title: Further evidence of constrained radiation in the evolution of pathogenic Escherichia coli O157:H7.
abstract: Escherichia coli O157:H7 is a human pathogen that has emerged from its less pathogenic progenitor, E. coli O55:H7, to form the EHEC 1 clade. In its emergence, E. coli O157:H7 formed three distinct clusters, each of which exists today. Sequencing and SNP analysis of Cluster 1 of this clade demonstrated constrained radiation from the cluster founder. Here we investigated the diversity of Cluster 2 strains by sequencing signature SNPs in six strains collected throughout Washington State. Our results suggest that successful Cluster 2 strains have radiated on only two branches from their founder; one of these two branches leads to Cluster 3. Constrained radiation appears to be a common theme among this pathogenic clade.
authors.affiliation: Washington University School of Medicine, Department of Pediatrics, Saint Louis, MO 63110, USA.
authors.forename: Shana R
authors.initials: SR
authors.lastname: Leopold
authors.forename: Nurmohammad
authors.initials: N
authors.lastname: Shaikh
authors.forename: Phillip I
authors.initials: PI
authors.lastname: Tarr
mesh_terms: D015373:Bacterial Typing Techniques; D001483:Base Sequence; D005075:Biological Evolution; D004269:DNA, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000145:classification / Q000235:genetics; D019453:Escherichia coli O157 / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity; D029968:Escherichia coli Proteins / Q000235:genetics*; D019143:Evolution, Molecular; D015870:Gene Expression; D014644:Genetic Variation; D016680:Genome, Bacterial; D023281:Genomics / Q000379:methods; D005838:Genotype; D006801:Humans; D009154:Mutation; D019081:O Antigens / Q000235:genetics; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA; D022603:Shiga Toxins / Q000235:genetics; D014774:Virulence
chemical_list: D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D019081:O Antigens; D022603:Shiga Toxins