Artykuły w czasopismach: „Alpha toxin”

1

Liang, Xudong, Meiying Yan i Yinduo Ji. "The H35A Mutated Alpha-Toxin Interferes with Cytotoxicity of Staphylococcal Alpha-Toxin". Infection and Immunity 77, nr 3 (22.12.2008): 977–83. http://dx.doi.org/10.1128/iai.00920-08.

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ABSTRACT Staphylococcal alpha-toxin is an important virulence factor for Staphylococcus aureus to cause severe infections. In this study, we explored whether the toxoid of alpha-toxin may be utilized to block the toxicity of wild-type alpha-toxin. We created a series of H35A mutated alpha-toxin expression strains and revealed that the H35A mutation eliminates the activity of alpha-toxin using a human lung epithelial cell line (A549). More importantly, we found that either the pretreatment or simultaneous treatment of the epithelial cells with alpha-toxin-H35A completely disrupted the cytotoxicity of alpha-toxin. Specifically, we demonstrated that alpha-toxin-H35A can effectively interfere with the pore formation and the internalization of alpha-toxin using cytotoxicity and immunofluorescence assays. In addition, we found that the removal of either the 30-amino-acid (aa) or 99-aa C-terminal region of alpha-toxin-H35A reactivated its cytotoxicity, indicating that interactions between the alanine residue at position 35 and these C-terminal regions may be associated with interrupting the toxic activity of alpha-toxin-H35A. Taken together, these results suggest that the alpha-toxin-H35A protein may be developed as a potential alternative therapeutic agent for treating early stages of S. aureus infections.

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2

Bernheimer, Alan W. "STAPHYLOCOCCAL ALPHA TOXIN*". Annals of the New York Academy of Sciences 128, nr 1 (16.12.2006): 112–23. http://dx.doi.org/10.1111/j.1749-6632.1965.tb11633.x.

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3

Palmer. "Staphyloccal alpha toxin". Journal of Applied Microbiology 84, S1 (lipiec 1998): 125S—126S. http://dx.doi.org/10.1046/j.1365-2672.1998.0840s1125s.x.

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Jepson, Marie, Angela Howells, Helen L. Bullifent, Barbara Bolgiano, Dennis Crane, Julie Miller, Jane Holley, Pramukh Jayasekera i Richard W. Titball. "Differences in the Carboxy-Terminal (Putative Phospholipid Binding) Domains of Clostridium perfringens andClostridium bifermentans Phospholipases C Influence the Hemolytic and Lethal Properties of These Enzymes". Infection and Immunity 67, nr 7 (1.07.1999): 3297–301. http://dx.doi.org/10.1128/iai.67.7.3297-3301.1999.

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ABSTRACT The phospholipases C of C. perfringens (alpha-toxin) and C. bifermentans (Cbp) show >50% amino acid homology but differ in their hemolytic and toxic properties. We report here the purification and characterisation of alpha-toxin and Cbp. The phospholipase C activity of alpha-toxin and Cbp was similar when tested with phosphatidylcholine in egg yolk or in liposomes. However, the hemolytic activity of alpha-toxin was more than 100-fold that of Cbp. To investigate whether differences in the carboxy-terminal domains of these proteins were responsible for differences in the hemolytic and toxic properties, a hybrid protein (NbiCα) was constructed comprising the N domain of Cbp and the C domain of alpha-toxin. The hemolytic activity of NbiCαwas 10-fold that of Cbp, and the hybrid enzyme was toxic. These results confirm that the C-terminal domain of these proteins confers different properties on the enzymatically active N-terminal domain of these proteins.

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5

Zhu, H., i H. Bussey. "Mutational analysis of the functional domains of yeast K1 killer toxin." Molecular and Cellular Biology 11, nr 1 (styczeń 1991): 175–81. http://dx.doi.org/10.1128/mcb.11.1.175.

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To determine the functional domains of K1 killer toxin, we analyzed the phenotypes of a set of mutations throughout regions encoding the alpha- and beta-toxin subunits that allow secretion of mutant toxins. A range of techniques have been used to examine the ability of mutant toxins to bind to beta-glucan cell wall receptor and to form lethal ion channels. Our results indicate that both the alpha and beta subunits are involved in beta-glucan receptor binding. Defects in ion channel formation and toxin immunity are confined to the hydrophobic alpha subunit of the toxin.

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6

Zhu, H., i H. Bussey. "Mutational analysis of the functional domains of yeast K1 killer toxin". Molecular and Cellular Biology 11, nr 1 (styczeń 1991): 175–81. http://dx.doi.org/10.1128/mcb.11.1.175-181.1991.

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To determine the functional domains of K1 killer toxin, we analyzed the phenotypes of a set of mutations throughout regions encoding the alpha- and beta-toxin subunits that allow secretion of mutant toxins. A range of techniques have been used to examine the ability of mutant toxins to bind to beta-glucan cell wall receptor and to form lethal ion channels. Our results indicate that both the alpha and beta subunits are involved in beta-glucan receptor binding. Defects in ion channel formation and toxin immunity are confined to the hydrophobic alpha subunit of the toxin.

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7

Yarovinsky, Timur O., Martha M. Monick, Matthias Husmann i Gary W. Hunninghake. "Interferons Increase Cell Resistance to Staphylococcal Alpha-Toxin". Infection and Immunity 76, nr 2 (10.12.2007): 571–77. http://dx.doi.org/10.1128/iai.01088-07.

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ABSTRACT Many bacterial pathogens, including Staphylococcus aureus, use a variety of pore-forming toxins as important virulence factors. Staphylococcal alpha-toxin, a prototype β-barrel pore-forming toxin, triggers the release of proinflammatory mediators and induces primarily necrotic death in susceptible cells. However, whether host factors released in response to staphylococcal infections may increase cell resistance to alpha-toxin is not known. Here we show that prior exposure to interferons (IFNs) prevents alpha-toxin-induced membrane permeabilization, the depletion of ATP, and cell death. Moreover, pretreatment with IFN-α decreases alpha-toxin-induced secretion of interleukin 1β (IL-1β). IFN-α, IFN-β, and IFN-γ specifically protect cells from alpha-toxin, whereas tumor necrosis factor alpha (TNF-α), IL-6, and IL-4 have no effects. Furthermore, we show that IFN-α-induced protection from alpha-toxin is not dependent on caspase-1 or mitogen-activated protein kinases, but requires protein synthesis and fatty acid synthase activity. Our results demonstrate that IFNs may increase cell resistance to staphylococcal alpha-toxin via the regulation of lipid metabolism and suggest that interferons play a protective role during staphylococcal infections.

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8

TSIOURIS (Β.Σ. ΤΣΙΟΥΡΗΣ), V. S., I. GEORGOPOULOU (ΓΕΩΡΓΟΠΟΥΛΟΥ) i E. PETRIDOU (Ε. ΠΕΤΡΙΔΟΥ). "Update on the toxins of Clostridium perfringens and their actions". Journal of the Hellenic Veterinary Medical Society 61, nr 3 (17.11.2017): 241. http://dx.doi.org/10.12681/jhvms.14892.

