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PubMed1985

Characterization of enterotoxigenic Escherichia coli. Serotypes, enterotoxins, adhesion fimbriae, and the presence of plasmids.

Enterotoxigenic Escherichia coli of human and procine origin were characterized with respect to their O and H antigens, fimbrial antigens, and type of enterotoxin produced. Enterotoxin production was determined by bioassay (infant mice) and enzyme-linked immunoassay (ELISA). The presence of genes coding for the enterotoxins was determined by DNA-DNA hybridization. The number and molecular size of plasmids in the enterotoxigenic strains were determined by gel electrophoresis. Strains with the same serological pattern showed different plasmid profiles and could thereby easily be separated. One strain of porcine origin possessed only one plasmid, but produced both heat-labile enterotoxin and the F4 antigen (formerly K88), which is an unusual combination.

Animals↗

PubMed1975

Escherichia coli enterotoxin. Purification and partial characterization.

Enterotoxin, a diarrheagenic protein elaborated by pathogenic Escherichia coli strains has been isolated from the supernatant of fermenter cultures of E. coli strain P263, a porcine enteropathogen. Purification steps involving Bio-Gel agarose A-5m, Sephadex G-75 chromatography, and preparative isotachophoresis were used in the isolation. The resulting product appears to be pure according to immunoelectrophoretic, disc electrophoretic, ultracentrifugal, and immunologic criteria. The entertoxin has an apparent molecular weight of 102,000 as judged by gel filtration and sodium dodecyl sulfate polyacrylamide gel electrophoresis, and its isoelectric point is 6.90. The isolated product is highly active in inducing experimental diarrhea in adult rabbits and piglets. It also elicits, in small dosage, a marked increase in adenylate cyclase activity in broken cell preparations of cat heart tissue. The enterotoxin activity is acid-labile and is destroyed by heating at 65 degrees for 30 min. It is suggested that the heat-stable enterotoxin material is derived from heat-labile enterotoxin by forming a complex with endotoxin or capsular material present in the culture supernatant.

Adenylyl Cyclases↗

PubMed1990

Superantigens: interaction of staphylococcal enterotoxins with MHC class II molecules.

We have shown that the staphylococcal enterotoxins and TSST specifically bind to MHC class II molecules. This binding to class II molecules is a prerequisite for the function of these bacterial exotoxins as T cell mitogens in vitro. While SEA bound all class II molecules tested with respect to isotype and allotype, the other enterotoxins were limited in binding by the class II isotype. In contrast to conventional antigen, the nature of enterotoxin interactions with MHC enables them to stimulate class I-restricted CD8+ T cells, most likely due to the ability of SEs to engage the T cell receptor based solely on V beta usage. Finally, in addition to activating adjacent T cells, the enterotoxins and TSST can evoke responses from the class II-bearing cells to which they bind. Enterotoxin/TSST effects on cells that bear class II molecule "receptors", in addition to their induction of T cell hormones such as interleukin-2 and interferon-gamma, provide possible explanations for some of the symptomatology seen with these bacterial exotoxins and also implicate MHC class II molecules as signal-transducing receptors.

Antigens, Bacterial↗

PubMed1989

Characterization and cloning of enterotoxin genes of Salmonella typhimurium.

Five of fifty five strains of Salmonella typhimurium of human origin was hybridized with both the LT-A and LT-B gene of Escherichia coli. The remarkably erythromatous and indurated response on rabbit skin and significant elongation of Chinese Hamster Ovary (CHO) cells indicated the production of enterotoxin of these isolates. The Salmonella enterotoxin is heat-labile and is not a secretory product. The LT gene of E. coli was used to analyze the chromosome and plasmid DNA from Salmonella typhimurium strains for toxin gene sequences. Southern blot analysis demonstrated that the toxin gene was located on the plasmid but not on the chromosome. Restriction enzymes BamHI, EcoRI, HindIII and PstI were used to analyze the DNA isolated from salmonella strains Nos.22, 52, 55 and 59. Three DNA fragments with size of 5.2 Kb of strain 22, 5.0 Kb of strain 52 and 8.6 Kb of strain 59 were identified as containing the enterotoxin gene. Plasmid pUC19 was used as the vector to clone these DNA fragments in E. coli. The rabbit skin permeability test indicated that Salmonella enterotoxin could be synthesized at readily detectable levels in these transformed E. coli.

