scholarly journals Early termination of the Shiga toxin transcript generates a regulatory small RNA

2020 ◽  
Vol 117 (40) ◽  
pp. 25055-25065
Author(s):  
Brandon M. Sy ◽  
Ruiting Lan ◽  
Jai J. Tree
Keyword(s):  
Small Rna ◽  
Shiga Toxin ◽  
High Cell Density ◽  
Shiga Toxins ◽  
General Stress Response ◽  
Short Rnas ◽  
Short Transcript ◽  
Uremic Syndrome ◽  
In Trans ◽  
Late Transcript

Enterohemorrhagic Escherichia coli is a significant human pathogen that causes disease ranging from hemorrhagic colitis to hemolytic uremic syndrome. The latter can lead to potentially fatal renal failure and is caused by the release of Shiga toxins that are encoded within lambdoid bacteriophages. The toxins are encoded within the late transcript of the phage and are regulated by antitermination of the PR′ late promoter during lytic induction of the phage. During lysogeny, the late transcript is prematurely terminated at tR′ immediately downstream of PR′, generating a short RNA that is a byproduct of antitermination regulation. We demonstrate that this short transcript binds the small RNA chaperone Hfq, and is processed into a stable 74-nt regulatory small RNA that we have termed StxS. StxS represses expression of Shiga toxin 1 under lysogenic conditions through direct interactions with the stx1AB transcript. StxS acts in trans to activate expression of the general stress response sigma factor, RpoS, through direct interactions with an activating seed sequence within the 5′ UTR. Activation of RpoS promotes high cell density growth under nutrient-limiting conditions. Many phages utilize antitermination to regulate the lytic/lysogenic switch and our results demonstrate that short RNAs generated as a byproduct of this regulation can acquire regulatory small RNA functions that modulate host fitness.

scholarly journals Induction by Sphingomyelinase of Shiga Toxin Receptor and Shiga Toxin 2 Sensitivity in Human Microvascular Endothelial Cells

2003 ◽  
Vol 71 (2) ◽  
pp. 845-849 ◽  
Author(s):  
T. G. Obrig ◽  
R. M. Seaner ◽  
M. Bentz ◽  
C. A. Lingwood ◽  
B. Boyd ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Shiga Toxin ◽  
Microvascular Endothelial Cells ◽  
Cytotoxic Action ◽  
Ceramide Level ◽  
Shiga Toxins ◽  
Shiga Toxin 2 ◽  
Toxin Receptor ◽  
Uremic Syndrome ◽  
Microvascular Endothelial

ABSTRACT Shiga toxin-producing enterohemorrhagic Escherichia coli is the major cause of acute renal failure in young children. The interaction of Shiga toxins 1 and 2 (Stx1 and Stx2) with endothelial cells is an important step in the renal coagulation and thrombosis observed in hemolytic uremic syndrome. Previous studies have shown that bacterial lipopolysaccharide and host cytokines slowly sensitize endothelial cells to Shiga toxins. In the present study, bacterial neutral sphingomyelinase (SMase) rapidly (1 h) sensitized human dermal microvascular endothelial cells (HDMEC) to the cytotoxic action of Stx2. Exposure of endothelial cells to neutral SMase (0.067 U/ml) caused a rapid increase of intracellular ceramide that persisted for hours. Closely following the change in ceramide level was an increase in the expression of globotriaosylceramide (Gb3), the receptor for Stx2. A rapid increase was also observed in the mRNA for ceramide:glucosyltransferase (CGT), the first of three glycosyltransferase enzymes of the Gb3 biosynthetic pathway. The product of CGT (glucosylceramide) was also increased. In contrast, mRNA for the third enzyme of the pathway, Gb3 synthase, was constitutively produced and was not influenced by SMase treatment of HDMEC. These results describe a rapid response mechanism by which extracellular neutral SMase derived from either bacteria or eukaryotic cells may signal endothelial cells to become sensitive to Shiga toxins.

scholarly journals Characterization of Shiga Toxin 2a Encoding Bacteriophages Isolated From High-Virulent O145:H25 Shiga Toxin-Producing Escherichia coli

