The Virulence of Escherichia coli O157:H7 Isolates in Mice Depends on Shiga Toxin Type 2a (Stx2a)-Induction and High Levels of Stx2a in Stool

Hauser, Jocelyn R.; Atitkar, Rama R.; Petro, Courtney D.; Lindsey, Rebecca L.; Strockbine, Nancy; O'Brien, A D; Melton‐Celsa, Angela R.

doi:10.3389/fcimb.2020.00062

Cited by 14 publications

(34 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The fact that we observed more Stx2a translocation than Stx1a is consistent with epidemiological data that Stx2a is more highly associated with the development of HUS than Stx1a [ 3 ]. Although it is unclear why only a small percentage of toxin translocates in the intestinal models, the data are consistent with the low level of HUS (which is the result of systemic intoxication) in people and consistent with the finding of toxin in the feces of animal models infected with STEC [ 30 , 31 ].…”

Section: Discussionsupporting

confidence: 77%

Shiga Toxin (Stx) Type 1a and Stx2a Translocate through a Three-Layer Intestinal Model

Bova

Lamont

Picou

et al. 2023

Toxins

Self Cite

View full text Add to dashboard Cite

Shiga toxins (Stxs) produced by ingested E. coli can induce hemolytic uremic syndrome after crossing the intact intestinal barrier, entering the bloodstream, and targeting endothelial cells in the kidney. The method(s) by which the toxins reach the bloodstream are not fully defined. Here, we used two polarized cell models to evaluate Stx translocation: (i) a single-layer primary colonic epithelial cell model and (ii) a three-cell-layer model with colonic epithelial cells, myofibroblasts, and colonic endothelial cells. We traced the movement of Stx types 1a and 2a across the barrier models by measuring the toxicity of apical and basolateral media on Vero cells. We found that Stx1a and Stx2a crossed both models in either direction. However, approximately 10-fold more Stx translocated in the three-layer model as compared to the single-layer model. Overall, the percentage of toxin that translocated was about 0.01% in the epithelial-cell-only model but up to 0.09% in the three-cell-layer model. In both models, approximately 3- to 4-fold more Stx2a translocated than Stx1a. Infection of the three-cell-layer model with Stx-producing Escherichia coli (STEC) strains showed that serotype O157:H7 STEC reduced barrier function in the model and that the damage was not dependent on the presence of the eae gene. Infection of the three-layer model with O26:H11 STEC strain TW08571 (Stx1a+ and Stx2a+), however, allowed translocation of modest amounts of Stx without reducing barrier function. Deletion of stx2a from TW08571 or the use of anti-Stx1 antibody prevented translocation of toxin. Our results suggest that single-cell models may underestimate the amount of Stx translocation and that the more biomimetic three-layer model is suited for Stx translocation inhibitor studies.

show abstract

Section: Discussionsupporting

confidence: 77%

Shiga Toxin (Stx) Type 1a and Stx2a Translocate through a Three-Layer Intestinal Model

Bova

Lamont

Picou

et al. 2023

Toxins

Self Cite

View full text Add to dashboard Cite

show abstract

“…To better understand the genomic features of clade 8, complete genome sequences are necessary, especially to capture a complete view of the variations in genome structure and the repertoire of MGEs, which are often involved in genome rearrangement and variation in gene content. Therefore, we determined the complete genome sequences of 18 clade 8 strains in this study such that they, together with 17 publicly available closed genomes [20,21,[57][58][59][60][61][62][63][64][65], covered the entire clade 8 population (Fig. 1), allowing fine and systematic comparisons of genome structure and MGE repertoire.…”

Section: Analysis Of Variations In Genome Structure and Mobile Geneti...mentioning

confidence: 99%

Alteration of a Shiga toxin-encoding phage associated with a change in toxin production level and disease severity in Escherichia coli

