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Article

Alternative to Animal Use for Detecting Biologically Active Staphylococcal Enterotoxin Type A

Western Regional Research Center, Foodborne Toxin Detection & Prevention Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710, USA
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Toxins 2018, 10(12), 540; https://doi.org/10.3390/toxins10120540
Received: 16 November 2018 / Revised: 10 December 2018 / Accepted: 13 December 2018 / Published: 15 December 2018
(This article belongs to the Section Bacterial Toxins)
Staphylococcal enterotoxins (SEs) are a food safety concern. Existing methods for biologically active SE detection rely on the emetic response in live kittens or monkeys. This method suffers from low sensitivity, poor reproducibility, and causes ethical concerns regarding the use of experimental animals. The Lautenberg Chemical Safety Act encourages the development and adoption of alternatives to testing on animals for chemical toxicity methodologies. In this study, we utilized the superantigenic effect of SE type A (SEA) and used an ex vivo bioassay as an alternative to live animal testing. We found that interleukin-2 (IL-2) secreted by splenocyte can be utilized for quantifiable detection of SEA in food products. To avoid food matrix interference and attenuation of signal, we separated SEA from spiked food products by employing immunomagnetic beads that were coated with an anti-SEA antibody. This ex vivo method has achieved the detection of 1 ng mL−1 of SEA, which is 107 times more sensitive than the existing live animal testing methods. However, this ex vivo bioassay requires sacrificing of mice. To overcome this limitation, we established a cell based in vitro assay using CCRF-CEM, a human CD4+ T-cell line, for the quantitative detection of SEA. Incubation of SEA with CCRF-CEM human T-cells and Raji cells led to quantifiable and dose dependent secretion of IL-2. This novel cell-based assay is highly specific to biologically active SEA, compared with the related SE toxin subtypes B, D, and E or heat inactivated SEA, which produce no secretion of IL-2. This is the first demonstration of an alternative assay that completely eliminates the use of animals for quantitative detection of active SEA. View Full-Text
Keywords: staphylococcal enterotoxin type A; T-cell line; B-cell line; splenocyte staphylococcal enterotoxin type A; T-cell line; B-cell line; splenocyte
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MDPI and ACS Style

Rasooly, R.; Do, P.; He, X.; Hernlem, B. Alternative to Animal Use for Detecting Biologically Active Staphylococcal Enterotoxin Type A. Toxins 2018, 10, 540. https://doi.org/10.3390/toxins10120540

AMA Style

Rasooly R, Do P, He X, Hernlem B. Alternative to Animal Use for Detecting Biologically Active Staphylococcal Enterotoxin Type A. Toxins. 2018; 10(12):540. https://doi.org/10.3390/toxins10120540

Chicago/Turabian Style

Rasooly, Reuven, Paula Do, Xiaohua He, and Bradley Hernlem. 2018. "Alternative to Animal Use for Detecting Biologically Active Staphylococcal Enterotoxin Type A" Toxins 10, no. 12: 540. https://doi.org/10.3390/toxins10120540

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