strains in culture filtrates. Of 46 Staphylococcus aureus isolates from aquatic products, 4.4% were SEA-producing, while 50.6% for 164 bovine mastitis isolates. [Conclusion] Therefore, the DAS-ELISA method was sensitive and specific, and could be used as a mean for monitoring food-borne SEA contamination.