Abrin Toxin Paradoxically Increases Protein Synthesis in Stimulated CD4 T-Cells While Decreasing Protein Synthesis in Kidney Cells.

Abrin, a toxin of the rosary pea plant (), has been implicated as causing an autoimmune demyelinating disease in humans, but the exact mechanisms responsible for the induction of these demyelinating conditions are still unknown. Certain superantigen microbial toxins such as Staphylococcus enterotoxin type A, type D, type E or streptococcal pyrogenic exotoxin type C also lead to various diseases including autoimmune disorders of the nervous system. Here, the effect of abrin toxin on the immune reaction was studied in human CD4 T-cell lines, and its inhibition of protein synthesis in kidney cells.

Streptococcal pyrogenic exotoxin B is a superantigen that induces murine splenocyte proliferation and secretion of IL-2 and IFN-γ ex vivo.

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.

A novel Shiga toxin 2a neutralizing antibody therapeutic with low immunogenicity and high efficacy.

Shiga toxin-producing infections are difficult to treat due to the risk of antibiotic-induced stress upregulating the production of toxins, medical treatment is consequently limited to supportive care to prevent the development of hemolytic uremic syndrome (HUS). Here, we introduce a potentially therapeutic humanized mouse monoclonal antibody (Hu-mAb 2-5) targeting Stx2a, the most common Shiga toxin subtype identified from outbreaks. We demonstrate that Hu-mAb 2-5 has low immunogenicity in healthy adults and high neutralizing efficacy , protecting mice from mortality and HUS-related tissue damage.

A Sensitive, Cell-Based Assay for Measuring Low-Level Biological Activity of α-Amanitin.

α-Amanitin is one of the primary toxins produced by the poisonous mushroom genus, . Because it is odorless and tasteless, it is an important cause of death from the consumption of misidentified mushrooms. To study the thermal stability of α-amanitin, novel cell-based assays were developed to measure the toxin's activity, based on the inhibition of RNA polymerase II by α-amanitin.

Development of Thermally Stable Nanobodies for Detection and Neutralization of Staphylococcal Enterotoxin B.

In this study, sixteen unique staphylococcal enterotoxin B (SEB)-reactive nanobodies (nbs), including ten monovalent and six bivalent nbs, were developed. All characterized nbs were highly specific for SEB and did not cross-react with other staphylococcal enterotoxins (SE). Several formats of highly sensitive enzyme-linked immunosorbent assays (ELISAs) were established using SEB nbs and a polyclonal antibody (pAb).

T-cell receptor Vβ8 for detection of biologically active streptococcal pyrogenic exotoxin type C.

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.

The Effect of Tannin-Rich Witch Hazel on Growth of Probiotic .

Probiotic bacteria help maintain microbiome homeostasis and promote gut health. Maintaining the competitive advantage of the probiotics over pathogenic bacteria is a challenge, as they are part of the gut microbiome that is continuously exposed to digestive and nutritional changes and various stressors. Witch hazel that is rich in hamamelitannin (WH, whISOBAX) is an inhibitor of growth and virulence of pathogenic bacteria.

Ex Vivo and In Vitro Methods for Detection of Bioactive Staphylococcal Enterotoxins.

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.

Human Leukemia T-Cell Lines as Alternatives to Animal Use for Detecting Biologically Active Staphylococcal Enterotoxin Type B.

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.

Quantitative bioluminescence assay for measuring Bacillus cereus nonhemolytic enterotoxin complex.

Bacillus cereus is a foodborne pathogen causing emesis and diarrhea in those affected. It is assumed that the non-hemolytic enterotoxin (Nhe) plays a key role in B. cereus induced diarrhea.

CCD Based Detector for Detection of Abrin Toxin Activity.

Abrin is a highly potent and naturally occurring toxin produced in the seeds of (Rosary Pea) and is of concern as a potential bioterrorism weapon. There are many rapid and specific assay methods to detect this toxic plant protein, but few are based on detection of toxin activity, critical to discern biologically active toxin that disables ribosomes and thereby inhibits protein synthesis, producing cytotoxic effects in multiple organ systems, from degraded or inactivated toxin which is not a threat. A simple and low-cost CCD detector system was evaluated with colorimetric and fluorometric cell-based assays for abrin activity; in the first instance measuring the abrin suppression of mitochondrial dehydrogenase in Vero cells by the MTT-formazan method and in the second instance measuring the abrin suppression of green fluorescent protein (GFP) expression in transduced Vero and HeLa cells.