Animals↗

PubMed1989

[The detection of a choleriform thermolabile enterotoxin in clinical strains of Proteus isolated in different infections].

The capacity of Proteus strains, isolated from patients with purulent inflammatory, urological and enteric infections, for the production of choleriform thermolabile enterotoxin was studied by means of the enzyme immunoassay (EIA) with the use of antitoxic serum to Escherichia coli enterotoxin. Out of 125 strains, 27 (21.6%) showed the capacity for producing choleriform thermolabile enterotoxin in EIA experiments. The results thus obtained indicate that EIA techniques can be used, in principle, for detecting the capacity of Proteus for the production of choleriform thermolabile enterotoxin.

Acute Disease↗

PubMed1989

Role of Ca2(+)-calmodulin and protein kinase C in the secretory action of heat-labile enterotoxin of Escherichia coli in mice.

The mucosal-to-serosal and serosal-to-mucosal fluxes of Na+ and Cl- were carried out in control and heat-labile enterotoxin treated mice in the presence or absence of Ca2(+)-ionophore A23187, the activator of Ca2(+)-calmodulin or Phorbol-12-myristate-13-acetate (PMA), the activator of Protein kinase C (PKC) or 1-(5-isoquinolinyl sulphonyl)-2-methyl piperazine (H-7), an inhibitor of PKC. There was net secretion of Na+ and Cl- in experimental group in comparison to net absorption in control group. The addition of ionophore or PMA resulted in net secretion of Na+ and Cl- in control group. In experimental group ionophore increased the net secretion of Na+ and Cl- while, PMA could not cause any change in Na+ and Cl- fluxes in experimental group. Calmodulin activity remained unaltered in heat-labile enterotoxin treated mice as compared to control. H-7, reversed the effects of PMA and heat-labile enterotoxin. These studies demonstrate that heat-labile enterotoxin primarily involves PKC in its action.

Animals↗

PubMed1989

Dissociation between murine spleen cell mitogenic activity of enterotoxin contaminants and anti-tumor activity of staphylococcal protein A.

Soluble staphylococcal protein A (SpA) in the form of high m.w. complexes with IgG has been shown to significantly inhibit the growth of Meth A fibrosarcomas in BALB/c mice. Although SpA reportedly is a potent T cell mitogen that can induce immune cell proliferation and production of humoral factors with anti-tumor activity, it has been suggested that mitogenic enterotoxin contaminants might be responsible for these effects. The purpose of the present study was to investigate the nature of SpA-induced cell proliferation and the relationship between mitogenicity and the anti-tumor effect that we observed in our mouse model. SpA stimulated the proliferation of a mixed population of splenic B and T cells from BALB/c mice, but activity did not require the presence of IgG in the culture medium. Furthermore, mitogenic activity could be inhibited completely by anti-SEA plus anti-SEB, but was unaffected by anti-SpA. HPLC-purified SpA was inactive while the mitogenic factor(s) had the same retention time as authentic enterotoxin and its activity was inhibited by anti-SEA and anti-SEB, but not by anti-SpA. Enterotoxin-free rSpA produced in Escherichia coli had the same IgG binding capacity as the staphylococcal product but was not mitogenic. These data indicate that SEA and SEB completely account for mitogenicity in SpA preparations. In contrast, we found that optimal concentrations of rSpA as well as crude and HPLC purified staphylococcal SpA were equally effective in inhibiting the growth of established Meth A fibrosarcomas demonstrating that SpA is responsible for antitumor activity without any apparent role for enterotoxins.

Animals↗

PubMed1987

[Characteristics of the B subunit of a thermolabile Escherichia coli enterotoxin produced by the A-B+ E. coli strain].

The preparation and identification of B subunit of thermolabile enterotoxin produced by A-B+ gene-containing strain are described. The E. coli strain studied is shown to produce protein identical in its molecular properties and antigenic specificity to B subunit obtained from the whole thermolabile enterotoxin. Partial antigenic affinity between B subunits of thermolabile enterotoxin obtained from different sources and B subunit from cholera enterotoxin has been established in immunochemical studies. Electrophoretic and immunochemical analysis has confirmed the absence of A-subunit admixtures in B-subunit preparation obtained from /A-B+/E. coli strain.