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Clostridia appeared as a distinct class, approximately 2.7 billion years ago, before the initial formation of oxygen. Clostridium perfringens is widely distributed throughout the environment due to its ability to form spores. Furthermore, it is a member of intestinal microbiota in animals and human. In 2002, the complete genome of C perfringens strain 13 was published. Genomic analysis has revealed that C. perfringens lacks the genetic machinery to produce 13 essential amino acids and it obtains these in vivo via the action of its toxins. Toxins of C perfringens can be divided into major, minor and enterotoxin. C perfringens strains are classified into five toxinotypes (A, B, C, D and E), based on the production of four major toxins. Alpha toxin is the best and most studied major toxin of C perfringens and it was the first bacterial toxin established to possess enzymatic activity. It has haemolytic, necrotic and cytolytic activity, it can lyse platelets and leukocytes and it can damage fibroblasts and muscle cell membranes. Expression of epa gene, which is responsible for the production of alpha toxin by C perfringens, is down-regulated in the normal healthy gut, but it is upregulated to initiate enteric disease in response to an environmental signal. C perfringens appears to be regulated in a quorum sensing manner, using oligopeptides, AI-2 or both, to regulate expression of the epa gene, and thus the synthesis of alpha toxin. Beta toxin is recognized as an important agent in necrotic enteritis of humans and it is the second most lethal C. perfringens toxin following epsilon toxin. Beta toxin is a membrane spanning protein that oligomerizes to form channels in susceptible cells or it primarily acts as a neurotoxin. Epsilon toxin is the most potent of the C. perfringens toxins and the third most potent neurotoxin from the Clostridium spp., following botulinum and tetanus toxins. Epsilon toxin of C perfringens type D causes enterotoxaemia and pulpy kidneys disease of lambs. Iota toxin causes disruption of the actin cytoskeleton and cell barrier integrity and it is the less toxic of the major toxins of C perfringens. Although C perfringens enterotoxin is not classified as one of the major toxins of C perfringens, it is the third most common cause of food poisoning in industrialized nations. It is not secreted by the cells of growing bacteria, but it is released only with the sporulation of C perfringens. Not all strains of C perfringens carry the epe gene, which is responsible for the production of enterotoxin. Theta toxin is a pore-forming cytolysin that can lyse red blood cells. It is produced by all types of C perfringens. Together with alpha-toxin, theta-toxin modulates the host inflammatory response. ß2 toxin is a pore forming toxin which is involved in necrotic enteritis of swine and horse, in haemorragic enteritis of bovine in diarrhea cases of dogs and along with enterotoxin in diarrhea cases of humans. Recently, -NetB, a novel toxin that is associated with broiler necrotic enteritis, has been described. The mechanism of its action seems to involve the formation of small hydrophilic pores. Other toxins of C. perfringens include λ-toxin, ô-toxin, μ-toxin, v-toxin, κ-toxin, a-clostripain like protease and neuraminidase/sialidase. These toxins can act as enzymes, while many of them can act synergically or supplementally with major pore forming toxins. Potentially, C. perfringens might produce more toxins, which have not been identified. Finally, the actions of C. perfringens toxins, major or minor, in some diseases have not been figured out.

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9

Nilsson, Ing-Marie, Orla Hartford, Timothy Foster i Andrzej Tarkowski. "Alpha-Toxin and Gamma-Toxin Jointly PromoteStaphylococcus aureus Virulence in Murine Septic Arthritis". Infection and Immunity 67, nr 3 (1.03.1999): 1045–49. http://dx.doi.org/10.1128/iai.67.3.1045-1049.1999.

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ABSTRACT Septic arthritis is a common and feared complication of staphylococcal infections. Staphylococcus aureus produces a number of potential virulence factors including certain adhesins and enterotoxins. In this study we have assessed the roles of cytolytic toxins in the development of septic arthritis by inoculating mice withS. aureus wild-type strain 8325-4 or isogenic mutants differing in the expression of alpha-, beta-, and gamma-toxin production patterns. Mice inoculated with either an alpha- or beta-toxin mutant showed degrees of inflammation, joint damage, and weight decrease similar to wild-type-inoculated mice. In contrast, mice inoculated with either double (alpha- and gamma-toxin-deficient)- or triple (alpha-, beta-, and gamma-toxin-deficient)-mutant S. aureus strains showed lower frequency and severity of arthritis, measured both clinically and histologically, than mice inoculated with the wild-type strain. We conclude that simultaneous production of alpha- and gamma-toxin is a virulence factor in S. aureusarthritis.

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10

Awad, Milena M., Darren M. Ellemor, Richard L. Boyd, John J. Emmins i Julian I. Rood. "Synergistic Effects of Alpha-Toxin and Perfringolysin O in Clostridium perfringens-Mediated Gas Gangrene". Infection and Immunity 69, nr 12 (1.12.2001): 7904–10. http://dx.doi.org/10.1128/iai.69.12.7904-7910.2001.

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ABSTRACT To examine the synergistic effects of alpha-toxin and perfringolysin O in clostridial myonecrosis, homologous recombination was used to construct an alpha-toxin deficient derivative of a perfringolysin O mutant of Clostridium perfringens. The subsequent strain was complemented with separate plasmids that carried the alpha-toxin structural gene (plc), the perfringolysin O gene (pfoA), or both toxin genes, and the resultant isogenic strains were examined in a mouse myonecrosis model. Synergistic effects were clearly observed in these experiments. Infection with the control strain, which did not produce either toxin, resulted in very minimal gross pathological changes, whereas the isogenic strain that was reconstituted for both toxins produced a pathology that was clearly more severe than when alpha-toxin alone was reconstituted. These changes were most apparent in the rapid spread of the disease, the gross pathology of the footpad and in the rate at which the mice had to be euthanatized for ethical reasons. Elimination of both alpha-toxin and perfringolysin O production removed most of the histopathological features typical of clostridial myonecrosis. These effects were restored when the mutant was complemented with the alpha-toxin structural gene, but reconstituting only perfringolysin O activity produced vastly different results, with regions of coagulative necrosis, apparently enhanced by vascular disruption, being observed. Reconstitution of both alpha-toxin and perfringolysin O activity produced histopathology most similar to that observed with the alpha-toxin reconstituted strain. The spreading of myonecrosis was very rapid in these tissues, and coagulative necrosis appeared to be restricted to the lumen of the blood vessels. The results of these virulence experiments clearly support the hypothesis that alpha-toxin and perfringolysin O have a synergistic effect in the pathology of gas gangrene.

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11

Bhakdi, S., i J. Tranum-Jensen. "Alpha-toxin of Staphylococcus aureus." Microbiological Reviews 55, nr 4 (1991): 733–51. http://dx.doi.org/10.1128/mmbr.55.4.733-751.1991.

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12

Bhakdi, S., i J. Tranum-Jensen. "Alpha-toxin of Staphylococcus aureus." Microbiological Reviews 55, nr 4 (1991): 733–51. http://dx.doi.org/10.1128/mr.55.4.733-751.1991.

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13

Thelestam, Monica, i Lennart Blomqvist. "Staphylococcal alpha toxin — recent advances". Toxicon 26, nr 1 (styczeń 1988): 51–65. http://dx.doi.org/10.1016/0041-0101(88)90137-7.

