Comparative Analysis of Super-Shedder Strains of @entity526 O157:H7 Reveals Distinctive Genomic Features and a Strongly Aggregative Adherent Phenotype on XXXX Rectoanal Junction Squamous Epithelial Cells.

@entity2772 @entity526 @entity1544 @entity2915 @entity291 @entity6629
Shiga toxin-producing @entity526 O157:H7 (O157) are significant foodborne pathogens and pose a serious threat to public health worldwide. The major reservoirs of O157 are asymptomatic @entity291 which harbor the organism in the terminal recto-anal junction (RAJ). Some colonized animals, referred to as "super-shedders" ( @entity6629 ), are known to shed O157 in exceptionally large numbers (>104 CFU/g of feces). Recent studies suggest that @entity6629 @entity291 play a major role in the prevalence and transmission of O157, but little is known about the molecular mechanisms associated with super-shedding. Whole genome sequence analysis of an @entity6629 O157 strain (SS17) revealed a genome of 5,523,849 bp chromosome with 5,430 open reading frames and two plasmids, pO157 and pSS17, of 94,645 bp and 37,446 bp, respectively. Comparative analyses showed that SS17 is clustered with @entity2772 -associated O157 outbreak strains, and belongs to the lineage I/II, clade 8, D group, and genotype 1, a subgroup of O157 with predicted @entity2915 . A large number of non-synonymous SNPs and other polymorphisms were identified in SS17 as compared with other O157 strains (EC4115, EDL933, Sakai, TW14359), including in key adherence- and virulence-related loci. Phenotypic analyses revealed a distinctive and strongly adherent aggregative phenotype of SS17 on @entity291 @entity1544 ( @entity1544 ) cells that was conserved amongst other @entity6629 isolates. Molecular genetic and functional analyses of defined mutants of SS17 suggested that the strongly adherent aggregative phenotype amongst @entity6629 isolates is LEE-independent, and likely results from a novel mechanism. Taken together, our study provides a rational framework for investigating the molecular mechanisms associated with @entity6629 , and strong evidence that @entity6629 O157 isolates have distinctive features and use a LEE-independent mechanism for hyper-adherence to @entity291 rectal epithelial cells.
