Association of Escherichia coli O157:H7 tirpolymorphisms with human infection

Abstract

Background: Emerging molecular, animal model and epidemiologic evidence suggests that Shigatoxigenic Escherichia coli O157:H7 (STEC O157) isolates vary in their capacity to cause human infection and disease. The translocated intimin receptor (tir) and intimin (eae) are virulence factors and bacterial receptor-ligand proteins responsible for tight STEC O157 adherence to intestinal epithelial cells. They represent logical genomic targets to investigate the role of sequence variation in STEC O157 pathogenesis and molecular epidemiology. The purposes of this study were (1) to identify tir and eae polymorphisms in diverse STEC O157 isolates derived from clinically ill humans and healthy cattle (the dominant zoonotic reservoir) and (2) to test any observed tir and eae polymorphisms for association with human (vs bovine) isolate source.

Genome Signatures of Escherichia coli O157:H7 Isolates from the Bovine Host Reservoir

“…A nonrandom distribution of a T255A base substitution within the intimin receptor has been reported, with isolates containing the A allele, to be 34 times more likely to be of bovine rather than human origin, although the physiological relevance of this base substitution that leads to an Asp3Glu substitution in LII strains is not known (14,18). Indeed, the three analyzed bovine strains harbor the A allele, while the human lineage I/II isolate, strain EC508, contains the T allele.…”

“…The sequence data do not allow us to localize the Mu-like insertion for FRIK966 because of contig size and fragmentation, though from our sequence analyses, it is at a site distinct from those found for FRIK2000, Sakai, and Taco John. We detected length polymorphism in the mutator gene Mu-gp35 (ECH7EC4501_3951) due to variable numbers of a characteristic 6-bp perfect repeat (AGCCGA) [5][6][7][8][9][10][11][12][13][14][15] (5-15 represents the range of repeat [AGCCGA] copy numbers in the analyzed Mu-gp35 mutator gene.). The analyzed mutator phage proteins (AE) [5][6][7][8][9][10][11][12][13][14][15] within E. coli O157:H7 range from 128 to 140 aa, while we note that this prophage is otherwise highly conserved and syntenically organized (60).…”

“…To achieve the necessary high phylogenetic resolution and discover branch-specific genome signatures, we applied a multitier approach of SNP-derived genotyping coupled with an analysis of phage content and polymorphisms. SNPs have been identified previously in different subsets of STEC genomes (14,50,56,87); however, the identified SNPs are biased toward strains originating from human outbreaks and thus may be limited in their ability to distinguish genetic STEC subtypes present in cattle (56). We applied a phylogenomic SNP discovery and SNP validation pipeline that was specifically developed for the high-resolution typing of E. coli O157:H7 strains.…”

Genetic Features Differentiating Bovine, Food, and Human Isolates of Shiga Toxin-Producing Escherichia coli O157 in The Netherlands

“…It can be considered paradoxical that the number of human STEC O157 infections is rather low for a pathogen with a low infectious dose when herd-level prevalence is relatively high. This could, at least partly, be explained if only a subset of STEC O157 isolates present in the bovine reservoir are characterized by unique transmissibility and/or virulence characteristics (6).…”

Vaccines for viral and bacterial pathogens causing acute gastroenteritis: Part II: Vaccines forShigella,Salmonella,enterotoxigenicE. coli(ETEC) enterohemorragicE. coli(EHEC) andCampylobacter jejuni

“…164 In fact, polymorphisms have been reported for almost all the effectors coded in LEE and secreted by TTSS. [165][166][167][168] Currently only 2 effective control strategies for livestock have been described. These 2 vaccines against E. coli O157:…”