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14

Fisher, Derek J., Mariano E. Fernandez-Miyakawa, Sameera Sayeed, Rachael Poon, Victoria Adams, Julian I. Rood, Francisco A. Uzal i Bruce A. McClane. "Dissecting the Contributions of Clostridium perfringens Type C Toxins to Lethality in the Mouse Intravenous Injection Model". Infection and Immunity 74, nr 9 (wrzesień 2006): 5200–5210. http://dx.doi.org/10.1128/iai.00534-06.

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ABSTRACT The gram-positive anaerobe Clostridium perfringens produces a large arsenal of toxins that are responsible for histotoxic and enteric infections, including enterotoxemias, in humans and domestic animals. C. perfringens type C isolates, which cause rapidly fatal diseases in domestic animals and enteritis necroticans in humans, contain the genes for alpha toxin (plc), perfringolysin O (pfoA), beta toxin (cpb), and sometimes beta2 toxin (cpb2) and/or enterotoxin (cpe). Due to the economic impact of type C-induced diseases, domestic animals are commonly vaccinated with crude type C toxoid (prepared from inactivated culture supernatants) or bacterin/toxoid vaccines, and it is not clear which toxin(s) present in these vaccines actually elicits the protective immune response. To improve type C vaccines, it would be helpful to assess the contribution of each toxin present in type C supernatants to lethality. To address this issue, we surveyed a large collection of type C isolates to determine their toxin-producing abilities. When late-log-phase vegetative culture supernatants were analyzed by quantitative Western blotting or activity assays, most type C isolates produced at least three lethal toxins, alpha toxin, beta toxin, and perfringolysin O, and several isolates also produced beta2 toxin. In the mouse intravenous injection model, beta toxin was identified as the main lethal factor present in type C late-log-phase culture supernatants. This conclusion was based on monoclonal antibody neutralization studies and regression analyses in which the levels of alpha toxin, beta toxin, perfringolysin O, and beta2 toxin production were compared with lethality. Collectively, our results highlight the importance of beta toxin for type C-induced toxemia.

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15

Tegmark, Karin, Eva Morfeldt i Staffan Arvidson. "Regulation of agr-Dependent Virulence Genes in Staphylococcus aureus by RNAIII from Coagulase-Negative Staphylococci". Journal of Bacteriology 180, nr 12 (15.06.1998): 3181–86. http://dx.doi.org/10.1128/jb.180.12.3181-3186.1998.

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ABSTRACT Many of the genes coding for extracellular toxins, enzymes, and cell surface proteins in Staphylococcus aureus are regulated by a 510-nucleotide (nt) RNA molecule, RNAIII. Transcription of genes encoding secreted toxins and enzymes, includinghla (alpha-toxin), saeB (enterotoxin B),tst (toxic shock syndrome toxin 1), and ssp(serine protease), is stimulated, while transcription of genes encoding cell surface proteins, like spa (protein A) andfnb (fibronectin binding proteins), is repressed. Besides being a regulator, RNAIII is also an mRNA coding for staphylococcal delta-lysin. We have identified RNAIII homologs in three different coagulase-negative staphylococci (CoNS), i.e., Staphylococcus epidermidis, Staphylococcus simulans, andStaphylococcus warneri. RNAIII from these CoNS turned out to be very similar to that of S. aureus and contained open reading frames encoding delta-lysin homologs. Though a number of big insertions and/or deletions have occurred, mainly in the 5′ half of the molecules, the sequences show a high degree of identity, especially in the first 50 and last 150 nt. The CoNS RNAIII had the ability to completely repress transcription of protein A in an RNAIII-deficientS. aureus mutant and the ability to stimulate transcription of the alpha-toxin and serine protease genes. However, the stimulatory effect was impaired compared to that of S. aureus RNAIII, suggesting that these regulatory functions are independent. By creating S. epidermidis-S. aureus RNAIII hybrids, we could also show that both the 5′ and 3′ halves of the RNAIII molecule are involved in the transcriptional regulation of alpha-toxin and serine protease mRNAs in S. aureus.

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16

Sharma-Kuinkel, Batu K., Yuling Wu, David E. Tabor, Hoyin Mok, Bret R. Sellman, Amy Jenkins, Li Yu i in. "Characterization of Alpha-ToxinhlaGene Variants, Alpha-Toxin Expression Levels, and Levels of Antibody to Alpha-Toxin in Hemodialysis and Postsurgical Patients with Staphylococcus aureus Bacteremia". Journal of Clinical Microbiology 53, nr 1 (12.11.2014): 227–36. http://dx.doi.org/10.1128/jcm.02023-14.

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Alpha-toxin is a majorStaphylococcus aureusvirulence factor. This study evaluated potential relationships betweenin vitroalpha-toxin expression ofS. aureusbloodstream isolates, anti-alpha-toxin antibody in serum of patients withS. aureusbacteremia (SAB), and clinical outcomes in 100 hemodialysis and 100 postsurgical SAB patients. Isolates underwentspatyping andhlasequencing. Serum anti-alpha-toxin IgG and neutralizing antibody levels were measured by using an enzyme-linked immunosorbent assay and a red blood cell (RBC)-based hemolysis neutralization assay. Neutralization of alpha-toxin by an anti-alpha-toxin monoclonal antibody (MAb MEDI4893) was tested in an RBC-based lysis assay. Most isolates encodedhla(197/200; 98.5%) and expressed alpha-toxin (173/200; 86.5%).In vitroalpha-toxin levels were inversely associated with survival (cure, 2.19 μg/ml, versus failure, 1.09 μg/ml;P< 0.01). Both neutralizing (hemodialysis, 1.26 IU/ml, versus postsurgical, 0.95;P< 0.05) and IgG (hemodialysis, 1.94 IU/ml, versus postsurgical, 1.27;P< 0.05) antibody levels were higher in the hemodialysis population. Antibody levels were also significantly higher in patients infected with alpha-toxin-expressingS. aureusisolates (P< 0.05). Levels of both neutralizing antibodies and IgG were similar among patients who were cured and those not cured (failures). Sequence analysis ofhlarevealed 12 distincthlagenotypes, and all genotypic variants were susceptible to a neutralizing monoclonal antibody in clinical development (MEDI4893). These data demonstrate that alpha-toxin is highly conserved in clinicalS. aureusisolates. Higherin vitroalpha-toxin levels were associated with a positive clinical outcome. Although patients infected with alpha-toxin-producingS. aureusexhibited higher anti-alpha-toxin antibody levels, these levels were not associated with a better clinical outcome in this study.

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Strichartz, G. R., i G. K. Wang. "Rapid voltage-dependent dissociation of scorpion alpha-toxins coupled to Na channel inactivation in amphibian myelinated nerves." Journal of General Physiology 88, nr 3 (1.09.1986): 413–35. http://dx.doi.org/10.1085/jgp.88.3.413.

