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T cell Receptor Vβ9 in Method for Rapidly Quantifying Active Staphylococcal Enterotoxin Type-A without Live Animals

Staphylococcal food poisoning is a result of ingestion of Staphylococcal enterotoxins (SEs) produced by Staphylococcus aureus. Staphylococcal enterotoxin type A (SEA) is the predominant toxin produced by S. aureus strains isolated from food-poisoning outbreak cases. For public safety, assays to dete...

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Autores principales: Rasooly, Reuven, Do, Paula, He, Xiaohua, Hernlem, Bradley
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6669470/
https://www.ncbi.nlm.nih.gov/pubmed/31295829
http://dx.doi.org/10.3390/toxins11070399
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author Rasooly, Reuven
Do, Paula
He, Xiaohua
Hernlem, Bradley
author_facet Rasooly, Reuven
Do, Paula
He, Xiaohua
Hernlem, Bradley
author_sort Rasooly, Reuven
collection PubMed
description Staphylococcal food poisoning is a result of ingestion of Staphylococcal enterotoxins (SEs) produced by Staphylococcus aureus. Staphylococcal enterotoxin type A (SEA) is the predominant toxin produced by S. aureus strains isolated from food-poisoning outbreak cases. For public safety, assays to detect and quantify SEA ideally respond only to the active form of the toxin and this usually means employing disfavored live animal testing which suffers also from poor reproducibility and sensitivity. We developed a cell-based assay for SEA quantification in which biologically-active SEA is presented by Raji B-cells to CCRF-CEM T-cells resulting in internalization of Vβ9 within 2 hours with dose dependency over a 6-log range of SEA concentrations. This bioassay can discern biologically active SEA from heat-inactivated SEA and is specific to SEA with no cross reactivity to the homologically-similar SED or SEE. In this study, we terminated any ongoing biochemical reactions in accessory cells while retaining the morphology of the antigenic sites by using paraformaldehyde fixation and challenged the current model for mechanism of action of the SEA superantigen. We demonstrated for the first time that although fixed, dead accessory cells, having no metabolic functions to process the SEA superantigen into short peptide fragments for display on their cell surface, can instead present intact SEA to induce T-cell activation which leads to cytokine production. However, the level of cytokine secretion induced by intact SEA was statistically significantly lower than with viable accessory cells, which have the ability to internalize and process the SEA superantigen.
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spelling pubmed-66694702019-08-08 T cell Receptor Vβ9 in Method for Rapidly Quantifying Active Staphylococcal Enterotoxin Type-A without Live Animals Rasooly, Reuven Do, Paula He, Xiaohua Hernlem, Bradley Toxins (Basel) Article Staphylococcal food poisoning is a result of ingestion of Staphylococcal enterotoxins (SEs) produced by Staphylococcus aureus. Staphylococcal enterotoxin type A (SEA) is the predominant toxin produced by S. aureus strains isolated from food-poisoning outbreak cases. For public safety, assays to detect and quantify SEA ideally respond only to the active form of the toxin and this usually means employing disfavored live animal testing which suffers also from poor reproducibility and sensitivity. We developed a cell-based assay for SEA quantification in which biologically-active SEA is presented by Raji B-cells to CCRF-CEM T-cells resulting in internalization of Vβ9 within 2 hours with dose dependency over a 6-log range of SEA concentrations. This bioassay can discern biologically active SEA from heat-inactivated SEA and is specific to SEA with no cross reactivity to the homologically-similar SED or SEE. In this study, we terminated any ongoing biochemical reactions in accessory cells while retaining the morphology of the antigenic sites by using paraformaldehyde fixation and challenged the current model for mechanism of action of the SEA superantigen. We demonstrated for the first time that although fixed, dead accessory cells, having no metabolic functions to process the SEA superantigen into short peptide fragments for display on their cell surface, can instead present intact SEA to induce T-cell activation which leads to cytokine production. However, the level of cytokine secretion induced by intact SEA was statistically significantly lower than with viable accessory cells, which have the ability to internalize and process the SEA superantigen. MDPI 2019-07-10 /pmc/articles/PMC6669470/ /pubmed/31295829 http://dx.doi.org/10.3390/toxins11070399 Text en © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Rasooly, Reuven
Do, Paula
He, Xiaohua
Hernlem, Bradley
T cell Receptor Vβ9 in Method for Rapidly Quantifying Active Staphylococcal Enterotoxin Type-A without Live Animals
title T cell Receptor Vβ9 in Method for Rapidly Quantifying Active Staphylococcal Enterotoxin Type-A without Live Animals
title_full T cell Receptor Vβ9 in Method for Rapidly Quantifying Active Staphylococcal Enterotoxin Type-A without Live Animals
title_fullStr T cell Receptor Vβ9 in Method for Rapidly Quantifying Active Staphylococcal Enterotoxin Type-A without Live Animals
title_full_unstemmed T cell Receptor Vβ9 in Method for Rapidly Quantifying Active Staphylococcal Enterotoxin Type-A without Live Animals
title_short T cell Receptor Vβ9 in Method for Rapidly Quantifying Active Staphylococcal Enterotoxin Type-A without Live Animals
title_sort t cell receptor vβ9 in method for rapidly quantifying active staphylococcal enterotoxin type-a without live animals
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6669470/
https://www.ncbi.nlm.nih.gov/pubmed/31295829
http://dx.doi.org/10.3390/toxins11070399
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