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 . Staphylococcal enterotoxin type A (SEA) is the predominant toxin produced by 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.

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

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.

Interleukin 2 Secretion by T Cells for Detection of Biologically Active Staphylococcal Enterotoxin Type E.

Staphylococcus aureus is a significant worldwide source of clinical infections and foodborne illnesses; it acts through the synthesis of a group of enterotoxins (SEs) that cause gastroenteritis and also function as superantigens that activate T cells, resulting in massive cytokine production, yielding life-threatening toxicity. It is important that methods for detection and quantification of these toxins respond to their activity and not just the presence of the toxin molecule, which may be deactivated. Traditionally, live animals have been used to test for emesis following administration of the toxin-containing sample.

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

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.

Sensitive, Rapid, Quantitative and in Vitro Method for the Detection of Biologically Active Staphylococcal Enterotoxin Type E.

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.

Low cost quantitative digital imaging as an alternative to qualitative in vivo bioassays for analysis of active aflatoxin B1.

Aflatoxin B1 (AFB1) producing fungi contaminate food and feed and are a major health concern. To minimize the sources and incidence of AFB1 illness there is a need to develop affordable, sensitive mobile devices for detection of active AFB1. In the present study we used a low cost fluorescence detector and describe two quantitative assays for detection of detoxified and active AFB1 demonstrating that AFB1 concentration can be measured as intensity of fluorescence.

New Stx2e Monoclonal Antibodies for Immunological Detection and Distinction of Stx2 Subtypes.

Background: Stx2e is a primary virulence factor in STEC strains that cause edema disease in neonatal piglets. Though Stx2a and Stx2e are similar, many antibody-based Stx detection kits are designed to detect Stx2a and do not recognize the Stx2e subtype.

Methods And Findings: Four monoclonal antibodies against Stx2e were developed and characterized.

Plant compounds enhance the assay sensitivity for detection of active Bacillus cereus toxin.

Bacillus cereus is an important food pathogen, producing emetic and diarrheal syndromes, the latter mediated by enterotoxins. The ability to sensitively trace and identify this active toxin is important for food safety. This study evaluated a nonradioactive, sensitive, in vitro cell-based assay, based on B.

Intracellular trehalose and sorbitol synergistically promoting cell viability of a biocontrol yeast, Pichia anomala, for aflatoxin reduction.

Pichia anomala (Wickerhamomyces anomalus) WRL-076 was discovered by a visual screening bioassay for its antagonism against Aspergillus flavus. The yeast was shown to significantly inhibit aflatoxin production and the growth of A. flavus.

Sensitive detection of active Shiga toxin using low cost CCD based optical detector.

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.

Quantitative analysis of staphylococcus enterotoxin A by differential expression of IFN-γ in splenocyte and CD4⁺ T-cells.

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.

Rapid detection of predation of Escherichia coli O157:H7 and sorting of bacterivorous Tetrahymena by flow cytometry.

Protozoa are known to harbor bacterial pathogens, alter their survival in the environment and make them hypervirulent. Rapid non-culture based detection methods are required to determine the environmental survival and transport of enteric pathogens from point sources such as dairies and feedlots to food crops grown in proximity. Grazing studies were performed on a soil isolate of Tetrahymena fed green fluorescent protein (GFP) expressing Escherichia coli O157:H7 to determine the suitability of the use of such fluorescent prey bacteria to locate and sort bacterivorous protozoa by flow cytometry.

Microwave Heating Inactivates Shiga Toxin (Stx2) in Reconstituted Fat-Free Milk and Adversely Affects the Nutritional Value of Cell Culture Medium.

Microwave exposure is a convenient and widely used method for defrosting, heating, and cooking numerous foods. Microwave cooking is also reported to kill pathogenic microorganisms that often contaminate food. In this study, we tested whether microwaves would inactivate the toxicity of Shiga toxin 2 (Stx2) added to 5% reconstituted fat-free milk administered to monkey kidney Vero cells.

Non-linear relationships between aflatoxin B₁ levels and the biological response of monkey kidney vero cells.

Aflatoxin-producing fungi contaminate food and feed during pre-harvest, storage and processing periods. Once consumed, aflatoxins (AFs) accumulate in tissues, causing illnesses in animals and humans. Most human exposure to AF seems to be a result of consumption of contaminated plant and animal products.