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The voltage-dependent action of several scorpion alpha-toxins on Na channels was studied in toad myelinated nerve under voltage clamp. These toxins slow the declining phase of macroscopic Na current, apparently by inhibiting an irreversible channel inactivation step and thus permitting channels to reopen from a closed state in depolarized membranes. In this article, we describe the rapid reversal of alpha-toxin action by membrane depolarizations more positive than +20 mV, an effect not achieved by extensive washing. Depolarizations that were increasingly positive and of longer duration caused the toxin to dissociate faster and more completely, but only up to a limiting extent. Repetitive pulses had a cumulative effect equal to that of a single pulse lasting as long as their combined duration. When the membrane of a nonperfused fiber was repolarized, the effects of the toxin returned completely, but if the fiber was perfused during the conditioning procedure, recovery was incomplete and occurred more slowly, as it did at lower applied toxin concentrations. Other alpha-type toxins, from the scorpion Centruroides sculpturatus (IVa) and the sea anemone Anemonia sulcata (ATXII), exhibited similar voltage-dependent binding, though each had its own voltage range and dissociation rate. We suggest that the dissociation of the toxin molecule from the Na channel is coupled to the inactivation process. An equivalent valence for inactivation gating, of less than 1 e per channel, is calculated from the voltage-dependent change in toxin affinity.

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Nagahama, Masahiro. "Vaccines against Clostridium perfringens Alpha-toxin". Current Pharmaceutical Biotechnology 14, nr 10 (31.01.2014): 913–17. http://dx.doi.org/10.2174/1389201014666131226124348.

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Hildebrandt, Jan‐Peter, Sabine Ziesemer i Nils Möller. "Das alpha‐Toxin von Staphylococcus aureus". Biologie in unserer Zeit 49, nr 4 (sierpień 2019): 270–76. http://dx.doi.org/10.1002/biuz.201910681.

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SAKURAI, Jun, Masahiro NAGAHAMA i Sadayuki OCHI. "Action of Clostridium perfringens alpha toxin." Nippon Saikingaku Zasshi 49, nr 5/6 (1994): 719–36. http://dx.doi.org/10.3412/jsb.49.719.

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Matsuda, Asami, Meiji Soe Aung, Noriko Urushibara, Mitsuyo Kawaguchiya, Ayako Sumi, Mayumi Nakamura, Yuka Horino, Masahiko Ito, Satoshi Habadera i Nobumichi Kobayashi. "Prevalence and Genetic Diversity of Toxin Genes in Clinical Isolates of Clostridium perfringens: Coexistence of Alpha-Toxin Variant and Binary Enterotoxin Genes (bec/cpile)". Toxins 11, nr 6 (6.06.2019): 326. http://dx.doi.org/10.3390/toxins11060326.

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Clostridium perfringens (C. perfringens) is responsible for food-borne gastroenteritis and other infectious diseases, and toxins produced by this bacterium play a key role in pathogenesis. Although various toxins have been described for C. perfringens isolates from humans and animals, prevalence of individual toxins among clinical isolates has not yet been well explored. In the present study, a total of 798 C. perfringens clinical isolates were investigated for prevalence of eight toxin genes and their genetic diversity by PCR, nucleotide sequencing, and phylogenetic analysis. Besides the alpha-toxin gene (plc) present in all the isolates, the most common toxin gene was cpe (enterotoxin) (34.2%), followed by cpb2 (beta2 toxin) (1.4%), netB (NetB) (0.3%), and bec/cpile (binary enterotoxin BEC/CPILE) (0.1%), while beta-, epsilon-, and iota-toxin genes were not detected. Genetic analysis of toxin genes indicated a high level of conservation of plc, cpe, and netB. In contrast, cpb2 was revealed to be considerably divergent, containing at least two lineages. Alpha-toxin among 46 isolates was classified into ten sequence types, among which common types were distinct from those reported for avian isolates. A single isolate with bec/cpile harbored a plc variant containing an insertion of 834-bp sequence, suggesting its putative origin from chickens.

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Levistre, R., M. Berguerand, G. Bereziat i J. Masliah. "The cross-regulation of Gi-protein by cholera toxin involves a phosphorylation by protein kinase A". Biochemical Journal 306, nr 3 (15.03.1995): 765–69. http://dx.doi.org/10.1042/bj3060765.

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Pretreatment of alveolar macrophages with cholera toxin inhibits the release of arachidonic acid induced by the chemotactic peptide N-formylmethionyl-leucyl-phenylalanine. The results presented here show that cholera toxin might exert its inhibitory effect through the phosphorylation of Gi alpha by protein kinase A (PKA). (1) Gi-proteins from cells pretreated with cholera toxin showed parallel increases in their sensitivity to ADP-ribosylation by toxins in vitro and in Gi alpha phosphorylation. By contrast, the Gi alpha concentration was unchanged. (2) Cholera toxin pretreatment also decreased the functional activity of Gi, as assessed by the inhibition (80%) of agonist-induced binding of guanosine-5′-[gamma-thio]triphosphate (GTP[gamma S]). (3) These effects of cholera toxin were blocked by a specific PKA inhibitor, N-(2-[methyl-amino]ethyl)-3-isoquinolinesulphonamide dihydrochloride (H8) and mimicked by a cyclic AMP (cAMP) analogue and a phosphatase inhibitor. (4) Gi alpha was also phosphorylated in vitro by the catalytic subunit of PKA. In contrast with other cell systems, the stimulation of protein kinase C seems to have no effect on the sensitivity of Gi to ADP-ribosylation or on its phosphorylation. Therefore, the phosphorylation of Gi-proteins by PKA seems to be the actual target of the negative control of arachidonic acid release via the cAMP-mediated pathway.

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Leung, D. Y., M. Gately, A. Trumble, B. Ferguson-Darnell, P. M. Schlievert i L. J. Picker. "Bacterial superantigens induce T cell expression of the skin-selective homing receptor, the cutaneous lymphocyte-associated antigen, via stimulation of interleukin 12 production." Journal of Experimental Medicine 181, nr 2 (1.02.1995): 747–53. http://dx.doi.org/10.1084/jem.181.2.747.

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T lymphocyte infiltration is a prominent feature of the skin inflammation associated with infections by toxin (superantigen)-secreting Staphylococcus aureus or Streptococcus bacteria. The cutaneous lymphocyte-associated antigen (CLA) has been hypothesized to be a homing receptor (HR) involved in selective migration of memory/effector T cells to the skin. Since the expression of this putative skin-selective HR is known to be under strict microenvironmental control, we sought to determine the effect of staphylococcal and streptococcal toxins on T cell expression of CLA. After in vitro stimulation of peripheral blood mononuclear cells with staphylococcal enterotoxin B, toxic shock syndrome toxin-1, and streptococcal pyrogenic exotoxins A and C, there was a significant increase in the numbers of CLA+ T cell blasts (p < 0.01), but not blasts bearing the mucosa-associated adhesion molecule alpha e beta 7-integrin, compared with T cells stimulated with phytohemaglutinin (PHA) or anti-CD3. Bacterial toxins were also found to specifically induce interleukin (IL) 12 production. More importantly, induction of toxin-induced CLA expression was blocked by anti-IL-12, and the addition of IL-12 to PHA-stimulated T cells induced CLA, but not alpha e beta 7-integrin, expression. These data suggest that bacterial toxins induce the expansion of skin-homing CLA+ T cells in an IL-12-dependent manner, and thus may contribute to the development of skin rashes in superantigen-mediated diseases.

