Search results for "Enterotoxins"

Incidence of enterotoxigenic staphylococci and their toxins in foods

2002

Of 504 food samples collected from cafeterias, 19 (3.8%) yielded strains of enterotoxigenic staphylococci, and 10 (52.6%), 4 (21.1%), 3 (15.8%), and 2 (10.5%) of these strains produced enterotoxins C (SEC), D (SED), B (SEB), and A (SEA), respectively. Moreover, SEA, SEB, and SEC were isolated from three hamburger samples. Of 181 food samples collected from four restaurants before the implementation of the hazard analysis and critical control point (HACCP) system, 7 (3.9%) were found to contain enterotoxigenic strains, and SED, SEC, and SEA were produced by 4 (57.1%), 2 (28.6%), and 1 (14.3%) of these strains, respectively. One meatball sample with SEC was detected in a restaurant. After the…

Morphological changes in adherent cells induced by Clostridium difficile toxins.

1991

Major histocompatibility complex class II binding site for streptococcal pyrogenic (erythrogenic) toxin A.

1994

Streptococcal pyrogenic exotoxin A (SPEA) is an important pathogenicity factor of group A streptococci. It is a member of the family of „superantigens” produced by Staphylococcus aureus and Streptococcus pyogenes and its T lymphocyte stimulating activity is involved into the pathogenesis of certain diseases caused by pyogenic streptococci. In this study we have produced and characterized recombinant SPEA molecules in Escherichia coli. These molecules are indistinguishable from natural SPEA in both T cell stimulatory and HLA class II binding activities. Human class II molecules are more efficient than mouse class II molecules in presenting SPEA to T cells. In binding tests to major histocomp…

A nonsense mutation abrogates production of a functional enterotoxin A in Clostridium difficile toxinotype VIII strains of serogroups F and X.

1999

Clostridium difficile strains of toxinotype VIII from serogroups F and X are described as toxin B-positive, toxin A-negative (TcdB+ A-), although they harbour almost the entire tcdA gene. To identify the reason for the lack of TcdA detection, we analyzed catalytic and ligand domains of TcdA-1470 of the type strain of serogroup F, strain 1470. Using recombinant fragments, the C-terminal immunodominant ligand domain TcdA3-1470, spanning amino acid residues 1694-2711 (corresponding to VPI 10463 sequence), was detected in Western blots. Similar experiments using the recombinant N-terminal catalytic fragment TcdAc1-2-1470 (amino acid positions 1-544) failed. In addition, this fragment showed no …

Natural and induced apoptosis during lymphocyte development in the axolotl

1999

Lymphocytes apoptosis was characterized in a urodele amphibian, the axolotl, by morphology using electron microscopy and by flow cytometry after propidium iodide staining, as well as by biochemical criteria with the detection of DNA ladders after glucocorticoid treatment. The morphological and biochemical features observed in treated axolotls are in accordance with the criteria of apoptosis found in different models of mammalian lymphocyte programmed cell death. The onset of natural apoptosis was then detected by DNA fragmentation in thymus and in spleen during lymphocyte development and ontogenesis. A typical DNA ladder characteristic of apoptosis is detectable in the thymus as early as 5 …

The Enterotoxin from Clostridium difficile (ToxA) Monoglucosylates the Rho Proteins

1995

The enterotoxin from Clostridium difficile (ToxA) is one of the causative agents of the antibiotic-associated pseudomembranous colitis. In cultured monolayer cells ToxA exhibits cytotoxic activity to induce disassembly of the actin cytoskeleton, which is accompanied by morphological changes. ToxA-induced depolymerization of actin filaments is correlated with a decrease in the ADP-ribosylation of the low molecular mass GTP-binding Rho proteins (Just, I., Selzer, J., von Eichel-Streiber, C., and Aktories, K. (1995) J. Clin. Invest. 95, 1026-1031). Here we report on the identification of the ToxA-induced modification of Rho. Applying electrospray mass spectrometry, the mass of the modification…

Clostridium difficile toxin A induces expression of the stress-induced early gene product RhoB.

2004

Clostridium difficile toxin A monoglucosylates the Rho family GTPases Rho, Rac, and Cdc42. Glucosylation leads to the functional inactivation of Rho GTPases and causes disruption of the actin cytoskeleton. A cDNA microarray revealed the immediate early gene rhoB as the gene that was predominantly up-regulated in colonic CaCo-2 cells after treatment with toxin A. This toxin A effect was also detectable in epithelial cells such as HT29 and Madin-Darby canine kidney cells, as well as NIH 3T3 fibroblasts. The expression of RhoB was time-dependent and correlated with the morphological changes of cells. The up-regulation of RhoB was approximately 15-fold and was based on the de novo synthesis of …

B subunits of cholera toxin and thermolabile enterotoxin of Escherichia coli have similar adjuvant effect as whole molecules on rotavirus 2/6-VLP spe…

2015

The purpose of this study was to evaluate the adjuvant effect of the B subunits of cholera toxin (CT) and the thermolabile enterotoxin of Escherichia coli (LT) by the intrarectal route of immunization and compare them to the whole molecules CT and LT-R192G, a non toxic mutant of LT, using 2/6-VLP as an antigen, in mice. All molecules induced similar antigen specific antibody titers in serum and feces, whereas different T cell profiles were observed. CTB and LTB, conversely to CT and LT-R192G, did not induce detectable production of IL-2 by antigen specific T cells. Moreover, CTB, conversely to LT-R192G, CT and LTB, did not induce antigen specific CD4+CD25+Foxp3- and Foxp3+ T cells, thus sho…

Single-chain variable fragment (scFv) antibodies against rotavirus NSP4 enterotoxin generated by phage display.

2004

The rotavirus non-structural NSP4 protein causes membrane destabilization as well as an increase in intracellular calcium levels in eukaryotic cells and induces diarrhea in young mice, acting as a viral enterotoxin. In this study the phage display technique was used to generate a panel of single-chain variable fragment (scFv) antibodies specific for the NSP4 protein of the human rotavirus strain Wa from a human semi-synthetic scFv library. After several rounds of panning and selection on NSP4 adsorbed to polystyrene tubes, individual scFv were isolated and characterised by fingerprinting and by sequencing the VH and VL genes. The isolated scFv antibodies specifically recognize NSP4 in enzym…

Different profile and distribution of antigen specific T cells induced by intranasal and intrarectal immunization with rotavirus 2/6-VLP with and wit…

2013

International audience; In this study, we compared both the profile and distribution of antigen specific primed T cells after intrarectal (IR) and intranasal (IN) immunization with rotavirus (RV) 2/6-VLP, alone or in the presence of LT-R192G, in order to highlight the differences between the two routes and the impact of the adjuvant. Adult BALB/c mice were immunized once with 2/6-VLP with or without adjuvant and the T cell response was analyzed in lymphoid tissues after in vitro restimulation with the antigen. IN, but not IR, immunization of mice with 2/6-VLP alone induced antigen-specific IL-10 and IL-17 secreting T cells. IL-10-, in contrast to IL-17-, secreting T cells did not migrate to…