Lack of expression of bundle-forming pili in some clinical isolates of enteropathogenic Escherichia coli (EPEC) is due to a conserved large deletion in the bfp operon

Bortolini, Mafalda R.

doi:10.1016/s0378-1097(99)00408-5

Cited by 14 publications

(25 citation statements)

References 17 publications

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“…3A). These results indicated that a deletion of the entire bfp operon of EC-3605 occurred, suggesting that it is unable to produce BFP, as described by Bortolini et al (2). In fact, by performing Western blotting with polyclonal antisera raised against E2348/69 BFP, we determined that EC-3605 failed to produce BFP (data not shown).…”

Section: Resultssupporting

confidence: 75%

“…The conflicting results regarding the presence of the EAF plasmid in EC-3605 observed in PCR and Southern blot hybridization suggested a sequence polymorphism between the EAF loci of p3605 and pMAR2. The conflicting results regarding the presence of the bfpA gene in EC-3605 were also observed in PCR with Gunzberg primers and bfpAJY primers, suggesting that the 3Ј end of bfpA 3605 is deleted, as described by Bortolini et al (2), or that the nucleotide sequence of the EP-2 annealing site in bfpA 3605 has low sequence homology with that in bfpA of the prototype EPEC E2348/69, bfpA E2348/69 . In fact, we demonstrated that the entire bfp operon is deleted in EC-3605, and Western blot analysis confirmed that the EC-3605 bfp operon cannot produce BFP.…”

Section: Demonstrated That 14 Orfs Those For Bfpa -G -B -C -U -mentioning

confidence: 93%

“…Recently, Bortolini et al (2) reported that several EPEC strains harbored a truncated bfpA gene and lacked the other bfp operon genes, resulting in a lack of BFP production. The conflicting results regarding the presence of the EAF plasmid in EC-3605 observed in PCR and Southern blot hybridization suggested a sequence polymorphism between the EAF loci of p3605 and pMAR2.…”

Section: Demonstrated That 14 Orfs Those For Bfpa -G -B -C -U -mentioning

confidence: 99%

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Characterization of Atypical Enteropathogenic Escherichia coli Strains Harboring the astA Gene That Were Associated with a Waterborne Outbreak of Diarrhea in Japan

et al. 2003

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The virulence traits of the Escherichia coli strain associated with a waterborne diarrhea outbreak were examined. Forty-one of 75 students (ages 12 to 15) in Akita Prefecture, Japan, showed clinical symptoms. Seven E. coli Ouk:K-:H45 isolates were isolated from the patients as the causative agent of this outbreak. One isolate (EC-3605) showed the presence of E. coli attaching-and-effacing (eaeA) and enteroaggregative E. coli heatstable enterotoxin-1 (astA) genes and the absence of Shiga toxin (stx1 and stx2) genes. A polymorphic enteropathogenic E. coli (EPEC) adherence factor plasmid was detected in EC-3605 with a major structural gene deletion and a regulatory gene frameshift mutation, revealing that EC-3605 represents an atypical EPEC strain harboring the astA gene. The role that atypical EPEC strains harboring the astA gene play in human disease is unclear. Our results, along with those of others, present a possibility that these strains comprise a distinct category of diarrheagenic E. coli and that astA affects the age distribution of atypical-EPEC infection.

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Section: Resultssupporting

confidence: 75%

Section: Demonstrated That 14 Orfs Those For Bfpa -G -B -C -U -mentioning

confidence: 93%

Section: Demonstrated That 14 Orfs Those For Bfpa -G -B -C -U -mentioning

confidence: 99%

See 1 more Smart Citation

Characterization of Atypical Enteropathogenic Escherichia coli Strains Harboring the astA Gene That Were Associated with a Waterborne Outbreak of Diarrhea in Japan

et al. 2003

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“…To confirm this, we designed new primers to target the 5Ј end of bfpA and the IS66-like element. All EAF type 11 strains yielded the ex- pected amplicon, indicating that this plasmid type possesses a similar bfp operon structure as that described by Bortolini and colleagues (10). Aside from the EAF type 11 strains, 17 additional isolates were bfpA negative.…”

Section: Discussionsupporting

confidence: 66%

Molecular Evolution of Typical EnteropathogenicEscherichia coli: Clonal Analysis by Multilocus Sequence Typing and Virulence Gene Allelic Profiling

