<i>rhs</i>
            Genes Are Potential Markers for Multilocus Sequence Typing of
            <i>Escherichia coli</i>
            O157:H7 Strains

Liu, Kuanqing; Knabel, Stephen J.; Dudley, Edward G.

doi:10.1128/aem.00859-09

Cited by 24 publications

(33 citation statements)

References 43 publications

(73 reference statements)

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“…Moreover, a strong association between clade 8 and lineages I/II was observed where all clade 8 strains were represented by lineage I/II and were absent in the other lineages. A similar observation was reported by other studies Liu et al, 2009;Hartzell et al, 2011) supporting the previous postulation that within lineage I/II, certain clades are more virulent and are responsible for more frequent and severe diseases than others Vanaja et al, 2010). Furthermore, these findings provided more evidence that clade 8 might be used as a useful surrogate genotype for the highly virulent lineage I/II strains.…”

Section: Discussionsupporting

confidence: 79%

“…Our results revealed that the remaining lineage I/II strains were representatives of clades 5, 6 and 7. Clade 6 and 7 strains have been previously noted among US O157 strains that were designated to be represented by lineage I/II (Liu et al, 2009). To the best of our knowledge, this study provides the first evidence of clade 5 association with lineage I/II.…”

Section: Discussionsupporting

confidence: 48%

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Genetic diversity of Shiga toxin-producing Escherichia coli O157 : H7 recovered from human and food sources

et al. 2015

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The aim of this study was to identify an epidemiological association between Shiga toxinproducing Escherichia coli O157 : H7 strains associated with human infection and with food sources. Frequency distributions of different genetic markers of E. coli O157 : H7 strains recovered from human and food sources were compared using molecular assays to identify E. coli O157 : H7 genotypes associated with variation in pathogenic potential and host specificity. Genotypic characterization included: lineage-specific polymorphism assay (LSPA-6), clade typing, tir (A255T) polymorphism, Shiga toxin-encoding bacteriophage insertion site analysis and variant analysis of Shiga toxin 2 gene (stx 2a and stx 2c ) and antiterminator Q genes (Q 933 and Q 21 ). The intermediate lineage (LI/II) dominated among both food and human strains. Compared to other clades, clades 7 and 8 were more frequent among food and human strains, respectively. The tir (255T) polymorphism occurred more frequently among human strains than food strains. Q 21 and Q 933+Q21 were found at significantly higher frequencies among food and human strains, respectively. Moreover, stx 2a and stx 2a+c were detected at significantly higher frequencies among human strains compared to food strains. Bivariate analysis revealed significant concordance (P,0.05) between the LSPA-6 assay and the other typing methods. Multivariable regression Abbreviations: HP, hairpin; HUS, haemolytic uraemic syndrome; LSPA-6, lineage-specific polymorphism assay; SBI, Shiga toxin bacteriophage insertion; STEC, Shiga toxin-producing Escherichia coli; stx 1 , Shiga toxin 1; stx 2 , Shiga toxin 2.Five supplementary tables are available with the online Supplementary Material.

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Section: Discussionsupporting

confidence: 79%

Section: Discussionsupporting

confidence: 48%

Genetic diversity of Shiga toxin-producing Escherichia coli O157 : H7 recovered from human and food sources

et al. 2015

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“…The clade 8_rhsA assay targets one of the single nucleotide polymorphisms (SNPs) possible in the rhsA gene (SNP position 3468) (29). A PCR fragment with a length of 635 bp was generated with the rhsA primers indicated in Table 1.…”