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Niebuhr, Margarete, Merle Gathmann, Helena Scharonow, Diana Mamerow, Susanne Mommert, Hari Balaji i Thomas Werfel. "Staphylococcal Alpha-Toxin Is a Strong Inducer of Interleukin-17 in Humans". Infection and Immunity 79, nr 4 (18.01.2011): 1615–22. http://dx.doi.org/10.1128/iai.00958-10.

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ABSTRACTPatients with atopic dermatitis (AD) are frequently colonized withStaphylococcus aureus, with one-third of isolates producing alpha-toxin. Moreover,S. aureuscolonization is positively correlated with the severity of eczema. Interleukin-17A (IL-17A) has gained attention in diseases associated with chronic skin infections. The aim of this study was to investigate the effects of sublytic alpha-toxin concentrations on IL-17A production. Sublytic alpha-toxin concentrations strongly induced IL-17A in peripheral blood mononuclear cells (PBMCs), isolated CD4+T cells, polarized Th17 cells, and Th17 clones from reactive atopy patch test lesions and blood from AD patients. Alpha-toxin induced IL-17A directly in T cells. The effect of alpha-toxin was further amplified by upregulation of IL-1 in monocytes. In conclusion, higher levels of IL-17A secretion induced by alpha-toxin in the skin partially explain how colonization withS. aureuscan contribute to chronic skin inflammation.

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Eisenhauer, Patricia B., Prasoon Chaturvedi, Richard E. Fine, Andrew J. Ritchie, Jordan S. Pober, Thomas G. Cleary i David S. Newburg. "Tumor Necrosis Factor Alpha Increases Human Cerebral Endothelial Cell Gb3 and Sensitivity to Shiga Toxin". Infection and Immunity 69, nr 3 (1.03.2001): 1889–94. http://dx.doi.org/10.1128/iai.69.3.1889-1894.2001.

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ABSTRACT Hemolytic uremic syndrome (HUS) is associated with intestinal infection by enterohemorrhagic Escherichia coli strains that produce Shiga toxins. Globotriaosylceramide (Gb3) is the functional receptor for Shiga toxin, and tumor necrosis factor alpha (TNF-α) upregulates Gb3 in both human macrovascular umbilical vein endothelial cells and human microvascular brain endothelial cells. TNF-α treatment enhanced Shiga toxin binding and sensitivity to toxin. This upregulation was specific for Gb3 species containing normal fatty acids (NFA). Central nervous system (CNS) pathology in HUS could involve cytokine-stimulated elevation of endothelial NFA-Gb3 levels. Differential expression of Gb3 species may be a critical determinant of Shiga toxin toxicity and of CNS involvement in HUS.

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McNamara, Peter J., Kathy C. Milligan-Monroe, Shirin Khalili i Richard A. Proctor. "Identification, Cloning, and Initial Characterization of rot, a Locus Encoding a Regulator of Virulence Factor Expression in Staphylococcus aureus". Journal of Bacteriology 182, nr 11 (1.06.2000): 3197–203. http://dx.doi.org/10.1128/jb.182.11.3197-3203.2000.

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ABSTRACT A chromosomal insertion of transposon Tn917 partially restores the expression of protease and alpha-toxin activities to PM466, a genetically defined agr-null derivative of the wild-type Staphylococcus aureus strain RN6390. In co-transduction experiments, transposon-encoded erythromycin resistance and a protease- and alpha-toxin-positive phenotype are transferred at high frequency from mutant strains to agr-null strains ofS. aureus. Southern analysis of chromosomal DNA and sequence analysis of DNA flanking the Tn917 insertion site in mutant strains revealed that the transposon interrupted a 498-bp open reading frame (ORF). Similarity searches using a conceptual translation of the ORF identified a region of homology to the known staphylococcal global regulators AgrA and SarA. To verify that the mutant allele conferred the observed phenotype, a wild-type allele of the mutant gene was introduced into the genome of a mutant strain by homologous recombination. The resulting isolates had a restoredagr-null phenotype. Virulence factor gene expression in mutant, restored mutant, and wild-type strains was quantified by measuring alpha-toxin activity in culture supernatant fluids and by Northern analysis of the alpha-toxin transcript. We named this ORFrot (for repressor of toxins) (GenBank accession no.AF189239 ) because of the activity associated withrot::Tn917 mutant strains.

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Rodriguez, Fausto J., Matthew J. Ritter, Craig D. Tauscher i S. Breanndan Moore. "Massive hemolysis secondary to alpha-toxin release". Transfusion 45, nr 2 (luty 2005): 127. http://dx.doi.org/10.1111/j.1537-2995.2004.04206.x.

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Schoepe, Heike, Christian Pache, Axel Neubauer, Heidrun Potschka, Tobias Schlapp, Lothar H. Wieler i Georg Baljer. "Naturally Occurring Clostridium perfringens Nontoxic Alpha-Toxin Variant as a Potential Vaccine Candidate against Alpha-Toxin-Associated Diseases". Infection and Immunity 69, nr 11 (1.11.2001): 7194–96. http://dx.doi.org/10.1128/iai.69.11.7194-7196.2001.

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ABSTRACT Clostridium perfringens mutant strain 121A/91 shows neither enzymatic (phospholipase C) nor hemolytic activity. Nevertheless, the cpa gene and the corresponding alpha-toxin variant are detectable. Vaccination with this genetically constructed alpha-toxin variant, rAT121/91, induces antibodies capable of significantly reducing activities induced by wild-type toxin. Thus, rAT121/91 could be a useful vaccine candidate.

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Coursodon, Christine F., Hien T. Trinh, Michael Mallozzi, Gayatri Vedantam, R. D. Glock i J. G. Songer. "Clostridium perfringens alpha toxin is produced in the intestines of broiler chicks inoculated with an alpha toxin mutant". Anaerobe 16, nr 6 (grudzień 2010): 614–17. http://dx.doi.org/10.1016/j.anaerobe.2010.09.006.

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Ballard, J., A. Bryant, D. Stevens i R. K. Tweten. "Purification and characterization of the lethal toxin (alpha-toxin) of Clostridium septicum." Infection and Immunity 60, nr 3 (1992): 784–90. http://dx.doi.org/10.1128/iai.60.3.784-790.1992.

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Tan, Choo, Kae Tan, Tzu Ng, Si Sim i Nget Tan. "Venom Proteome of Spine-Bellied Sea Snake (Hydrophis curtus) from Penang, Malaysia: Toxicity Correlation, Immunoprofiling and Cross-Neutralization by Sea Snake Antivenom". Toxins 11, nr 1 (23.12.2018): 3. http://dx.doi.org/10.3390/toxins11010003.

