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Rasooly R, Do P, He X, Hernlem B. Streptococcal pyrogenic exotoxin B is a superantigen that induces murine splenocyte proliferation and secretion of IL-2 and IFN-γ ex vivo. FEMS Microbiol Lett 2024; 371:fnae036. [PMID: 38806245 DOI: 10.1093/femsle/fnae036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 05/13/2024] [Accepted: 05/27/2024] [Indexed: 05/30/2024] Open
Abstract
Streptococcus pyogenes is a significant human pathogen, producing a range of virulence factors, including streptococcal pyrogenic exotoxin B (SpeB) that is associated with foodborne outbreaks. It was only known that this cysteine protease mediates cleavage of transmembrane proteins to permit bacterial penetration and is found in 25% of clinical isolates from streptococcal toxic shock syndrome patients with extreme inflammation. Its interaction with host and streptococcal proteins has been well characterized, but doubt remains about whether it constitutes a superantigen. In this study, for the first time it is shown that SpeB acts as a superantigen, similarly to other known superantigens such as staphylococcal enterotoxin A or streptococcal pyrogenic exotoxin type C, by inducing proliferation of murine splenocytes and cytokine secretion, primarily of interleukin-2 (IL-2), as shown by cytometric bead array analysis. IL-2 secretion was confirmed by enzyme-linked immunosorbent assay (ELISA) as well as secretion of interferon-γ. ELISA showed a dose-dependent relationship between SpeB concentration in splenocyte cells and IL-2 secretion levels, and it was shown that SpeB retains activity in milk pasteurized for 30 min at 63°C.
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Affiliation(s)
- Reuven Rasooly
- Foodborne Toxin Detection & Prevention Research Unit, Western Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710, United States
| | - Paula Do
- Foodborne Toxin Detection & Prevention Research Unit, Western Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710, United States
| | - Xiaohua He
- Foodborne Toxin Detection & Prevention Research Unit, Western Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710, United States
| | - Bradley Hernlem
- Foodborne Toxin Detection & Prevention Research Unit, Western Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710, United States
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Rasooly R, Do P, Hernlem B. T-cell receptor Vβ8 for detection of biologically active streptococcal pyrogenic exotoxin type C. J Dairy Sci 2023; 106:6723-6730. [PMID: 37210361 DOI: 10.3168/jds.2023-23286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 04/21/2023] [Indexed: 05/22/2023]
Abstract
Streptococcus pyogenes is an important human pathogen, commonly spread by airborne droplets but also by ingestion of contaminated food. Apart from causing infection, this pathogen produces 13 distinct types of streptococcal pyrogenic exotoxins (SPE). The current method for detection cannot distinguish between the biologically active form of SPE that has been reported to cause foodborne outbreaks and the inactivated toxin that poses no health risk. To measure the biological activity of SPE type C (SPE-C), one such toxin that was linked to foodborne outbreaks associated with milk and milk products, we developed a cell-based assay that can discern between biologically active and inactive SPE-C. To the best of our knowledge, this is the first showing that SPE-C activates T-cells expressing Vβ8. With this finding, we used a T-cell line natively expressing Vβ8 that was genetically engineered to also express the luciferase reporter gene under the regulation of nuclear factor of activated T-cells response element in combination with a B-cell line to present the recombinant SPE-C (rSPE-C) toxin via major histocompatibility complex (MHC) class II to the Vβ8 T-cell receptor (TCR) in an assay to detect and to discern between biologically active and inactive rSPE-C. By using this system, we demonstrated that SPE-C induced significant IL-2 secretion after 72 h and visible light emission after only 5 h, doubling by 24 h. We utilize this finding to assess the specificity of the assay and the effect of pasteurization on SPE-C activity. We observed no cross-reactivity with SPE-B and significant loss of SPE-C biological activity in spiked phosphate-buffered saline while SPE-C spiked into milk is heat stable. Once SPE-C has formed, it is infeasible to eliminate it from milk by thermal treatment.