Section: Methodsmentioning

confidence: 99%

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

et al. 2012

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The frequency of Escherichia coli O157 genotypes among bovine, food, and human clinical isolates from The Netherlands was studied. Genotyping included the lineage-specific polymorphism assay (LSPA6), the Shiga-toxin-encoding bacteriophage insertion site assay (SBI), and PCR detection and/or subtyping of virulence factors and markers [stx1, stx 2a /stx 2c , q21/Q933, tir(A255T), and rhsA(C3468G)]. LSPA6 lineage II dominated among bovine isolates (63%), followed by lineage I/II (35.6%) and lineage I (1.4%). In contrast, the majority of the human isolates were typed as lineage I/II (77.6%), followed by lineage I (14.1%) and lineage II (8.2%). Multivariate analysis revealed that the tir(A255T) SNP and the stx 2a /stx 2c gene variants were the genetic features most differentiating human from bovine isolates. Bovine and food isolates were dominated by stx 2c (86.4% and 65.5%, respectively). Among human isolates, the frequency of stx 2c was 36.5%, while the frequencies of stx 2a and stx 2a plus stx 2c were 41.2% and 22.4%, respectively. Bovine isolates showed equal distribution of tir(255A) (54.8%) and tir(255T) (45.2%), while human isolates were dominated by the tir(255T) genotype (92.9%). LSPA6 lineage I isolates were all genotype stx 2c and tir(255T), while LSPA6 lineage II was dominated by tir(255A) (86.4%) and stx 2c (90.9%). LSPA6 lineage I/II isolates were all genotype tir(255T) but showed more variation in stx 2 types. The results support the hypothesis that in The Netherlands, the genotypes primarily associated with human disease form a minor subpopulation in the bovine reservoir. Comparison with published data revealed that the distribution of LSPA6 lineages among bovine and human clinical isolates differs considerably between The Netherlands and North America. Shiga toxin-producing Escherichia coli (STEC) O157 is considered a serious pathogen due to its low infectious dose, the severe clinical symptoms (especially among children), and the potential for food-and waterborne outbreaks (7,22,35). STEC O157 can be transmitted to humans by direct contact with the ruminant reservoir or indirectly via ingestion of contaminated food or water (33). STEC O157 has several virulence genes that play a crucial role in the development of clinical symptoms. These include the Shiga toxin genes 1 and 2 (stx 1 and stx 2 ), several genes located on the chromosomal locus of enterocyte effacement (LEE), which codes for a specialized epithelium attachment system responsible for the characteristic attaching and effacing (A/E) phenotype, and (putative) virulence factors encoded on various genomic pathogenicity islands (20,25).In The Netherlands, the prevalences of STEC O157 at the herd level are on average 8% for dairy herds and 13% for veal herds (2), with seasonal peaks from 30% to 70% during the summer months (12,19). The notification rates of STEC O157 disease cases in The Netherlands (including outbreaks) for 2007, 2008, and 2009 were 0.50, 0.27, and 0.34 cases per 100,000 inhabitants per year, respectively (14). It can be cons...

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“…This structure suggests that rhs genes are composites formed by the insertion of horizontally transferred core-extension sequences (2,3). Rhs-CT polymorphism is extensive, and different strains of a given species typically contain a distinct complement of rhs alleles (2,3,5). Rhs are distributed throughout β-, γ-, and δ-proteobacteria, and genes encoding more distantly related YD-peptide repeat proteins are found in Gram-positive bacteria, some fungi, and higher metazoans through the vertebrates (6)(7)(8).…”

mentioning

confidence: 99%

Rhs proteins from diverse bacteria mediate intercellular competition

Koskiniemi¹,

Lamoureux²,

Nikolakakis³

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

363

437

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Rearrangement hotspot (Rhs) and related YD-peptide repeat proteins are widely distributed in bacteria and eukaryotes, but their functions are poorly understood. Here, we show that Gram-negative Rhs proteins and the distantly related wall-associated protein A (WapA) from Gram-positive bacteria mediate intercellular competition. Rhs and WapA carry polymorphic C-terminal toxin domains (Rhs-CT/WapA-CT), which are deployed to inhibit the growth of neighboring cells. These systems also encode sequence-diverse immunity proteins (RhsI/WapI) that specifically neutralize cognate toxins to protect rhs + /wapA + cells from autoinhibition. RhsA and RhsB from Dickeya dadantii 3937 carry nuclease domains that degrade target cell DNA. D. dadantii 3937 rhs genes do not encode secretion signal sequences but are linked to hemolysin-coregulated protein and valine-glycine repeat protein G genes from type VI secretion systems. Valine-glycine repeat protein G is required for inhibitor cell function, suggesting that Rhs may be exported from D. dadantii 3937 through a type VI secretion mechanism. In contrast, WapA proteins from Bacillus subtilis strains appear to be exported through the general secretory pathway and deliver a variety of tRNase toxins into neighboring target cells. These findings demonstrate that YD-repeat proteins from phylogenetically diverse bacteria share a common function in contact-dependent growth inhibition.

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rhs Genes Are Potential Markers for Multilocus Sequence Typing of Escherichia coli O157:H7 Strains

Cited by 24 publications

References 43 publications

Genetic diversity of Shiga toxin-producing Escherichia coli O157 : H7 recovered from human and food sources

Genetic diversity of Shiga toxin-producing Escherichia coli O157 : H7 recovered from human and food sources

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

Rhs proteins from diverse bacteria mediate intercellular competition

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