et al. 2023

View full text Add to dashboard Cite

Among the nine clades of Shiga toxin (Stx)-producing Escherichia coli O157:H7, clade 8 is thought to be highly pathogenic, as it causes severe disease more often than other clades. Two subclades have been proposed, but there are conflicting reports on intersubclade differences in Stx2 levels, although Stx2 production is a risk factor for severe disease development. The global population structure of clade 8 has also yet to be fully elucidated. Here, we present genome analyses of a global clade 8 strain set (n=510), including 147 Japanese strains sequenced in this study. The complete genome sequences of 18 of the 147 strains were determined to perform detailed clade-wide genome analyses together with 17 publicly available closed genomes. Intraclade variations in Stx2 production level and disease severity were also re-evaluated within the phylogenetic context. Based on phylogenomic analysis, clade 8 was divided into four lineages corresponding to the previously proposed SNP genotypes (SGs): SG8_30, SG8_31A, SG8_31B and SG8_32. SG8_30 and the common ancestor of the other SGs were first separated, with SG8_31A and SG8_31B emerging from the latter and SG8_32 emerging from SG8_31B. Comparison of 35 closed genomes revealed the overall structure of chromosomes and pO157 virulence plasmids and the prophage contents to be well conserved. However, Stx2a phages exhibit notable genomic diversity, even though all are integrated into the argW locus, indicating that subtype changes in Stx2a phage occurred from the γ subtype to its variant (γ_v1) in SG8_31A and from γ to δ in SG8_31B and SG8_32 via replacement of parts or almost entire phage genomes, respectively. We further show that SG8_30 strains (all carrying γ Stx2a phages) produce significantly higher levels of Stx2 and cause severe disease more frequently than SG8_32 strains (all carrying δ Stx2a phages). Clear conclusions on SG8_31A and SG8_31B cannot be made due to the small number of strains available, but as SG8_31A (carrying γ_v1 Stx2a phages) contains strains that produce much more Stx2 than SG8_30 strains, attention should also be paid to this SG.

show abstract

“…Except for strain 07–4224, for which only a draft sequence was available [75], the stx 2 suballele could be unambiguously identified either by in silico analysis or PCR interrogation. In 74 % of the 35 strains analysed we detected the most cytotoxic subtype stx 2a [151]; a comparison of Stx 2a -phages is shown in . This suballele is present in all eight sampled Australian ST-820 strains but absent in seven of the 35 ST-223/234/846 strains we examined.…”

Section: Resultsmentioning

confidence: 99%

Pathogenomes and variations in Shiga toxin production among geographically distinct clones of Escherichia coli O113:H21

et al. 2022

View full text Add to dashboard Cite

Infections with globally disseminated Shiga toxin-producing Escherichia coli (STEC) of the O113:H21 serotype can progress to severe clinical complications, such as hemolytic uremic syndrome (HUS). Two phylogeographically distinct clonal complexes have been established by multi locus sequence typing (MLST). Infections with ST-820 isolates circulating exclusively in Australia have caused severe human disease, such as HUS. Conversely, ST-223 isolates prevalent in the US and outside Australia seem to rarely cause severe human disease but are frequent contaminants. Following a genomic epidemiology approach, we wanted to gain insights into the underlying cause for this disparity. We examined the plasticity in the genome make-up and Shiga toxin production in a collection of 20 ST-820 and ST-223 strains isolated from produce, the bovine reservoir, and clinical cases. STEC are notorious for assembly into fragmented draft sequences when using short-read sequencing technologies due to the extensive and partly homologous phage complement. The application of long-read technology (LRT) sequencing yielded closed reference chromosomes and plasmids for two representative ST-820 and ST-223 strains. The established high-resolution framework, based on whole genome alignments, single nucleotide polymorphism (SNP)-typing and MLST, includes the chromosomes and plasmids of other publicly available O113:H21 sequences and allowed us to refine the phylogeographical boundaries of ST-820 and ST-223 complex isolates and to further identify a historic non-shigatoxigenic strain from Mexico as a quasi-intermediate. Plasmid comparison revealed strong correlations between the strains’ featured pO113 plasmid genotypes and chromosomally inferred ST, which suggests coevolution of the chromosome and virulence plasmids. Our pathogenicity assessment revealed statistically significant differences in the Stx2a-production capabilities of ST-820 as compared to ST-223 strains under RecA-induced Stx phage mobilization, a condition that mimics Stx-phage induction. These observations suggest that ST-820 strains may confer an increased pathogenic potential in line with the strain-associated epidemiological metadata. Still, some of the tested ST-223 cultures sourced from contaminated produce or the bovine reservoir also produced Stx at levels comparable to those of ST-820 isolates, which calls for awareness and for continued surveillance of this lineage.

show abstract

The Virulence of Escherichia coli O157:H7 Isolates in Mice Depends on Shiga Toxin Type 2a (Stx2a)-Induction and High Levels of Stx2a in Stool

Cited by 14 publications

References 42 publications

Shiga Toxin (Stx) Type 1a and Stx2a Translocate through a Three-Layer Intestinal Model

Shiga Toxin (Stx) Type 1a and Stx2a Translocate through a Three-Layer Intestinal Model

Alteration of a Shiga toxin-encoding phage associated with a change in toxin production level and disease severity in Escherichia coli

Pathogenomes and variations in Shiga toxin production among geographically distinct clones of Escherichia coli O113:H21

Contact Info

Product

Resources

About