A Single-Step Purification and Molecular Characterization of Functional Shiga Toxin 2 Variants from Pathogenic Escherichia coli

ABSTRACTShiga toxin-producing Escherichia coli (STEC) is a bacterial pathogen that cause diarrhea and severe human diseases. Its principal virulence factor are the Shiga toxins Stx1 and Stx2 which have been identified diverse subtypes considered to be responsible for severe complications of STEC infection. These toxins are encoded in temperate bacteriophages and their expression is linked to phage lithic cycle, which is regulated by late genes and the Q anti-terminator protein. The aim of this study was to characterize biologically and molecularly STEC strains encoding stx2 gene isolated from cattle feces in Colombia. We selected six STEC strains, which were evaluated its Stx production, the Stx2 subtypes, induction of the lithic cycle of bacteriophages and its late region. The results evidenced two highlighted strains with high levels of Stx production and induction of the lithic cycle, compared with the others. Likewise, the strains evaluated showed three Stx2 subtypes: Stx2a, Stx2c, and Stx2d. Regarding the late region, most of the strains carried the qO111 allele and only one strain showed differences in the ninG gene. Although the sample was limited, variability was observed in the Stx production assay, induction of the lithic cycle, Stx2 subtypes and late region of the phages, which could indicate the diversity of the phages carrying STEC strains in Colombia.

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Detection and molecular characterization of Shiga toxin producing Escherichia coli (STEC) autoagglutinating adhesion gene (saa) from piglets in Mizoram

Veterinary World ◽

10.14202/vetworld.2014.373-376 ◽

2014 ◽

Vol 7 (6) ◽

pp. 373-376

Author(s):

J. L. Kataria ◽

T. K. Dutta ◽

P. Roychoudhury ◽

J. G. Tiwari

Keyword(s):

Escherichia Coli ◽

Molecular Characterization ◽

Shiga Toxin

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Escherichia coli Serogroup O107/O117 Lipopolysaccharide Binds and Neutralizes Shiga Toxin 2

Journal of Bacteriology ◽

10.1128/jb.186.16.5506-5512.2004 ◽

2004 ◽

Vol 186 (16) ◽

pp. 5506-5512 ◽

Cited By ~ 25

Author(s):

Shantini D. Gamage ◽

Colleen M. McGannon ◽

Alison A. Weiss

Keyword(s):

Escherichia Coli ◽

Shiga Toxin ◽

Biochemical Characterization ◽

Vero Cells ◽

Systemic Complications ◽

E Coli ◽

Major Virulence Factor ◽

Shiga Toxin 2 ◽

Type Strains

ABSTRACT The AB5 toxin Shiga toxin 2 (Stx2) has been implicated as a major virulence factor of Escherichia coli O157:H7 and other Shiga toxin-producing E. coli strains in the progression of intestinal disease to more severe systemic complications. Here, we demonstrate that supernatant from a normal E. coli isolate, FI-29, neutralizes the effect of Stx2, but not the related Stx1, on Vero cells. Biochemical characterization of the neutralizing activity identified the lipopolysaccharide (LPS) of FI-29, a serogroup O107/O117 strain, as the toxin-neutralizing component. LPSs from FI-29 as well as from type strains E. coli O107 and E. coli O117 were able bind Stx2 but not Stx1, indicating that the mechanism of toxin neutralization may involve inhibition of the interaction between Stx2 and the Gb3 receptor on Vero cells.

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Multilocus genotypic characterization of Escherichia coli O157:H7 recovered from food sources

Epidemiology and Infection ◽

10.1017/s0950268814003197 ◽

2014 ◽

Vol 143 (11) ◽

pp. 2367-2372 ◽

Cited By ~ 3

Author(s):

M. M. ELHADIDY ◽

W. F. ELKHATIB

Keyword(s):

Escherichia Coli ◽

Genetic Markers ◽

Shiga Toxin ◽

Insertion Site ◽

Multivariable Analysis ◽

Food Sources ◽

Pathogenic Potential ◽

Genotypic Characterization ◽

Shiga Toxin 2

SUMMARYEscherichia coli O157:H7 strains (n = 33) recovered from different food sources in Egypt were characterized using molecular assays to identify strain genotypes associated with various levels of pathogenic potential. Genotypic characterization included: lineage-specific polymorphism assay (LSPA-6), Shiga-toxin-encoding bacteriophage insertion site assay (SBI), clade 8 typing, Tir (A255 T) polymorphism, and variant analysis of Shiga toxin 2 gene (Stx2a and Stx2c), and anti-terminator Q genes (Q933 and Q21). Genotypes LI/II (76%), SBI 1 (60·6%), clade 8 (69·7%), Tir (255 T) (72·7%) and Stx2c (45·5%) were found to be significantly more frequent compared to other genetic markers in the strains analysed. Multivariable analysis revealed a significant association between LPSA-6 and clade types as well as Tir (A255 T). To the best of our knowledge, this is the first study to report the characterization of these genetic markers in E. coli O157:H7 strains in the Middle East and Africa.

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