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Affiliation(s)
- Reuven Rasooly
- Western Regional Research Center, Foodborne Toxin Detection and Prevention Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710.
| | - Paula Do
- Western Regional Research Center, Foodborne Toxin Detection and Prevention Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710
| | - Bradley Hernlem
- Western Regional Research Center, Foodborne Toxin Detection and Prevention Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710
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Rasooly R, Do P, Hernlem B. Ex Vivo and In Vitro Methods for Detection of Bioactive Staphylococcal Enterotoxins. Methods Mol Biol 2022; 2393:237-255. [PMID: 34837183 DOI: 10.1007/978-1-0716-1803-5_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Staphylococcus aureus is a major bacterial cause of clinical infections and foodborne illnesses.Through the synthesis of a group of Staphylococcal enterotoxins (SEs), gastroenteritis occurs and the SEs function as superantigens to massively activate T cells. The ability to rapidly detect and quantify SEs is imperative in order to learn the causes of staphylococcal outbreaks and to stop similar outbreaks in the future. Also, the ability to discern active toxin is essential for development of food treatment and processing methods. Here, we discuss the various methodologies for detection and analysis of SEs.
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Affiliation(s)
- Reuven Rasooly
- Western Regional Research Center, Foodborne Toxin Detection & Prevention Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA, USA.
| | - Paula Do
- Western Regional Research Center, Foodborne Toxin Detection & Prevention Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA, USA
| | - Bradley Hernlem
- Western Regional Research Center, Foodborne Toxin Detection & Prevention Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA, USA
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Rasooly R, Do P, He X, Hernlem B. Human Leukemia T-Cell Lines as Alternatives to Animal Use for Detecting Biologically Active Staphylococcal Enterotoxin Type B. Toxins (Basel) 2021; 13:toxins13050300. [PMID: 33922450 PMCID: PMC8145393 DOI: 10.3390/toxins13050300] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 04/19/2021] [Accepted: 04/21/2021] [Indexed: 11/17/2022] Open
Abstract
Staphylococcal enterotoxin type B (SEB) is associated with food poisoning. Current methods for the detection of biologically active SEB rely upon its ability to cause emesis when administered to live kittens or monkeys. This technique suffers from poor reproducibility and low sensitivity and is ethically disfavored over concerns for the welfare of laboratory animals. The data presented here show the first successful implementation of an alternative method to live animal testing that utilizes SEB super-antigenic activity to induce cytokine production for specific novel cell-based assays for quantifiable detection of active SEB. Rather than using or sacrificing live animals, we found that SEB can bind to the major histocompatibility complex (MHC) class II molecules on Raji B-cells. We presented this SEB–MHC class II complex to specific Vβ5.3 regions of the human T-cell line HPB-ALL, which led to a dose-dependent secretion of IL-2 that is capable of being quantified and can further detect 10 pg/mL of SEB. This new assay is 100,000 times more sensitive than the ex vivo murine splenocyte method that achieved a detection limit of 1 µg/mL. The data presented here also demonstrate that SEB induced proliferation in a dose-dependent manner for cells obtained by three different selection methods: by splenocyte cells containing 22% of CD4+ T-cells, by CD4+ T-cells enriched to >90% purity by negative selection methods, and by CD4+ T-cells enriched to >95% purity by positive selection methods. The highly enriched and positively isolated CD4+ T-cells with the lowest concentration of antigen-presenting cells (APC) (below 5%) provided higher cell proliferation than the splenocyte cells containing the highest concentration of APC cells.
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T cell Receptor Vβ9 in Method for Rapidly Quantifying Active Staphylococcal Enterotoxin Type-A without Live Animals. Toxins (Basel) 2019; 11:toxins11070399. [PMID: 31295829 PMCID: PMC6669470 DOI: 10.3390/toxins11070399] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 07/05/2019] [Accepted: 07/07/2019] [Indexed: 01/24/2023] Open
Abstract
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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Isolation, Identification, and Characterization of a Novel Bacteriocin Produced by Brevibacillus laterosporus DS-3 Against Methicillin-Resistant Staphylococcus aureus (MRSA). Int J Pept Res Ther 2019. [DOI: 10.1007/s10989-019-09878-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Purification, Characterization, and Mode of Action of Pentocin JL-1, a Novel Bacteriocin Isolated from Lactobacillus pentosus, against Drug-Resistant Staphylococcus aureus. BIOMED RESEARCH INTERNATIONAL 2017; 2017:7657190. [PMID: 29333451 PMCID: PMC5733122 DOI: 10.1155/2017/7657190] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 09/21/2017] [Accepted: 10/18/2017] [Indexed: 12/16/2022]
Abstract
Staphylococcus aureus and its drug-resistant strains, which threaten public health and food safety, are in need of effective control by biopreservatives. A novel bacteriocin, pentocin JL-1, produced by Lactobacillus pentosus that was isolated from the intestinal tract of Chiloscyllium punctatum, was purified by a four-step chromatographic process. Mass spectrometry based on MALDI-TOF indicated that pentocin JL-1 has a molecular mass of 2987.23 Da. Only six of the twenty-five amino acids could be identified by Edman degradation. This bacteriocin is thermostable and tolerates a pH range of 5–7. Also, it is sensitive to proteinase K, trypsin, pepsin, and alkaline protease. This bacteriocin has a broad inhibitory spectrum against both Gram-positive and Gram-negative strains and in particular is effective against multidrug-resistant S. aureus. Additionally, we showed that the cell membrane is the target of pentocin JL-1 against methicillin-resistant S. aureus (MRSA), causing a loss of proton motive force. Furthermore, pentocin JL-1 has a drastic impact on the structure and integrity of MRSA cells. These results suggest that pentocin JL-1 has potential as a biopreservative in the food industry.