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The venom proteome of Hydrophis curtus (synonym: Lapemis hardwickii) from Penang, Malaysia was investigated with nano-electrospray ionization-liquid chromatography tandem mass spectrometry (ESI-LCMS/MS) of the reverse-phase high-performance liquid chromatography (HPLC) venom fractions. Thirty distinct protein forms were identified as toxins from ten families. The three major protein families were phospholipase A2 (PLA2, 62.0% of total venom proteins), three-finger toxin (3FTX, 26.33%) and cysteine-rich secretory protein (CRiSP, 9.00%). PLA2 comprises diverse homologues (11 forms), predominantly the acidic subtypes (48.26%). 3FTX composed of one short alpha-neurotoxin (SNTX, 22.89%) and four long alpha-neurotoxins (LNTX, 3.44%). Both SNTX and LNTX were lethal in mice (intravenous LD50 = 0.10 and 0.24 μg/g, respectively) but the PLA2 were non-lethal (LD50 >1 μg/g). The more abundant and toxic SNTX appeared to be the main driver of venom lethality (holovenom LD50 = 0.20 μg/g). The heterologous Sea Snake Antivenom (SSAV, Australia) effectively cross-neutralized the venom (normalized potency = 9.35 mg venom neutralized per g antivenom) and the two neurotoxins in vivo, with the LNTX being neutralized more effectively (normalized potency = 3.5 mg toxin/g antivenom) than SNTX (normalized potency = 1.57 mg/g). SSAV immunorecognition was strong toward PLA2 but moderate-to-weak toward the alpha-neurotoxins, indicating that neutralization of the alpha-neurotoxins should be further improved.

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Kennedy, Catherine L., Dena Lyras, Leanne M. Cordner, Jody Melton-Witt, John J. Emmins, Rodney K. Tweten i Julian I. Rood. "Pore-Forming Activity of Alpha-Toxin Is Essential for Clostridium septicum-Mediated Myonecrosis". Infection and Immunity 77, nr 3 (12.01.2009): 943–51. http://dx.doi.org/10.1128/iai.01267-08.

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ABSTRACT Clostridium septicum alpha-toxin is a β-barrel pore-forming cytolysin that is functionally similar to aerolysin. Residues important in receptor binding, oligomerization, and pore formation have been identified; however, little is known about the activity of the toxin in an infection, although it is essential for disease. We have now shown that deletion of a small portion of the transmembrane domain, so that the toxin is no longer able to form pores, completely abrogates its ability to contribute to disease, as does replacement of the sole cysteine residue with leucine. However, although previous biochemical and cytotoxicity assays clearly indicated that mutations in residues important in oligomerization, binding, and prepore conversion greatly reduced activity or rendered the toxin inactive, once the mutated toxins were overexpressed by the natural host in the context of an infection it was found they were able to cause disease in a mouse model of myonecrosis. These results highlight the importance of testing the activity of virulence determinants in the normal host background and in an infectious disease context and provide unequivocal evidence that it is the ability of alpha-toxin to form a pore that confers its toxicity in vivo.

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Giese, Bernd, Silvia Dittmann, Kerstin Paprotka, Katja Levin, Annett Weltrowski, Diana Biehler, Thiên-Trí Lâm, Bhanu Sinha i Martin J. Fraunholz. "Staphylococcal Alpha-Toxin Is Not Sufficient To Mediate Escape from Phagolysosomes in Upper-Airway Epithelial Cells". Infection and Immunity 77, nr 9 (29.06.2009): 3611–25. http://dx.doi.org/10.1128/iai.01478-08.

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ABSTRACT Intracellular Staphylococcus aureus has been implicated in the establishment of chronic infections. It is therefore imperative to understand by what means S. aureus is able to survive within cells. Here we use two expression systems with a fluorescent readout to assay alpha-toxin expression and function within phagolysosomes of infected upper-airway epithelial cells: avirulent Staphylococcus carnosus TM300 and phenotypically alpha-toxin-negative S. aureus laboratory strains. Data from CFU recovery assays suggest that the presence of alpha-toxin is not beneficial for the intracellular survival of recombinant Staphylococcus strains. This finding was corroborated by immunofluorescence studies: whereas S. carnosus and S. aureus are able to deliver S. aureus alpha-toxin to lumina of host cell phagolysosomes, the membrane integrity of these organelles was not affected. Alpha-toxin-expressing strains were detected exclusively within lysosome-associated membrane protein 1 (LAMP1)-yellow fluorescent protein (YFP)-positive vesicles. Measurements of intraphagosomal pH illustrated that all infected phagolysosomes acidified regardless of alpha-toxin expression. In contrast, S. aureus expressing Listeria monocytogenes listeriolysin O leads to the breakdown of the phagolysosomal membrane, as indicated by staphylococci that are not associated with LAMP1-YFP-decorated vesicles and that do not reside within an acidic cellular environment. Thus, our results suggest that staphylococcal alpha-toxin is not sufficient to mediate phagolysosomal escape in upper-airway epithelial cells.

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Ellemor, Darren M., Rebecca N. Baird, Milena M. Awad, Richard L. Boyd, Julian I. Rood i John J. Emmins. "Use of Genetically Manipulated Strains of Clostridium perfringens Reveals that Both Alpha-Toxin and Theta-Toxin Are Required for Vascular Leukostasis To Occur in Experimental Gas Gangrene". Infection and Immunity 67, nr 9 (1.09.1999): 4902–7. http://dx.doi.org/10.1128/iai.67.9.4902-4907.1999.

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ABSTRACT A hallmark of gas gangrene (clostridial myonecrosis) pathology is a paucity of leukocytes infiltrating the necrotic tissue. The cause of this paucity most likely relates to the observation of leukocyte aggregates at the border of the area of tissue necrosis, often within the microvasculature itself. Infecting mice with genetically manipulated strains of Clostridium perfringens type A (deficient in either alpha-toxin or theta-toxin production) resulted in significantly reduced leukocyte aggregation when alpha-toxin was absent and complete abrogation of leukocyte aggregation when theta-toxin was absent. Thus, both alpha-toxin and theta-toxin are necessary for the characteristic vascular leukostasis observed in clostridial myonecrosis.

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Eakes, A. T., T. K. Hymer, M. J. Rosenthal, J. Moss i M. S. Katz. "Alterations of adenylyl cyclase-linked G proteins in rat liver during aging". American Journal of Physiology-Endocrinology and Metabolism 270, nr 1 (1.01.1996): E126—E132. http://dx.doi.org/10.1152/ajpendo.1996.270.1.e126.

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beta-Adrenergic stimulation of adenylyl cyclase in rat liver increases during aging. We examined whether this increase is related to alterations in the stimulatory and inhibitory G proteins (Gs and Gi) linked to adenylyl cyclase. Levels of immunoreactive alpha- and beta-subunits of Ga and Gi in liver plasma membranes from 6-, 12-, 18-, and 24-mo-old rats were unchanged with age, as was pertussis toxin-catalyzed [32P]ADP ribosylation of Gi alpha. Cholera toxin-catalyzed [32P]ADP ribosylation of Ga alpha and Gs bioactivity, assessed as reconstitution of adenylyl cyclase activity in S49 cyc- cell membranes, increased two- to threefold between 6 and 12-18 mo, and declined by 24 mo. Recombinant ADP ribosylation factor (ARF) enhanced cholera toxin labeling of Gs alpha at all ages, yet abolished the increase in toxin labeling at 12-18 mo. Auto-ADP ribosylation of the cholera toxin A1 peptide also increased transiently with age. Alteration of Gs alpha, as reflected by increased cholera toxin labeling and Gs bioactivity, may be involved in the regulation of beta-adrenergic-responsive adenylyl cyclase in rat liver during aging. Moreover, changes in endogenous ARF levels could contribute to age differences in cholera toxin labeling of Gs alpha.

