Detection of a Novel Virulence Gene and a Salmonella Virulence Homologue Among Escherichia coli Isolated from Broiler Chickens

Morales, Cesar A.; Lee, Margie D.; Hofacre, