Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

By fusion of mouse spleen cells immunized with five different staphylococcal enterotoxins (SEA, SEB, SEC2, SED, and SEE) with myeloma cells, we obtained 15 hybridomas producing monoclonal antibodies (mAbs). Four mAbs were reactive with both SEA and SEE, whereas 8 mAbs were reactive with SEB and SEC2. One mAb reacted with SEA, SED, and SEE. The other two mAbs were found to be reactive with all five serotypes of SEs. The mAbs specific for five serotypes of SEs were found to be most reactive with SED, reactive with SEA, and slightly less reactive with SEB, SEC2, and SEE. Those mAbs with specificities for all serotypes of SEs may be valuable to prepare immunoadsorbent(s) for isolation of SEs and to detect SEs in foods and clinical specimens involved in outbreaks of staphylococcal food poisoning.
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PMID:Murine monoclonal antibodies reactive with staphylococcal enterotoxins A, B, C2, D, and E. 185 48

A study was made of the presence of antibodies (Ab) to staphylococcal enterotoxins A to E (SEA-SEE) in the serum and milk of 133 healthy goats, using a competitive ELISA method. Antibodies to some enterotoxins were detected in 83 sera (62.4%) and in 41 (30.8%) milk samples. In serum, antibodies to all SE types were detected, the most frequent being antibodies to SEA (24.8%). Milk contained antibodies to SEA, SEB and SEC, the latter being the most frequent (24.8%). A statistical study was performed to correlate the number of animals harbouring antibodies to a given enterotoxin with the presence in these animals of staphylococci producing that enterotoxin.
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PMID:Detection of antibodies to staphylococcal enterotoxins in the serum and milk of healthy goats. 205 81

For 77 strains of Staphylococcus aureus freshly isolated from different foods, growth, enterotoxin and TNase production were determined in intervals of 1.5 degrees C +/- 0.5 degrees C by cultivating them in a temperature-gradient incubator between 5 and 50 degrees C for up to 7 days. All the strains were coagulase, DNase and lysostaphin positive but only 58% formed one or two enterotoxins type SEA, SEB or SEE. All strains grew within 7 days in brain heart infusion and had lower and upper temperature limits for growth and TNase production of between 6.5 and 12.5 degrees C, and 39.5 and 48.5 degrees C respectively. The lower and upper temperature limits for production of enterotoxins were between 14 and 38 degrees C, and between 35 and 44 degrees C respectively. Enterotoxin forming isolates either showed narrow (3 to 4 degrees C) or wide (10 to 20 degrees C) ranges of enterotoxin production, irrespective of their temperature range of growth and TNase production. None of the 12 specific physiological attributes used for differentiation could be correlated to toxin type or the temperature requirement of the toxin production. No correlation between the origin and the physiological characters could be detected.
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PMID:Temperature limits of growth, TNase and enterotoxin production of Staphylococcus aureus strains isolated from foods. 222 19

The stimulation of T cells by staphylococcal enterotoxins (SE) is strictly dependent on major histocompatibility complex (MHC) class II-bearing cells. The interaction between SE and MHC class II molecules was studied on the human B cell lymphoma Raji and its MHC class II-negative variant RJ 2.2.5. Affinity purification with SEA and SEB matrix allowed the isolation of HLA-DR-like molecules from detergent lysates of 125I surface-labeled Raji cells, but not from RJ 2.2.5 cells. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis also revealed preferences in the binding of other SE such as SED, SEE and toxic shock syndrome toxin 1 to DR-like molecules, SEC2 to HLA-DQ-like molecules and SEC3 to DR- and DQ-like molecules. Preadsorption of the different MHC class II MHC isotypes confirmed the preferential binding of SEA to DR and of SEC2 to DQ. The implications of these findings for the understanding of SE-induced T cell activation and the potency of SE as a tool in the study of MHC class II antigens are discussed.
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PMID:Different staphylococcal enterotoxins bind preferentially to distinct major histocompatibility complex class II isotypes. 259 4