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Schepers, T. M., i K. R. McLeish. "Differential cholera-toxin- and pertussis-toxin-catalysed ADP-ribosylation of G-proteins coupled to formyl-peptide and leukotriene B4 receptors". Biochemical Journal 289, nr 2 (15.01.1993): 469–73. http://dx.doi.org/10.1042/bj2890469.

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N-Formylmethionyl-leucyl-phenylalanine (fMet-Leu-Phe) and leukotriene B4 (LTB4) induce disparate second-messenger generation and functional responses in neutrophils and HL-60 granulocytes. Receptors for these chemoattractants couple to a common pool of G-proteins which are substrates for both pertussis-toxin- and cholera-toxin-catalysed ADP-ribosylation. The hypothesis that formyl-peptide and LTB4 receptors induce different receptor-specific conformations of activated G-proteins was tested. The ability of pertussis toxin and cholera toxin to ADP-ribosylate G(i) proteins coupled to formyl-peptide or LTB4 receptors in membranes isolated from HL-60 granulocytes was used to assess the conformational state of the alpha subunits. Cholera-toxin-catalysed ADP-ribosylation of alpha 40 (40 kDa alpha subunit) was inhibited by guanosine 5′-[beta gamma-imido]triphosphate and GDP in a concentration-dependent manner. Addition of fMet-Leu-Phe, but not LTB4, re-established cholera-toxin labelling of alpha 40 in the presence of either guanine nucleotide. In the absence of guanine nucleotides, fMet-Leu-Phe and C5a enhanced cholera-toxin-catalysed labelling of alpha 40, whereas LTB4 and platelet-activating factor had no effect. Preincubation with fMet-Leu-Phe, but not LTB4, inhibited pertussis-toxin labelling of alpha 40 in the presence of guanosine 5′-[gamma-thio]triphosphate and in the absence of guanine nucleotides. Preincubation with fMet-Leu-Phe or LTB4 enhanced pertussis-toxin labelling of alpha 40 in the presence of GDP. These data suggest that activated G(i) proteins coupled to formyl-peptide and LTB4 receptors exist in different conformations determined by the receptor with which they interact.

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Panina-Bordignon, P., X. T. Fu, A. Lanzavecchia i R. W. Karr. "Identification of HLA-DR alpha chain residues critical for binding of the toxic shock syndrome toxin superantigen." Journal of Experimental Medicine 176, nr 6 (1.12.1992): 1779–84. http://dx.doi.org/10.1084/jem.176.6.1779.

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Staphylococcal toxic shock syndrome toxin 1 (TSST-1) binds to major histocompatibility complex class II molecules, and the toxin-class II complexes induce proliferation of T cells expressing V beta 2 sequences. To define the residues involved in TSST-1 binding, a set of transfectants expressing 21 HLA-DR alpha chain mutants were analyzed for their abilities to bind and present TSST-1 and to present an antigenic peptide. Mutations at DR alpha positions 36 and 39 markedly decreased the ability of the DR7 molecule to bind and present TSST-1 but did not affect the ability to present an antigenic peptide. These data indicate that DR alpha residues 36 and 39, predicted to be located on an outer loop, are important in the formation of the TSST-1 binding site on DR molecules.

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Tait, A. Sasha, Monique Dalton, Blandine Geny, Felice D'Agnillo, Michel R. Popoff i Esther M. Sternberg. "The Large Clostridial Toxins from Clostridium sordellii and C. difficile Repress Glucocorticoid Receptor Activity". Infection and Immunity 75, nr 8 (21.05.2007): 3935–40. http://dx.doi.org/10.1128/iai.00291-07.

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ABSTRACT We have previously shown that Bacillus anthracis lethal toxin represses glucocorticoid receptor (GR) transactivation. We now report that repression of GR activity also occurs with the large clostridial toxins produced by Clostridium sordellii and C. difficile. This was demonstrated using a transient transfection assay system for GR transactivation. We also report that C. sordellii lethal toxin inhibited GR function in an ex vivo assay, where toxin reduced the dexamethasone suppression of the proinflammatory cytokine tumor necrosis factor alpha (TNF-α). Furthermore, the glucocorticoid antagonist RU-486 in combination with C. sordellii lethal toxin additively prevented glucocorticoid suppression of TNF-α. These findings corroborate the fact that GR is a target for the toxin and suggest a physiological role for toxin-associated GR repression in inflammation. Finally, we show that this repression is associated with toxins that inactivate p38 mitogen-activated protein kinase (MAPK).

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Salvarani, F. M., Z. I. P. Lobato, R. A. Assis, C. G. R. D. Lima, R. O. S. Silva, P. S. Pires i F. C. F. Lobato. "In vitro evaluation of Clostridium septicum alpha toxoid". Arquivo Brasileiro de Medicina Veterinária e Zootecnia 62, nr 4 (sierpień 2010): 778–83. http://dx.doi.org/10.1590/s0102-09352010000400002.

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Aiming to investigate in vitro alternatives, a test for neutralizing antibody detection using cell culture was developed. This test was more sensitive than previous animal models, allowing for detection of substantially lower alpha toxin and anti-alpha toxin titers. Titers observed during in vivo and in vitro seroneutralization had a correlation of 99.12%, indicating that cell culture is a viable alternative in the evaluation of vaccine potency, screening of vaccinal seeds, and Clostridium septicum alpha toxin titration.

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40

Braunstein, N. S., D. A. Weber, X. C. Wang, E. O. Long i D. Karp. "Sequences in both class II major histocompatibility complex alpha and beta chains contribute to the binding of the superantigen toxic shock syndrome toxin 1." Journal of Experimental Medicine 175, nr 5 (1.05.1992): 1301–5. http://dx.doi.org/10.1084/jem.175.5.1301.

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Class II major histocompatibility complex (MHC) molecules present peptides derived from processed antigen to antigen-specific CD4-positive T cells. In addition, class II molecules bind with high affinity another class of antigens, termed superantigens. T cell stimulation by superantigens depends almost exclusively on the V beta segment expressed by the T cell receptor (TCR). Mapping of the superantigen binding site on class II molecules should provide valuable information on how MHC and TCR molecules interact. Recombinant mouse I-A class II molecules expressed on transfected L cells were analyzed for their ability to bind the toxic shock syndrome toxin 1. Polymorphic residues in the alpha helices of both the alpha and beta chains of I-A contributed to quantitative toxin binding, suggesting that the toxin binds to either a combinatorial or a conformational site on class II MHC molecules.

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Vázquez-Iglesias, Lorena, Borja Estefanell-Ucha, Leticia Barcia-Castro, María Páez de la Cadena, Paula Álvarez-Chaver, Daniel Ayude-Vázquez i Francisco Javier Rodríguez-Berrocal. "A simple electroelution method for rapid protein purification: isolation and antibody production of alpha toxin fromClostridium septicum". PeerJ 5 (22.06.2017): e3407. http://dx.doi.org/10.7717/peerj.3407.

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Clostridium septicumproduces a number of diseases in human and farm animals which, in most of the cases, are fatal without clinical intervention. Alpha toxin is an important agent and the unique lethal virulent factor produced byClostridium septicum.This toxin is haemolytic, highly lethal and necrotizing activities but is being used as an antigen to develop animal vaccines. The aim of this study was to isolate the alpha toxin ofClostridium septicumand produce highly specific antibodies against it. In this work, we have developed a simple and efficient method for alpha toxin purification, based on electroelution that can be used as a time-saving method for purifying proteins. This technique avoids contamination by other proteins that could appear during other protein purification techniques such chromatography. The highly purified toxin was used to produce polyclonal antibodies. The specificity of the antibodies was tested by western blot and these antibodies can be applied to the quantitative determination of alpha toxin by slot blot.

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42

Arana, Angela M., Michael A. Bierdeman, Charles L. Balzli, Aihua Tang, Armando R. Caballero, Rupesh Patel i Richard J. O'Callaghan. "Staphylococcus Alpha-Toxin Action on the Rabbit Iris: Toxic Effects and Their Inhibition". Current Eye Research 40, nr 8 (30.09.2014): 830–38. http://dx.doi.org/10.3109/02713683.2014.959609.

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Keyburn, Anthony L, Scott A. Sheedy, Mark E. Ford, Mark M. Williamson, Milena M. Awad, Julian I. Rood i Robert J. Moore. "Alpha-Toxin of Clostridium perfringens Is Not an Essential Virulence Factor in Necrotic Enteritis in Chickens". Infection and Immunity 74, nr 11 (21.08.2006): 6496–500. http://dx.doi.org/10.1128/iai.00806-06.

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ABSTRACT The Clostridium perfringens alpha-toxin has previously been implicated as the major virulence factor in necrotic enteritis in chickens, although definitive proof has not been reported. In this study an alpha-toxin mutant was constructed in a virulent chicken isolate and shown to retain full virulence in a chicken disease model. These results demonstrated that alpha-toxin is not an essential virulence factor in the pathogenesis of necrotic enteritis in chickens.

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O'Callaghan, R. J., M. C. Callegan, J. M. Moreau, L. C. Green, T. J. Foster, O. M. Hartford, L. S. Engel i J. M. Hill. "Specific roles of alpha-toxin and beta-toxin during Staphylococcus aureus corneal infection." Infection and immunity 65, nr 5 (1997): 1571–78. http://dx.doi.org/10.1128/iai.65.5.1571-1578.1997.

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Blomqvist, L., L. E. Appelgren i M. Thelestam. "Distribution of 3H-labeled staphylococcal alpha-toxin and a toxin fragment in mice." Infection and Immunity 55, nr 8 (1987): 1906–13. http://dx.doi.org/10.1128/iai.55.8.1906-1913.1987.

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Suttorp, N., W. Seeger, E. Dewein, S. Bhakdi i L. Roka. "Staphylococcal alpha-toxin-induced PGI2 production in endothelial cells: role of calcium". American Journal of Physiology-Cell Physiology 248, nr 1 (1.01.1985): C127—C134. http://dx.doi.org/10.1152/ajpcell.1985.248.1.c127.

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Studies in erythrocytes indicate that staphylococcal alpha-toxin generates discrete transmembrane channels with an effective diameter of 2-3 nm. In cultured, confluent, pig pulmonary arterial endothelial cells we studied the triggering of the arachidonic acid cascade and its dependence on calcium influx, possibly through toxin-created pores. In endothelial cells alpha-toxin time dependently (5-30 min) and dose dependently (0.1-8 micrograms/ml) stimulated the release of radiolabeled arachidonic acid and prostacyclin (PGI2) production in similar amounts as the calcium ionophore A23187 (10 microM). Preincubation of alpha-toxin with neutralizing antibodies abolished the effect. The toxin response was strictly dose dependent on extracellular calcium but not on magnesium. The toxin effect was accompanied by an up to 10-fold increased passive permeability of pulmonary arterial endothelial cells for 45Ca. Interference with calcium-calmodulin function (trifluoperazine, W7) dose dependently reduced production of PGI2, but blockers of physiological calcium channels (verapamil, nimodipine, nisoldipine, and diltiazem) did not. In contrast to the effect of the ionophore A23187, the toxin effect was accompanied by a release of potassium, but in neither system was there a release of lactate dehydrogenase. In addition, alpha-toxin but not ionophore-exposed endothelial cells showed an increased passive influx of small radiolabeled markers (45Ca and [3H]sucrose) but not of large markers [( 3H]inulin and [3H]dextran). These data are consistent with the concept that alpha-toxin triggers the arachidonic acid cascade in pulmonary arterial endothelial cells by calcium influx and suggest that this calcium influx may proceed through toxin-created transmembrane channels.

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Li, Jihong, Jianming Chen, Jorge E. Vidal i Bruce A. McClane. "The Agr-Like Quorum-Sensing System Regulates Sporulation and Production of Enterotoxin and Beta2 Toxin by Clostridium perfringens Type A Non-Food-Borne Human Gastrointestinal Disease Strain F5603". Infection and Immunity 79, nr 6 (4.04.2011): 2451–59. http://dx.doi.org/10.1128/iai.00169-11.

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ABSTRACTClostridium perfringenstype A strains producing enterotoxin (CPE) cause one of the most common bacterial food-borne illnesses, as well as many cases of non-food-borne human gastrointestinal disease. Recent studies have shown that an Agr-like quorum-sensing system controls production of chromosomally encoded alpha-toxin and perfringolysin O byC. perfringens, as well as sporulation byClostridium botulinumandClostridium sporogenes. The current study explored whether the Agr-like quorum-sensing system also regulates sporulation and production of two plasmid-encoded toxins (CPE and beta2 toxin) that may contribute to the pathogenesis of non-food-borne human gastrointestinal disease strain F5603. An isogenicagrBnull mutant was inhibited for production of beta2 toxin during vegetative growth and in sporulating culture, providing the first evidence that, inC. perfringens, this system can control production of plasmid-encoded toxins as well as chromosomally encoded toxins. This mutant also showed reduced production of alpha-toxin and perfringolysin O during vegetative growth. Importantly, when cultured in sporulation medium, the mutant failed to efficiently form spores and was blocked for CPE production. Complementation partially or fully reversed all phenotypic changes in the mutant, confirming that they were specifically due to inactivation of theagrlocus. Western blots suggest that this loss of sporulation and sporulation-specific CPE production for theagrBnull mutant involves, at least in part, Agr-mediated regulation of production of Spo0A and alternative sigma factors, which are essential forC. perfringenssporulation.

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Maurer, Katie, Tamara Reyes-Robles, Francis Alonzo, Joan Durbin, Victor J. Torres i Ken Cadwell. "Autophagy Mediates Tolerance to Staphylococcus aureus Alpha-Toxin". Cell Host & Microbe 17, nr 4 (kwiecień 2015): 429–40. http://dx.doi.org/10.1016/j.chom.2015.03.001.

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Sato, Hiroko, Joe Chiba i Yuji Sato. "Monoclonal antibodies against alpha toxin of Clostridium perfringens". FEMS Microbiology Letters 59, nr 1-2 (maj 1989): 173–76. http://dx.doi.org/10.1111/j.1574-6968.1989.tb03104.x.

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Oda, Masataka, Yutaka Terao, Jun Sakurai i Masahiro Nagahama. "Membrane-Binding Mechanism of Clostridium perfringens Alpha-Toxin". Toxins 7, nr 12 (3.12.2015): 5268–75. http://dx.doi.org/10.3390/toxins7124880.

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