Animals↗

PubMed1977

Enterotoxin antibodies in relation to diarrhoea in Swedish soldiers in Cyprus.

The development of antibodies to Escherichia coli heat-labile enterotoxin (LT) and its relationship to diarrhoea was studied in two Swedish battalions (one in the winter, WB, and one in the summer, SB) of the United Nations Peace-keeping Force in Cyprus. Whereas only 6-15% of the soldiers had detectable levels of anti-LT antibodies in their sera before leaving Sweden, as many as 69% of the SB and 43% of the WB soldiers who developed diarrhoea in Cyprus acquired significant titres of enterotoxin antibodies in their sera (acute phase serum). During the summer, many soldiers without diarrhoea also obtained anti-LT antibodies, whereas no such response was observed in healthy soldiers during the winter. Civilian Turkish Cypriots had positive sera in high frequency (60-66%) during both study periods. Parallel titration of positive sera against E. coli LT and cholera toxin indicated that the enterotoxin-neutralizing antibodies registered were induced by bacteria producing enterotoxin identical or closely related to LT.

Antibodies, Bacterial↗

PubMed1978

Effect of heat stable and heat labile Escherichia coli enterotoxins and cholera toxin in combination with theophylline on unidirectional sodium and chloride flux in the small intestine of weanling swine.

The effect of heat stable and heat labile Escherichia coli enterotoxins or cholera toxin in combination with theophylline on net water, sodium and chloride and unidirectional sodium and chloride fluxes was examined in acute isolated loops of jejunum of weanling swine. The effect of heat stable enterotoxin in combination with theophylline was determined in loops located in the proximal jejunum, while combinations of theophylline and either heat labile enterotoxin or cholera toxin were studied in the distal jejunum. In each situation the addition of theophylline resulted in an additive rather than a synergistic increment of intestinal secretory activity. This study implies that the intestinal adenyl cyclase system and enterotoxin induced intestinal secretion may not be directly related in the swine small intestine.

Animals↗

PubMedDate not supplied

[Electrosyneresis in identification of staphylococcal enterotoxins].

Counterimmunoelectrophoresis adjusted on the ground of proteins tested electrophoretic features, is described as a rapid, simple and specific method for staphylococcal enterotoxins identification. This technique has been applied to either purified enterotoxins A, B, and C1 or crude enterotoxins from 196 E, S6 and 137 strains. Enterotoxin-serum reaction takes place in 25 minutes with formation of a precipitation band. Method sensibility moreover allow to use diluted sera and to detect 2 microgram of the purified toxin.

Counterimmunoelectrophoresis↗

PubMed1981

Effect of chlorpromazine on intestinal secretion mediated by Escherichia coli heat-stable enterotoxin and 8-Br-cyclic GMP in infant mice.

Subcutaneously administered chlorpromazine reduced intestinal fluid accumulation induced by Escherichia coli heat-stable enterotoxin in infant mice. The antisecretory effect of chlorpromazine, although dose related, was, even with high doses, less than that observed with respect to cholera toxin. Whereas 100 micrograms chlorpromazine abolished cholera toxin-induced intestinal secretion almost completely, 500 microgram chlorpromazine (equivalent to 200 microgram/g body wt) lowered secretion induced by heat-stable enterotoxin by only 41%. The effect of chlorpromazine on intestinal secretion was quantitatively similar regardless of whether heat-stable enterotoxin or the cyclic GMP analogue, 8-Br-cyclic GMP, was the secretagogue. This finding, which suggested that the inhibitory effect of chlorpromazine on heat-stable enterotoxin was independent of guanylate cyclase, was confirmed by assaying this enzyme in intestinal homogenates from mice that had been inoculated with chlorpromazine, and also in experiments in which chlorpromazine was added to guanylate cyclase assay mixtures in vitro. Caution is advised before chlorpromazine is routinely adopted for the treatment of all syndromes of watery diarrhea.

Animals↗

PubMed1980

[Characteristics of the heat-stable enterotoxin of NAG vibrios].