340 S. aureus strains, isolated either from routine food test samples, or from food leftovers, from healthy or sick persons in cases of suspected food poisoning in various places of the Federal Republic of Germany, were tested for enterotoxin production. The enterotoxin types A, B and C (SEA, SEB and SEC) were determined both by the ELISA and the microslide test (MS-test), the enterotoxin types D and E by the MS-test only. Comparison of the two test methods clearly shows that the ELISA technique is superior to the MS method: The sensitivity of the ELISA was at 2.5 ng, whereas that of the MS-test was limited to approximately 1 microgram. The ELISA revealed 6.2% more of the strains as enterotoxin producers, and reproducibility of the test results was also better with the ELISA than with the MS-test. Furthermore, the ELISA is far more efficient, consuming less test reagents, and with a capacity for testing more strains in a shorter time procedure. The incidence rate of the various enterotoxin types, referred to one representative strain each per outbreak of food poisoning or group of persons investigated, is as follows: 45.3% SEA, 17.2% SEB, 23.4% SEC. The incidence rate of SED, SEE or SE-type combinations was less than 5%. In sick persons, SEA- and SEC-producing strains occurred within the same range, i.e. 34.8% and 30.4% respectively. SEA-producing S. aureus strains had the highest frequency in food samples (61.5%) and in healthy individuals (53.6%).
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PMID:[Demonstration of enterotoxin in Staphylococcus aureus cultures by the ELISA test and the microslide test]. 640 34

Superantigens have been suggested to act as powerful TCR V beta-specific inducers of T cell reactivity in autoimmune diseases. We have investigated the capacity of staphylococcal enterotoxins (SE) to prime autoreactive T cell responses in naive animals in the Lewis rat model of experimental autoimmune encephalomyelitis (EAE), where myelin basic protein (MBP)-specific CD4+ effector T cells express almost exclusively V beta 8.2 TCR elements. By taking advantage of the reactivity of V beta 8.2+ MBP-specific T cells to SEE but not to other SEs in vitro, we estimated the potential of different SEs (SEA, SEB, and SEE) to induce a primary T cell response to soluble MBP in vivo. Upon immunization of naive rats with soluble MBP alone or MBP and SEB (which is only a very weak superantigen for rat T cells), no MBP-responses could be retrieved. Similarly, when coimmunizing naive rats with MBP and V beta 8.2-activating SEE, no autoreactivity was inducible. By contrast, coimmunization of animals with soluble MBP and the superantigen SEA that is strongly activating various T cell subpopulations in Lewis rats but not V beta 8.2+ (i.e., potentially MBP reactive) T cells led to a significant primary MBP-specific T cell autoreactivity. These SEA-induced MBP-reactive T cells expressed V beta 8.2 TCRs at levels similar to those seen in autoreactive T cells conventionally induced by immunization with MBP administered in complete Freund's adjuvant (CFA) and could induce disease in a transfer model of EAE. Thus, our results are consistent with the notion that superantigens are able to induce primary T cell responses to soluble autoantigens by a non-V beta specific mechanism of bystander priming.
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PMID:Superantigens induce primary T cell responses to soluble autoantigens by a non-V beta-specific mechanism of bystander activation. 753 95

The three-dimensional structure of staphylococcal enterotoxin C2 has been determined at 2.7 A resolution by x-ray diffraction, while the structures of enterotoxins A and E have been modelled based on their sequence homology to other staphylococcal enterotoxins. The T-cell receptor-binding sites of staphylococcal enterotoxin (SE) B and SEC2 are compared and the stereochemical interactions likely to be responsible for their differing V beta specificities are identified. A similar comparison is made between SEA and SEE.
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PMID:Residues defining V beta specificity in staphylococcal enterotoxins. 755 30

A defining characteristic of superantigens is their ability to stimulate T cells based predominantly on the type of variable segment of the T cell receptor (TCR) beta chain (V beta). The V beta specificity of these toxins most likely results from direct contact between the toxin and the TCR, although the low affinity nature of this binding has prevented direct assessment of this interaction. To identify important functional sites on the toxin, we created chimeric enterotoxin genes between staphylococcal enterotoxins A and E (SEA and SEE) and tested the V beta specificity of the chimeric toxins. This approach allowed us to identify three amino acid residues in the extreme COOH terminus of these toxins that are largely responsible for their ability to stimulate either human V beta 5- or V beta 8-bearing T cells, or mouse V beta 3 or V beta 11. We also found that residues in the NH2 terminus were required for wild-type levels of V beta-specific T cell activation, suggesting that the NH2 and COOH ends of these superantigens may come together to form the full TCR V beta contact site. SEA and SEE also differ with respect to their class II binding characteristics. Using the same chimeric molecules, we demonstrate that the first third of the molecule controls the class II binding phenotype. These data lead us to propose that for SEA and SEE, and perhaps for all bacterial-derived superantigens, the COOH and NH2 termini together form the contact sites for the TCR and therefore largely determine the V beta specificity of the toxin, while the NH2 terminus alone binds major histocompatibility complex class II molecules. The predominant role of the COOH terminus of bacterial superantigens in determining V beta specificity resembles current models being proposed for virally encoded superantigens, suggesting that these molecules may demonstrate some structural relationship not seen at the amino acid level.
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PMID:Localization of a site on bacterial superantigens that determines T cell receptor beta chain specificity. 767 49

Zinc is known to be greatly involved in the regulation of immune functions. Pharmacological zinc supplementation, leading to serum zinc concentrations of more than 0.025 mM, has often been suggested to improve immune responses. However, the exact influence of elevated zinc level on immune functions has not yet been investigated. We found that zinc level selectively enhances cytokine induction by lipopolysaccharide (LPS) in a concentration-dependent fashion: as little as 0.0125 mM supplemental zinc led to nearly 50% elevated interleukin-1 beta (IL-1 beta) levels both in polymorphonuclear cells (PBMC) and whole-blood cultures. The secretion of interferon-gamma (IFN-gamma) could be increased more than 10-fold by 0.1 mM zinc. This could not be observed during stimulation with phytohaemagglutin (PHA). In contrast, zinc levels concentration-dependently down-regulated monocyte activation caused by the superantigens, staphylococcal enterotoxins A and E (SEA, SEE, more than 90% down-regulation by 0.1 mM zinc), the Mycoplasma arthritidis-derived superantigen (MAS), but not toxic shock syndrome toxin-1 (TSST-1), while T-cell response remained unaffected. This was not the result of chemical degradation of the superantigens. We assume that zinc concentration regulates interactions between SEA, SEE and MAS, but not TSST-1 and their major histocompatibility complex (MHC) class II-binding sites. Our data demonstrate that zinc levels control the secretion of IFN-gamma and monokines after both LPS and superantigen challenge within a clinically relevant range of concentrations. This reveals new perspectives and indications for zinc supplementation and also indicates potential risks of therapeutic application of zinc.
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PMID:Zinc regulates cytokine induction by superantigens and lipopolysaccharide. 775 Oct 4

Staphylococcus aureus strain D4508 is a toxic shock syndrome toxin 1-negative clinical isolate from a nonmenstrual case of toxic shock syndrome (TSS). In the present study, we have purified and characterized a new exotoxin from the extracellular products of this strain. This toxin was found to have a molecular mass of 25.14 kD by mass spectrometry and an isoelectric point of 5.65 by isoelectric focusing. We have also cloned and sequenced its corresponding genomic determinant. The DNA sequence encoding the mature protein was found to be 654 base pairs and is predicted to encode a polypeptide of 218 amino acids. The deduced protein contains an NH2-terminal sequence identical to that of the native protein. The calculated molecular weight (25.21 kD) of the recombinant mature protein is also consistent with that of the native molecules. When injected intravenously into rabbits, both the native and recombinant toxins induce an acute TSS-like illness characterized by high fever, hypotension, diarrhea, shock, and in some cases death, with classical histological findings of TSS. Furthermore, the activity of the toxin is specifically enhanced by low quantities of endotoxins. The toxicity can be blocked by rabbit immunoglobulin G antibody specific for the toxin. Western blotting and DNA sequencing data confirm that the protein is a unique staphylococcal exotoxin, yet shares significant sequence homology with known staphylococcal enterotoxins, especially the SEA, SED, and SEE toxins. We conclude therefore that this 25-kD protein belongs to the staphylococcal enterotoxin gene family that is capable of inducing a TSS-like illness in rabbits.
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PMID:Characterization and biological properties of a new staphylococcal exotoxin. 796 53


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