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Rasooly R, Do PM, Hernlem BJ. Rapid Cell-Based Assay for Detection and Quantification of Active Staphylococcal Enterotoxin Type D. J Food Sci 2017; 82:718-723. [PMID: 28135403 DOI: 10.1111/1750-3841.13634] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 11/28/2016] [Accepted: 12/29/2016] [Indexed: 11/29/2022]
Abstract
Food poisoning by Staphylococcus aureus is a result of ingestion of Staphylococcal enterotoxins (SEs) produced by this bacterium and is a major source of foodborne illness. Staphylococcal enterotoxin D (SED) is one of the predominant enterotoxins recovered in Staphylococcal food poisoning incidences, including a recent outbreak in Guam affecting 300 children. Current immunology methods for SED detection cannot distinguish between the biologically active form of the toxin, which poses a threat, from the inactive form, which poses no threat. In vivo bioassays that measure emetic activity in kitten and monkeys have been used, but these methods rely upon expensive procedures using live animals and raising ethical concerns. A rapid (5 h) quantitative bioluminescence assay, using a genetically engineered T-cell Jurkat cell line expressing luciferase under regulation of nuclear factor of activated T cells response elements, in combination with the lymphoblastoid B-cell line Raji for antigen presentation, was developed. In this assay, the detection limit of biologically active SED is 100 ng/mL, which is 10 times more sensitive than the splenocyte proliferation assay, and 105 times more sensitive than monkey or kitten bioassay. Pasteurization or repeated freeze-thaw cycles had no effect on SED activity, but reduction in SED activity was shown with heat treatment at 100°C for 5 min. It was also shown that milk exhibits a protective effect on SED. This bioluminescence assay may also be used to rapidly evaluate antibodies to SED for potential therapeutic application as a measurement of neutralizing biological effects of SED.
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Affiliation(s)
- Reuven Rasooly
- Western Regional Research Center, Foodborne Toxin Detection and Prevention Research Unit, Agricultural Research Service, USDA, Albany, CA, U.S.A
| | - Paula M Do
- Western Regional Research Center, Foodborne Toxin Detection and Prevention Research Unit, Agricultural Research Service, USDA, Albany, CA, U.S.A
| | - Bradley J Hernlem
- Western Regional Research Center, Foodborne Toxin Detection and Prevention Research Unit, Agricultural Research Service, USDA, Albany, CA, U.S.A
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Wang K, Wu D, Chen Z, Zhang X, Yang X, Yang CJ, Lan X. Inhibition of the superantigenic activities of Staphylococcal enterotoxin A by an aptamer antagonist. Toxicon 2016; 119:21-7. [DOI: 10.1016/j.toxicon.2016.05.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Revised: 04/29/2016] [Accepted: 05/10/2016] [Indexed: 12/30/2022]
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Zhao X, Shi C, Meng R, Liu Z, Huang Y, Zhao Z, Guo N. Effect of nisin and perilla oil combination against Listeria monocytogenes and Staphylococcus aureus in milk. Journal of Food Science and Technology 2016; 53:2644-53. [PMID: 27478220 DOI: 10.1007/s13197-016-2236-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 01/20/2016] [Accepted: 04/12/2016] [Indexed: 11/29/2022]
Abstract
In the present study, in vitro interaction of nisin and perilla oil (PO) against 20 food-borne isolates of L. monocytogenes and S. aureus were assessed using a checkerboard microdilution method. Synergism was observed in tested strains with the fractional inhibitory concentration indexs (FICIs) ranges from 0.125-0.25 and 0.19-0.375, respectively. Scanning electron microscopy was carried out to investigate the effect of nisin and PO on the integrity of cell wall and membrane of L. monocytogenes and S. aureus. The results showed that nisin and PO were more effective in damaging cell wall and membrane in combination.