Cell-free culture filtrate boiled for 15 minutes has been found to retain its biological activity in various experimental models used for the determination of the toxicogenicity of cholera vibrio filtrates. During gel filtration of the concentrated filrate o. NAG vibrio, strain NO. 9852, through Sephadex G-75 toxic activity could be detected in the free volume of the column, which was indicative of the fact that the molecular weight of the thermostable enterotoxin was about 70,000 daltons and greater. The methods of gel diffusion and aggregated hemagglutination have been used to show that the thermostable enterotoxin of NAG vibrio No. 9852 is immunologically unrelated to cholerogen. Some data obtained in experimental models suggest that the thermostable enterotoxin probably differs from cholera enterotoxin in the mechanism of its action.

Animals↗

PubMed1983

The complete amino acid sequence of staphylococcal enterotoxin C1.

This report presents the complete amino acid sequence of staphylococcal enterotoxin C1. It has a total of 239 amino acids and a calculated Mr = 27,500. Reaction of the native toxin with trypsin produced five peptides, designated A through E. Their structures were determined after further fragmentation with cyanogen bromide, trypsin, and chymotrypsin. Overlap peptides were prepared by cleavage at the two half-cystine residues, and by the reaction of enterotoxin C1 with hydroxylamine. The latter procedure was employed when it was found that one of the three asparaginyl-glycine loci in the toxin is refractory to direct sequencing. The sequence is compared to staphylococcal enterotoxin B. Extensive homology is found, particularly in the carboxyl-terminal region. However, the segment spanned by the disulfide bond in enterotoxin C1 is three residues shorter than the corresponding segment in the B variant.

Amino Acid Sequence↗

PubMed1983

Antigenic and structural variations in the cholera/coli family of enterotoxins.

Recent observations establish the existence of a family of ADP-ribosylating, adenylate cyclase-activating, heat-labile enterotoxins which are structurally, functionally, and immunologically related to the cholera enterotoxin. Despite their overall similarity, it is clear that there are significant structural and immunological differences within the group. These conclusions are supported by extensive experiments comparing the precipitin activity and neutralizing effects of various specific antisera, before and after purification by immunoaffinity chromatography and solid phase immunoaffinity adsorption of common and cross-reactive antibody species, on the various pure enterotoxins. It will be of great importance to determine the full range of the antigenic and structural drift among this family of enterotoxins. The results will have significance in efforts to develop effective broad spectrum antitoxic immunity and also in the development of rapid and reliable techniques for the identifications of enterotoxic enteropathogens.

Antigens, Bacterial↗

PubMed1983

[Biosynthesis and metabolism of prostaglandins in the small intestine of rats exposed to cholera enterotoxin].

The effect of cholera enterotoxin on biosynthesis and metabolism of prostaglandins in the rat small intestine was studied. It was shown that in the course of action of cholera enterotoxin maximal synthesis and metabolism of prostaglandins (PG) was observed within the first 30 minutes after enterotoxin administration into the isolated intestinal loop. It was found that cholera enterotoxin induced, on the one hand, the shift in the correlation of different types of prostaglandins synthetized in vitro and, on the other, differentially activated PG synthesis and metabolism after pretreatment with the PG-synthetase inhibitor indomethacin.

Animals↗

PubMed1984

[Isolation of Salmonella typhimurium enterotoxin in partially purified form and study of its properties].

S. typhimurium enterotoxin, partially purified in accordance with our scheme (salting out with 75% ammonium sulfate, dialysis and gel filtration in a column with Sephadex G-150, followed by electrofocusing), showed enterotoxic activity in the intestinal loop of a rabbit and yielded the positive result in the cutaneous test. S. typhimurium enterotoxin proved to be protein with a molecular weight of 140000 daltons and the isoelectric point equal to 4.4. The biological activity of S. typhimurium enterotoxin was neutralized with homologous antiserum and with antiserum to cholera enterotoxin. Heating the preparation at 75 degrees C for 30 minutes led to a considerable decrease in its enterotoxic activity.

Animals↗

PubMed1980

[Neutralizing activity of antisera to E. coli enterotoxin and a toxoid type preparation].

Antisera obtained as a result of immunization of rabbits with concentrated E. coli enterotoxin, its active fraction or toxoid, had a pronounced toxin-neutralizing activity. At the same time the cytotoxic activity of antisera to the purified fraction was considerably higher than that of the antisera to the concentrated enterotoxin. Such antisera had also a neutralizing effect on thermolabile enterotoxin. The neutralizing activity of antisera to E. coli enterotoxin was clearly manifested in the paw edema test.

Animals↗