et al. 2007

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Enteropathogenic Escherichia coli (EPEC) infections are a leading cause of infantile diarrhea in developing nations. Typical EPEC isolates are differentiated from other types of pathogenic E. coli by two distinctive phenotypes, attaching effacement and localized adherence. The genes specifying these phenotypes are found on the locus of enterocyte effacement (LEE) and the EPEC adherence factor (EAF) plasmid. To describe how typical EPEC has evolved, we characterized a diverse collection of strains by multilocus sequence typing (MLST) and performed restriction fragment length polymorphism (RFLP) analysis of three virulence genes (eae, bfpA, and perA) to assess allelic variation. Among 129 strains representing 20 O-serogroups, 21 clonal genotypes were identified using MLST. RFLP analysis resolved nine eae, nine bfpA, and four perA alleles. Each bfpA allele was associated with only one perA allele class, suggesting that recombination has not played a large role in shuffling the bfpA and perA loci between separate EAF plasmids. The distribution of eae alleles among typical EPEC strains is more concordant with the clonal relationships than the distribution of the EAF plasmid types. These results provide further support for the hypothesis that the EPEC pathotype has evolved multiple times within E. coli through separate acquisitions of the LEE island and EAF plasmid.Enteropathogenic E. coli (EPEC) infections are a leading cause of infantile diarrhea in developing nations (31, 37). A key characteristic of EPEC strains is the ability to intimately attach to intestinal epithelial cells and create attaching and effacing (AE) lesions (24). The AE phenotype is specified by genes of the locus of enterocyte effacement (LEE), a ϳ35-kb pathogenicity island located in the bacterial chromosome (23, 41). The LEE island comprises approximately 40 genes and encodes the components of a type III secretion system, various effector molecules, and the intimin adhesin (23,33,68). Intimin plays a crucial role in AE lesion formation (15) and is encoded by the highly polymorphic eae gene (1, 72), which can be divided into periplasmic, transmembrane, and extracellular domains (39). To date, more than 25 major allelic variants of eae have been described (36).Most typical EPEC strains fall into one of two phylogenetically distinct groups or clonal lineages, designated EPEC 1 and EPEC 2 (69), and differ from atypical EPEC and other types of pathogenic E. coli by their ability to form microcolonies on the surface of intestinal epithelial cells (4). This phenotype, termed localized adherence (LA), correlates with the presence of a large virulence plasmid called the EPEC adherence factor (EAF) plasmid (18). The EAF plasmids from different EPEC strains show considerable variation in size (ϳ85 to 110 kb) (48) and, presumably, gene content. Comparison of the complete EAF plasmid sequences from two prototypical EPEC strains (O127:H6 EPEC 1 strain E2348/69 and O111:NM EPEC 2 strain B171) indicates that the EPEC 2 plasmid of B171 carries fewer genes (80 v...

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“…Such strains are phenotypically "atypical," even though they carry probe-detectable EAF plasmids. We therefore hypothesized that the large plasmids of these strains would carry compensatory virulence and/or fitness genes.An atypical O119:H2 EPEC strain, MB80, with a deletion in the bfp operon and inactivating point mutations in the plasmidencoded regulator genes, was selected for study (5,27). Plasmids used, identified, or constructed in the course of the study are listed in Table 1, and standard molecular biology procedures were used throughout (32).…”

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confidence: 99%

A Second Large Plasmid Encodes Conjugative Transfer and Antimicrobial Resistance in O119:H2 and Some Typical O111 Enteropathogenic Escherichia coli Strains

et al. 2007

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A novel and functional conjugative transfer system identified in O119:H2 enteropathogenic Escherichia coli (EPEC) strain MB80 by subtractive hybridization is encoded on a large multidrug resistance plasmid, distinct from the well-described EPEC adherence factor (EAF) plasmid. Variants of the MB80 conjugative resistance plasmid were identified in other EPEC strains, including the prototypical O111:NM strain B171, from which the EAF plasmid has been sequenced. This separate large plasmid and the selective advantage that it confers in the antibiotic era have been overlooked because it comigrates with the virulence plasmid on conventional gels.Enteropathogenic Escherichia coli (EPEC) continues to be a major cause of diarrhea and death, predominantly in developing countries (8,22). During infection, EPEC strains attach intimately to the intestinal epithelium and efface the absorptive microvilli, initiating a complex signaling cascade that ultimately leads to diarrhea by mechanisms that are only partially understood (8). These pathogenic effects manifest as an "attaching and effacing" histopathological hallmark, which is conferred by a large chromosomal island called the locus of enterocyte effacement (LEE). The LEE encodes a virulence gene regulator and a type III secretion system and effectors, as well as the intimin adhesin and its translocated receptor. The LEE is present in all EPEC strains, as well as in enterohemorrhaghic E. coli and some animal pathogens (reviewed in references 8 and 22).EPEC strains are classified as being either typical or atypical based on their ability to form densely packed three-dimensional clusters, or microcolonies, a phenotype known as localized adherence (LA). LA is conferred by a large EPEC adherence factor (EAF) plasmid, associated with virulence in epidemiological and volunteer challenge studies, which is present in all typical EPEC strains and absent or altered in atypical EPEC strains (3,16,25,35). The specific virulence factor responsible for LA is an EAF plasmid-encoded bundleforming pilus (Bfp), which also contributes to antigenicity, autoaggregation, and biofilm formation (3,11,15,20). On a separate region of the EAF plasmid are the perABC genes, encoding the plasmid-encoded regulator (a transcriptional activator for the bfp operon and the LEE, as well as its own promoter) and other virulence loci (9, 19). The EAF plasmid and the LEE are believed to have been acquired by different EPEC lineages in separate horizontal events (30).EAF plasmids from two well-studied EPEC strains have been sequenced. The major difference between the EAF plasmids from isolates E2368/69 (of the EPEC1 lineage [30]) and B171 (representing the EPEC2 lineage [30]), is the presence of conjugative transfer (tra) genes on pMAR7, the E2348/69 EAF plasmid (7). The B171 EAF plasmid, pB171, does not contain tra genes (36), even though at least one earlier paper reported conjugative transfer of pB171 (31). Other than with respect to tra genes, the two sequenced EAF plasmids are highly conserved, and low-resol...

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Lack of expression of bundle-forming pili in some clinical isolates of enteropathogenic Escherichia coli (EPEC) is due to a conserved large deletion in the bfp operon

Cited by 14 publications

References 17 publications

Characterization of Atypical Enteropathogenic Escherichia coli Strains Harboring the astA Gene That Were Associated with a Waterborne Outbreak of Diarrhea in Japan

Characterization of Atypical Enteropathogenic Escherichia coli Strains Harboring the astA Gene That Were Associated with a Waterborne Outbreak of Diarrhea in Japan

Molecular Evolution of Typical EnteropathogenicEscherichia coli: Clonal Analysis by Multilocus Sequence Typing and Virulence Gene Allelic Profiling

A Second Large Plasmid Encodes Conjugative Transfer and Antimicrobial Resistance in O119:H2 and Some Typical O111 Enteropathogenic Escherichia coli Strains

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