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Affiliation(s)
- Xingchen Zhao
- Department of Food Quality and Safety, College of Food Science and Engineering, Jilin University, Changchun, 130062 China
| | - Ce Shi
- Department of Food Quality and Safety, College of Food Science and Engineering, Jilin University, Changchun, 130062 China
| | - Rizeng Meng
- Jilin Entry-Exit Inspection and Quarantine Bureau, Changchun, 130062 China
| | - Zonghui Liu
- Department of Food Quality and Safety, College of Food Science and Engineering, Jilin University, Changchun, 130062 China
| | - Yanjun Huang
- Department of Food Quality and Safety, College of Food Science and Engineering, Jilin University, Changchun, 130062 China
| | - Ziwen Zhao
- Department of Food Quality and Safety, College of Food Science and Engineering, Jilin University, Changchun, 130062 China
| | - Na Guo
- Department of Food Quality and Safety, College of Food Science and Engineering, Jilin University, Changchun, 130062 China
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Rasooly R, Do P, Hernlem B. Sensitive, Rapid, Quantitative and in Vitro Method for the Detection of Biologically Active Staphylococcal Enterotoxin Type E. Toxins (Basel) 2016; 8:toxins8050150. [PMID: 27187474 PMCID: PMC4885065 DOI: 10.3390/toxins8050150] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 05/06/2016] [Accepted: 05/09/2016] [Indexed: 11/24/2022] Open
Abstract
Staphylococcus aureus is a major bacterial cause of clinical infections and foodborne illnesses through its production of a group of enterotoxins (SEs) which cause gastroenteritis and also function as superantigens to massively activate T cells. In the present study, we tested Staphylococcal enterotoxin type E (SEE), which was detected in 17 of the 38 suspected staphylococcal food poisoning incidents in a British study and was the causative agent in outbreaks in France, UK and USA. The current method for detection of enterotoxin activity is an in vivo monkey or kitten bioassay; however, this expensive procedure has low sensitivity and poor reproducibility, requires many animals, is impractical to test on a large number of samples, and raises ethical concerns with regard to the use of experimental animals. The purpose of this study is to develop rapid sensitive and quantitative bioassays for detection of active SEE. We apply a genetically engineered T cell-line expressing the luciferase reporter gene under the regulation of nuclear factor of activated T-cells response element (NFAT-RE), combined with a Raji B-cell line that presents the SEE-MHC (major histocompatibility complex) class II to the engineered T cell line. Exposure of the above mixed culture to SEE induces differential expression of the luciferase gene and bioluminescence is read out in a dose dependent manner over a 6-log range. The limit of detection of biologically active SEE is 1 fg/mL which is 109 times more sensitive than the monkey and kitten bioassay.
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Affiliation(s)
- Reuven Rasooly
- Western Regional Research Center, Foodborne Toxin Detection & Prevention Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710, USA.
| | - Paula Do
- Western Regional Research Center, Foodborne Toxin Detection & Prevention Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710, USA.
| | - Bradley Hernlem
- 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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Ménoret A, Svedova J, Behl B, Vella AT. Trace Levels of Staphylococcal Enterotoxin Bioactivity Are Concealed in a Mucosal Niche during Pulmonary Inflammation. PLoS One 2015; 10:e0141548. [PMID: 26509442 PMCID: PMC4625020 DOI: 10.1371/journal.pone.0141548] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 10/10/2015] [Indexed: 02/01/2023] Open
Abstract
Pathogen and cellular by-products released during infection or trauma are critical for initiating mucosal inflammation. The localization of these factors, their bioactivity and natural countermeasures remain unclear. This concept was studied in mice undergoing pulmonary inflammation after Staphylococcal enterotoxin A (SEA) inhalation. Highly purified bronchoalveolar lavage fluid (BALF) fractions obtained by sequential chromatography were screened for bioactivity and subjected to mass spectrometry. The Inflammatory and inhibitory potentials of the identified proteins were measured using T cells assays. A potent pro-inflammatory factor was detected in BALF, and we hypothesized SEA could be recovered with its biological activity. Highly purified BALF fractions with bioactivity were subjected to mass spectrometry. SEA was the only identified protein with known inflammatory potential, and unexpectedly, it co-purified with immunosuppressive proteins. Among them was lactoferrin, which inhibited SEA and anti-CD3/-CD28 stimulation by promoting T cell death and reducing TNF synthesis. Higher doses of lactoferrin were required to inhibit effector compared to resting T cells. Inhibition relied on the continual presence of lactoferrin rather than a programming event. The data show a fraction of bioactive SEA resided in a mucosal niche within BALF even after the initiation of inflammation. These results may have clinical value in human diagnostic since traces levels of SEA can be detected using a sensitive bioassay, and may help pinpoint potential mediators of lung inflammation when molecular approaches fail.