2021 ◽  
Vol 12 ◽  
Author(s):  
Silje N. Ramstad ◽  
Yngvild Wasteson ◽  
Bjørn-Arne Lindstedt ◽  
Arne M. Taxt ◽  
Jørgen V. Bjørnholt ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Integration Site ◽  
Severe Disease ◽  
High Sequence Identity ◽  
Shiga Toxins ◽  
Sequence Identity ◽  
Diarrhea Case ◽  
The Usa ◽  
Uremic Syndrome

Shiga toxin-producing Escherichia coli (STEC) may cause severe disease mainly due to the ability to produce Shiga toxins (Stx) encoded on bacteriophages. In Norway, more than 30% of the reported cases with STEC O145:H25 develop hemolytic uremic syndrome (HUS), and most cases, with known travel history, acquired the infection domestically. To describe phage characteristics associated with high virulence, we extracted the Stx2a phage sequences from eight clinical Norwegian O145:H25 STEC to conduct in-depth molecular characterization using long and short read sequencing. The Stx2a phages were annotated, characterized, and compared with previously published Stx2a phages isolated from STEC of different serotypes. The Norwegian O145:H25 Stx2a phages showed high sequence identity (>99%) with 100% coverage. The Stx2a phages were located at the integration site yciD, were approximately 45 kbp long, and harbored several virulence-associated genes, in addition to stx2a, such as nanS and nleC. We observed high sequence identity (>98%) and coverage (≥94%) between Norwegian O145:H25 Stx2a phages and publicly available Stx2a phages from O145:H25 and O145:H28 STEC, isolated from HUS cases in the USA and a hemorrhagic diarrhea case from Japan, respectively. However, low similarity was seen when comparing the Norwegian O145:H25 Stx2a phage to Stx2a phages from STEC of other serotypes. In all the Norwegian O145:H25 STEC, we identified a second phage or remnants of a phage (a shadow phage, 61 kbp) inserted at the same integration site as the Stx2a phage. The shadow phage shared similarity with the Stx2a phage, but lacked stx2a and harbored effector genes not present in the Stx2a phage. We identified a conserved Stx2a phage among the Norwegian O145:H25 STEC that shared integration site with a shadow phage in all isolates. Both phage and shadow phage harbored several virulence-associated genes that may contribute to the increased pathogenicity of O145:H25 STEC.

scholarly journals Contribution and Interaction of Shiga Toxin Genes to Escherichia coli O157:H7 Virulence

Toxins ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 607 ◽  
Author(s):  
Gillian A.M. Tarr ◽  
Taryn Stokowski ◽  
Smriti Shringi ◽  
Phillip I. Tarr ◽  
Stephen B. Freedman ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Population Level ◽  
Escherichia Coli O157 ◽  
Additive Interaction ◽  
Shiga Toxins ◽  
E Coli ◽  
Uremic Syndrome ◽  
Shiga Toxin Genes

Escherichia coli O157:H7 is the predominant cause of diarrhea-associated hemolytic uremic syndrome (HUS) worldwide. Its cardinal virulence traits are Shiga toxins, which are encoded by stx genes, the most common of which are stx1a, stx2a, and stx2c. The toxins these genes encode differ in their in vitro and experimental phenotypes, but the human population-level impact of these differences is poorly understood. Using Shiga toxin-encoding bacteriophage insertion typing and real-time polymerase chain reaction, we genotyped isolates from 936 E. coli O157:H7 cases and verified HUS status via chart review. We compared the HUS risk between isolates with stx2a and those with stx2a and another gene and estimated additive interaction of the stx genes. Adjusted for age and symptoms, the HUS incidence of E. coli O157:H7 containing stx2a alone was 4.4% greater (95% confidence interval (CI) −0.3%, 9.1%) than when it occurred with stx1a. When stx1a and stx2a occur together, the risk of HUS was 27.1% lower (95% CI −87.8%, −2.3%) than would be expected if interaction were not present. At the population level, temporal or geographic shifts toward these genotypes should be monitored, and stx genotype may be an important consideration in clinically predicting HUS among E. coli O157:H7 cases.

Particulate Shiga Toxin 2 in Blood is Associated to the Development of Hemolytic Uremic Syndrome in Children

2019 ◽  
Vol 120 (01) ◽  
pp. 107-120 ◽  
Author(s):  
Maurizio Brigotti ◽  
Xiaohua He ◽  
Domenica Carnicelli ◽  
Valentina Arfilli ◽  
Elisa Porcellini ◽  
...  
Keyword(s):  
Blood Cell ◽  
Hemolytic Uremic Syndrome ◽  
Shiga Toxin ◽  
Time Course ◽  
Hemorrhagic Colitis ◽  
Shiga Toxins ◽  
Circulating Cells ◽  
Shiga Toxin 2 ◽  
Uremic Syndrome ◽  
The Relationship

AbstractHemolytic uremic syndrome (HUS), the leading cause of acute renal failure in children (< 3 years), is mainly related to Shiga toxins (Stx)-producing Escherichia coli (STEC) infections. STEC are confined to the gut resulting in hemorrhagic colitis, whereas Stx are delivered in blood to target kidney and brain, with unclear mechanisms, triggering HUS in 5 to 15% of infected children. Stx were found on circulating cells, free in sera (soluble Stx) or in blood cell-derived microvesicles (particulate Stx), whereby the relationship between these forms of circulating toxins is unclear. Here, we have examined 2,846 children with bloody diarrhea and found evidence of STEC infection in 5%. Twenty patients were enrolled to study the natural course of STEC infections before the onset of HUS. In patients, Stx were found to be associated to circulating cells and/or free and functionally active in sera. In most children, Stx were bound to neutrophils when high amounts of toxins were found in feces. Time-course analysis showed that Stx increased transiently in patients' sera while the decrease of toxin amount on leukocytes was observed. Notably, patients who recovered (85%) displayed different settings than those who developed HUS (15%). The distinctive feature of the latter group was the presence in blood of particulate Stx2 (Stx2 sedimented at g-forces corresponding to 1 μm microvesicles) the day before diagnosis of HUS, during the release phase of toxins from circulating cells. This observation strongly suggests the involvement of blood cell-derived particulate Stx2 in the transition from hemorrhagic colitis to HUS.

scholarly journals Variability in the Occupancy of Escherichia coli O157 Integration Sites by Shiga Toxin-Encoding Prophages

Toxins ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 433
Author(s):  
Scott T. Henderson ◽  
Pallavi Singh ◽  
David Knupp ◽  
David W. Lacher ◽  
Galeb S. Abu-Ali ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Escherichia Coli O157 ◽  
Expected Number ◽  
Shiga Toxins ◽  
Multiple Loci ◽  
Integration Sites ◽  
Uremic Syndrome ◽  
Pcr Assays ◽  
N 93

Escherichia coli O157:H7 strains often produce Shiga toxins encoded by genes on lambdoid bacteriophages that insert into multiple loci as prophages. O157 strains were classified into distinct clades that vary in virulence. Herein, we used PCR assays to examine Shiga toxin (Stx) prophage occupancy in yehV, argW, wrbA, and sbcB among 346 O157 strains representing nine clades. Overall, yehV was occupied in most strains (n = 334, 96.5%), followed by wrbA (n = 213, 61.6%), argW (n = 103, 29.8%), and sbcB (n = 93, 26.9%). Twelve occupancy profiles were identified that varied in frequency and differed across clades. Strains belonging to clade 8 were more likely to have occupied sbcB and argW sites compared to other clades (p < 0.0001), while clade 2 strains were more likely to have occupied wrbA sites (p < 0.0001). Clade 8 strains also had more than the expected number of occupied sites based on the presence of stx variants (p < 0.0001). Deletion of a 20 kb non-Stx prophage occupying yehV in a clade 8 strain resulted in an ~18-fold decrease in stx2 expression. These data highlight the complexity of Stx prophage integration and demonstrate that clade 8 strains, which were previously linked to hemolytic uremic syndrome, have unique Stx prophage occupancy profiles that can impact stx2 expression.

scholarly journals Comparative Analysis of the Abilities of Shiga Toxins 1 and 2 To Bind to and Influence Neutrophil Apoptosis

2006 ◽  
Vol 75 (2) ◽  
pp. 760-765 ◽  
Author(s):  
Michael J. Flagler ◽  
Jane E. Strasser ◽  
Claudia L. Chalk ◽  
Alison A. Weiss
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Human Neutrophils ◽  
Neutrophil Apoptosis ◽  
Shiga Toxins ◽  
Activated Neutrophils ◽  
Life Threatening ◽  
Intestinal Pathogen ◽  
Uremic Syndrome ◽  
Life Threatening Complication

ABSTRACT Hemolytic-uremic syndrome (HUS), the life-threatening complication following infection by the intestinal pathogen Escherichia coli O157:H7, is due to the ability of the pathogen to produce toxins in the Shiga toxin (Stx) family. Activated neutrophils are observed in HUS patients, yet it is unclear whether Stx exerts a direct effect on neutrophils or whether the toxin acts indirectly. The effect of Stx1 and Stx2 on human neutrophils was examined. Neither Stx1 nor Stx2 altered the rate of neutrophil apoptosis. Minimal binding of either toxin to neutrophils was observed, and the toxin was easily eluted from the cells. Stx1 and Stx2 were found to circulate in the plasma of mice following intravenous injection, and both toxins were cleared rapidly from the blood. Together these results suggest that neither Stx1 nor Stx2 interacts directly with neutrophils.

Shiga toxin 2 and lipopolysaccharide cause monocytic THP-1 cells to release factors which activate platelet function

2005 ◽  
Vol 94 (11) ◽  
pp. 1019-1027 ◽  
Author(s):  
Fadila Guessous ◽  
Renata Polanowska-Grabowska ◽  
Tiffany Keepers ◽  
Tom Obrig ◽  
Adrian Gear ◽  
...  
Keyword(s):  
Platelet Function ◽  
Shiga Toxin ◽  
Escherichia Coli O157 ◽  
Monocytic Cells ◽  
Shiga Toxins ◽  
E Coli ◽  
Release Factors ◽  
Serotonin Secretion ◽  
Shiga Toxin 2 ◽  
Uremic Syndrome

SummaryPlatelet and monocyte activation may contribute to hemolytic anemia, thrombocytopenia and renal failure associated with the hemolytic uremic syndrome (HUS) caused by Escherichia coli O157:H7. Since Shiga toxins (Stxs) and lipopolysaccharide (LPS) from this bacterium are implicated in the pathogenesis of HUS, we examined whether stimulation of THP-1 human monocytic cells by Shiga toxin 2 (Stx2) and LPS can lead to the activation of platelet function. We now show that Stx2 caused THP-1 cells to release the chemokines IL-8, MDC, and RANTES and that the presence of LPS further stimulated this release. IL-8 was produced in greatest amount and was an effective co-agonist for inducing platelet aggregation. Primary human monocytes also released large amounts of IL-8 in response to LPS and Stx2. Factors released by THP-1 cells exposed to Stx2 and LPS activated platelet function as evidenced by increased aggregation, serotonin secretion, P-selectin exposure and by the formation of stable platelet-monocyte aggregates. Our data therefore show that monocytes exposed to E. coli-derived Stx2 and LPS release factors which activate platelet function.

Development of candidate vaccines against infection caused by shiga-toxin producing Escherichia coli. Part 1

Bacteriology ◽  
2020 ◽  
Vol 5 (2) ◽  
pp. 56-70
Author(s):  
E.A. Svetoch ◽  
◽  
I.A. Dyatlov ◽  
N.N. Kartsev ◽  
B.V. Eruslanov ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Bacterial Cell ◽  
Farm Animals ◽  
Hemorrhagic Colitis ◽  
Protective Properties ◽  
Shiga Toxins ◽  
Life Threatening ◽  
Uremic Syndrome ◽  
Immunodominant Antigens

Shiga-toxin producing Escherichia coli (STEC) strains cause serious and life-threatening diseases, hemorrhagic colitis (HC) and associated hemolytic uremic syndrome (HUS). Antibacterial etiotropic therapy against these diseases are not recommended. There are no vaccines against human HA and HUS. The review provides materials on the design of various types of candidate vaccines against STEC strains and assessment of their immunogenic and protective properties in experiments on laboratory and farm animals. The prospects for the use of inactivated corpuscular and live (vector) vaccines, lipopolysaccharide vaccines, DNA vaccines and nanovaccines, vaccines based on bacterial cell membranes (ghost), as well as vaccines created by reverse vaccinology methods in practice are considered. Key words: STEC, hemorrhagic colitis, immunodominant antigens, shiga toxins, EspA, EspB, Tir, intimine, IgG, sIgA

Development of candidate vaccines against infection caused by shiga-toxin producing Escherichia coli. Part 2

Bacteriology ◽  
2020 ◽  
Vol 5 (3) ◽  
pp. 47-59
Author(s):  
E.A. Svetoch ◽  
◽  
I.A. Dyatlov ◽  
N.N. Kartsev ◽  
B.V. Eruslanov ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Experimental Studies ◽  
Health Concern ◽  
Secretory Iga ◽  
Hemorrhagic Colitis ◽  
Subunit Vaccines ◽  
Shiga Toxins ◽  
Causative Agents ◽  
Uremic Syndrome

Prevention and treatment of hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS) caused by Shiga-toxin producing Escherichia coli (STEC) continues to be a public health concern. The main reason for the problem is the lack of vaccines and lack of evidence for using of antibacterial etiotropic drugs to treat this infection. A promising scientific approach to create specific agents against STEC infection is the development of subunit recombinant vaccines. The analysis of experimental studies presented in this review shows that effective subunit vaccines against STEC infection can be created on the basis of known immunogenic determinants of HC and HUS causative agents – EspA, EspB, and Tir proteins, intimin, as well as H7 antigen of E. coli O157:H7 and nontoxic proteins of Shiga toxins Stx1 and Stx2 A and B subunits. Using these epitopes, three types of subunit vaccines are designed: antibacterial vaccine, vaccine protecting the macroorganism from systemic intoxication caused by Shiga toxins, and vaccines that simultaneously induce the antibacterial and antitoxic immunity. Since the epitopes listed above are weak immunogenic, to increase their immunogenicity, complex chimeric antigenic structures containing protein inducers are constructed that significantly increase the immune response to target specific epitopes. Mineral adjuvants are also widely used to increase the immunogenicity of STEC epitopes. All three types of created candidate subunit vaccines, at subcutaneous, intramuscular and intranasal application induce production of specific IgG and secretory IgA antibodies in animals and protect them from the infection caused by the STEC strains. Key words: STEC, hemorrhagic colitis, immunodominant antigens, Shiga toxins, EspA, EspB, Tir, intimine, IgG, sIgA

scholarly journals Quiescent complement in nonhuman primates during E coli Shiga toxin-induced hemolytic uremic syndrome and thrombotic microangiopathy

Blood ◽  
2013 ◽  
Vol 122 (5) ◽  
pp. 803-806 ◽  
Author(s):  
Benjamin C. Lee ◽  
Chad L. Mayer ◽  
Caitlin S. Leibowitz ◽  
D. J. Stearns-Kurosawa ◽  
Shinichiro Kurosawa
Keyword(s):  
Hemolytic Uremic Syndrome ◽  
Shiga Toxin ◽  
Complement Activation ◽  
Thrombotic Microangiopathy ◽  
Nonhuman Primates ◽  
Defense Mechanism ◽  
Shiga Toxins ◽  
E Coli ◽  
Key Points ◽  
Uremic Syndrome

Key Points Complement activation is not required for development of thrombotic microangiopathy and HUS induced by EHEC Shiga toxins in nonhuman primates. Complement is an important defense mechanism, and benefits or risks of therapeutic inhibition should be studied further for this infection.

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