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Affiliation(s)
- Antoine Ménoret
- Department of Immunology MC3710. University of Connecticut Health, 263 Farmington Avenue, Farmington, CT 06032, United States of America
| | - Julia Svedova
- Department of Immunology MC3710. University of Connecticut Health, 263 Farmington Avenue, Farmington, CT 06032, United States of America
| | - Bharat Behl
- Department of Immunology MC3710. University of Connecticut Health, 263 Farmington Avenue, Farmington, CT 06032, United States of America
| | - Anthony T. Vella
- Department of Immunology MC3710. University of Connecticut Health, 263 Farmington Avenue, Farmington, CT 06032, United States of America
- * E-mail:
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Rasooly R, Balsam J, Hernlem BJ, Rasooly A. Sensitive detection of active Shiga toxin using low cost CCD based optical detector. Biosens Bioelectron 2015; 68:705-711. [PMID: 25677808 DOI: 10.1016/j.bios.2015.01.065] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 01/26/2015] [Accepted: 01/28/2015] [Indexed: 01/22/2023]
Abstract
To reduce the sources and incidence of food-borne illness there is a need to develop affordable, sensitive devices for detection of active toxins, such as Shiga toxin type 2 (Stx2). Currently the widely used methods for measuring Shiga toxin are immunoassay that cannot distinguish between the active form of the toxin, which poses a threat to life, to the inactive form which can bind to antibodies but show no toxicity. In this work, we determine toxin activity based on Shiga toxin inhibition of green fluorescent protein (GFP) combined with low cost charge-coupled device (CCD) fluorescence detection, which is more clinically relevant than immunoassay. For assay detection, a simple low cost fluorescence detection system was constructed using a CCD camera and light emitting diode (LED) excitation source, to measure GFP expression. The system was evaluated and compared to a commercial fluorometer using photomultiplier detection for detecting active Stx2 in the range 100 ng/mL-0.01 pg/mL. The result shows that there is a negative linear relationship between Stx2 concentrations and luminous intensity of GFP, imaged by the CCD camera (R(2)=0.85) or fluorometer (R(2)=0.86). The low cost (∼$300) CCD camera is capable of detecting Shiga toxin activity at comparable levels as a more expensive (∼$30,000) fluorometer. These results demonstrate the utility and the potential of low cost detectors for toxin activity; this approach may increase the availability of foodborne bacterial toxin diagnostics in regions where there are limited resources and could be readily adapted to the detection of other food-borne toxins.
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Affiliation(s)
- Reuven Rasooly
- Western Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Albany, CA, United States.
| | - Josh Balsam
- Division of Biology, Office of Science and Engineering, FDA, Silver Spring, MD 20993, United States; University of Maryland, College Park, MD 20742, United States
| | - Bradley J Hernlem
- Western Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Albany, CA, United States
| | - Avraham Rasooly
- Division of Biology, Office of Science and Engineering, FDA, Silver Spring, MD 20993, United States; Office of Cancer Complementary and Alternative Medicine, National Cancer Institute, Rockville, MD 20850, United States
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Zhu X, Shen L, Liu J, Zhang C, Gu Q. Purification of a Bacteriocin from Lactobacillus plantarum ZJ217 Active Against Methicillin-Resistant Staphylococcus aureus. INTERNATIONAL JOURNAL OF FOOD ENGINEERING 2015. [DOI: 10.1515/ijfe-2014-0176] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Plantaricin ZJ217 was continually purified by XAD 1180, cation exchange chromatography, gel chromatography, and high performance liquid chromatography (HPLC) system. The peptide functioned as bactericidal, but did not lead to lysis of cells. Considering the potassium efflux experiment, pores may be formed in the surface of cell membrane. Fifteen of twenty amino acids identified by Edman degradation indicated that it may be a novel bacteriocin as no bacteriocin shared similar sequences. This bacteriocin exhibited strong heat stability (121°C, 30 min) and pH stability (pH 2.0–6.0). It was sensitive to proteinase K, trypsin, papain, and pepsin. This bacteriocin inhibited growth of methicillin-resistant Staphylococcus aureus (MRSA) and other bacteria.
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Rasooly R, Hernlem BJ. Quantitative analysis of staphylococcus enterotoxin A by differential expression of IFN-γ in splenocyte and CD4⁺ T-cells. SENSORS 2014; 14:8869-76. [PMID: 24854207 PMCID: PMC4063072 DOI: 10.3390/s140508869] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 05/15/2014] [Accepted: 05/15/2014] [Indexed: 11/21/2022]
Abstract
Staphylococcus aureus is an important bacterial pathogen that produces a range of Staphylococcal Enterotoxins (SEs) which cause gastroenteritis and superantigen activation of T cells, the mechanism of which is not well understood. The ability to rapidly detect and quantify SEs is very important in order to learn the causes of staphylococcal outbreaks and to stop similar outbreaks in the future. Enzyme-linked immunosorbent assays (ELISAs) have been developed for detection of several SEs. However, these immunological methods cannot distinguish between active and inactive toxin. It is known that interferon-gamma (IFN-γ) expressed in response to stimulation by SEs contributes significantly to the pathogenesis of S. aureus infection. Nonetheless, the cellular source of IFN-γ is still unclear and the contributions of the specific splenocyte types. In our effort to understand the immunologic response to Staphylococcal Enterotoxin A (SEA) exposure, we studied IFN-γ production in mouse splenocytes. We demonstrated that short term ex vivo exposure of splenocytes or primary naïve CD4+ T-cells to biologically active SEA induces differential expression of IFN-γ mRNA in a time and dose dependent manner and the expression levels reflect the levels of IFN-γ secreted protein. Positive isolated CD4+ T-cells accounted for only 10% of IFN-γ production. We also demonstrate that expression of IFN-γ can be used for rapid quantitative analysis of active SEA with a detection limit of 1 ng/mL.
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Affiliation(s)
- Reuven Rasooly
- Western Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Albany, CA 94710, USA.
| | - Bradley J Hernlem
- Western Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Albany, CA 94710, USA.
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Zhu X, Zhao Y, Sun Y, Gu Q. Purification and characterisation of plantaricin ZJ008, a novel bacteriocin against Staphylococcus spp. from Lactobacillus plantarum ZJ008. Food Chem 2014; 165:216-23. [PMID: 25038669 DOI: 10.1016/j.foodchem.2014.05.034] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Revised: 04/14/2014] [Accepted: 05/11/2014] [Indexed: 10/25/2022]
Abstract
A novel bacteriocin, plantaricin ZJ008 produced by Lactobacillus plantarum ZJ008 isolated from fresh milk, was purified by XAD 2, cation exchange chromatograph, gel chromatograph, and RP-HPLC. Mass spectrometry based on MALDI-TOF indicated that the bacteriocin had a molecular of 1334.77 Da. Only five of twenty amino acids could be identified by Edman degradation. This bacteriocin was highly thermostable (121°C, 30 min) and exhibited narrow pH stability (pH 4.0-5.0). It was sensitive to α-Chymotrypsin, trypsin, papain, and pepsin. However it still had 80% of activity after treatment by proteinase K. The action mode of this peptide functioned as bactericidal, but it did not lead to lysis of cells. This bacteriocin exhibited broad-spectrum antimicrobial activity against tested Gram-positive and Gram-negative bacteria, especially Staphylococcus spp. These results suggested that this bacteriocin appears potentially very useful to control and inhibit Staphylococcus spp. in the food industry.
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Affiliation(s)
- Xuan Zhu
- Zhejiang Gongshang University, Key Laboratory for Food Microbial Technology of Zhejiang Province, Hangzhou, Zhejiang Province, China
| | - Yizhen Zhao
- Zhejiang Gongshang University, Key Laboratory for Food Microbial Technology of Zhejiang Province, Hangzhou, Zhejiang Province, China
| | - Yalian Sun
- Zhejiang Gongshang University, Key Laboratory for Food Microbial Technology of Zhejiang Province, Hangzhou, Zhejiang Province, China
| | - Qing Gu
- Zhejiang Gongshang University, Key Laboratory for Food Microbial Technology of Zhejiang Province, Hangzhou, Zhejiang Province, China.
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Zhang C, Liu Z, Li Y, Li Q, Song C, Xu Z, Zhang Y, Zhang Y, Ma Y, Sun Y, Chen L, Fang L, Yang A, Yang K, Jin B. High sensitivity chemiluminescence enzyme immunoassay for detecting staphylococcal enterotoxin A in multi-matrices. Anal Chim Acta 2013; 796:14-9. [DOI: 10.1016/j.aca.2013.07.044] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 07/04/2013] [Accepted: 07/16/2013] [Indexed: 10/26/2022]
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18
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Rasooly R, Hernlem B, Friedman M. Low levels of aflatoxin B1, ricin, and milk enhance recombinant protein production in mammalian cells. PLoS One 2013; 8:e71682. [PMID: 23940780 PMCID: PMC3733960 DOI: 10.1371/journal.pone.0071682] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 07/09/2013] [Indexed: 11/18/2022] Open
Abstract
Gene expression in transduced mammalian cells correlates with virus titer, but high doses of vector for gene therapy leads to toxicity in humans and in animals. Changing the optimal tissue culture medium by adding low levels of environmental stressors, such as 1 µM of the fungal toxin aflatoxin B1 (AFB1), 1 ng of the castor bean protein toxin ricin, or 1% reconstituted milk, enhances transcription and increases production of proteins in transduced mammalian cells as demonstrated by production of the following three recombinant proteins: firefly luciferase, β-galactosidase, and green fluorescent protein (GFP). Higher concentrations of the stress-producing substances damage the cells beyond recovery, resulting in inhibited gene expression and cell death. We also evaluated the effect of the stressor substances on the enhanced infectivity of virus. The presented findings extend methods for large-scale transient recombinant protein production in mammalian cells and suggest that it may be possible to reduce the cytotoxicity of the adenovirus by reducing the virus titer without adversely affecting gene expression levels.
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Affiliation(s)
- Reuven Rasooly
- Foodborne Contaminants, Agricultural Research Service, United State Department of Agriculture, Albany, California, United State of America.
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19
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Recognition and enrichment specificity of Fe3O4 magnetic nanoparticles surface modified by chitosan and Staphylococcus aureus enterotoxins A antiserum. Colloids Surf B Biointerfaces 2013. [DOI: 10.1016/j.colsurfb.2012.10.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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20
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Rasooly R, Hernlem BJ. CD154 as a potential early molecular biomarker for rapid quantification analysis of active Staphylococcus enterotoxin A. ACTA ACUST UNITED AC 2012; 64:169-74. [PMID: 22067024 DOI: 10.1111/j.1574-695x.2011.00874.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Staphylococcus aureus is a major bacterial pathogen producing a group of 21 enterotoxins (SEs). These enterotoxins have two separate but related biological activities. They cause gastroenteritis, and they function as superantigens that activate large numbers of T cells. In the current study, we demonstrate that short-term ex vivo exposure of primary naïve CD4(+) T-cells to SEA induces differential expression of the T cell surface receptor CD154 in a time- and dose-dependent manner. In addition, we show that SEA induces higher CD154 protein expression and higher splenocyte cell proliferation compared with SEB. We also demonstrate that expression of CD154 can be used for rapid detection of active SEA in milk.
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Affiliation(s)
- Reuven Rasooly
- Western Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Albany, CA 94710, USA.
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21
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Sospedra I, Marín R, Mañes J, Soriano JM. Rapid whole protein quantification of staphylococcal enterotoxin B by liquid chromatography. Food Chem 2012. [DOI: 10.1016/j.foodchem.2011.12.083] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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22
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TNF as biomarker for rapid quantification of active Staphylococcus enterotoxin A in food. SENSORS 2012; 12:5978-85. [PMID: 22778626 PMCID: PMC3386725 DOI: 10.3390/s120505978] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2012] [Revised: 04/19/2012] [Accepted: 05/03/2012] [Indexed: 11/17/2022]
Abstract
Staphylococcus aureus is a major bacterial pathogen which causes clinical infections and food poisoning. This bacterium produces a group of twenty-one enterotoxins (SEs). These enterotoxins have two separate but related biological activities. They cause gastroenteritis and function as superantigens that activate large numbers of T cells. The current method for detection of enterotoxins activity is an in vivo monkey or kitten bioassay; however, this method is not practical to test on a large number of samples. Several immunological assays have been developed however, but these assays cannot distinguish between active toxin which causes food poisoning and inactive toxin, which can bind antibody, but shows no toxicity. The current study demonstrates that short term ex vivo exposure of primary naïve CD4(+) T-cells or splenocytes to SEA induces differential expression and secretion of tumor necrosis factor (TNF) protein. We used immunomagnetic beads coated with anti-SEA antibody to specifically isolate SEA from food. After the eluted toxin was added to the cells SEA biological activity was measured by quantifying TNF protein expression or secretion.
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23
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Friedman M, Rasooly R. Response to Dr. Archer's Letter to the Editor. J Food Sci 2012. [DOI: 10.1111/j.1750-3841.2011.02568_2.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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24
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Archer DL. Comments on Dr. Friedman's Response. J Food Sci 2012. [DOI: 10.1111/j.1750-3841.2011.02568_3.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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25
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Sospedra I, Soler C, Mañes J, Soriano JM. Analysis of staphylococcal enterotoxin A in milk by matrix-assisted laser desorption/ionization-time of flight mass spectrometry. Anal Bioanal Chem 2011; 400:1525-31. [PMID: 21442364 DOI: 10.1007/s00216-011-4906-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 03/11/2011] [Accepted: 03/12/2011] [Indexed: 11/30/2022]
Abstract
Staphylococcal enterotoxin A (SEA) is an exotoxin excreted mainly by Staphylococcus aureus and nowadays is the most prevalent compound in staphylococcal food poisoning worldwide. SEA is highly heat-resistant, and usual cooking times and temperatures are unlikely to completely inactivate it. A procedure for extraction of this toxin based on protein precipitation with a mixture of dichloromethane and acidified water was used before SDS-PAGE separation of soluble proteins. Finally, bands of interest were excised from the gel and in-gel enzymatic digestion was done. SEA from pasteurized milk was detected with matrix-assisted laser-desorption/ionization-time of flight (MALDI-TOF) mass spectrometry. Nineteen peptides (range 800-2400 Da) were identified as products of trypsin cleavage of the SEA standard with a score of 204 and 73% coverage of the protein sequence, whereas thirteen peptides were revealed for SEA extracted from milk with a score of 148 and 58% sequence coverage obtained. This procedure has been applied successfully for identification of SEA in milk.
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Affiliation(s)
- Isabel Sospedra
- Department of Preventive Medicine and Public Health, Faculty of Pharmacy, University of Valencia, Av. Vicent Andrés Estellés s/n, 46100 Burjassot, Spain.
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26
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Rasooly R, Do PM, Levin CE, Friedman M. Inhibition of Shiga Toxin 2 (Stx2) in Apple Juices and its Resistance to Pasteurization. J Food Sci 2010; 75:M296-301. [DOI: 10.1111/j.1750-3841.2010.01615.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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27
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Rasooly R, Do PM, Friedman M. Inhibition of biological activity of staphylococcal enterotoxin A (SEA) by apple juice and apple polyphenols. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:5421-5426. [PMID: 20402509 DOI: 10.1021/jf904021b] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The foodborne pathogen Staphylococcus aureus produces the virulent staphylococcal enterotoxin A (SEA), a single-chain protein that consists of 233 amino acid residues with a molecular weight of 27 078 Da. SEA is a superantigen that is reported to contribute to animal (mastitis) and human (emesis, diarrhea, atopic dermatitis, arthritis, and toxic shock) syndromes. Changes of the native structural integrity may inactivate the toxin by preventing molecular interaction with cell membrane receptor sites of their host cells. In the present study, we evaluated the ability of one commercial and two freshly prepared apple juices and a commercial apple polyphenol preparation (Apple Poly) to inhibit the biological activity of SEA. Dilutions of freshly prepared apple juices and Apple Poly inhibited the biological activity of SEA without any significant cytotoxic effect on the spleen cells. Additional studies with antibody-coated immunomagnetic beads bearing specific antibodies against the toxin revealed that SEA added to apple juice appears to be largely irreversibly bound to the juice constituents. The results suggest that food-compatible and safe anti-toxin phenolic compounds can be used to inactivate SEA in vitro and possibly also in vivo, even after induction of T-cell proliferation by long-term exposure to SEA. The significance of the results for microbial food safety and human health is discussed.
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Affiliation(s)
- Reuven Rasooly
- Western Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Albany, California 94710, USA.
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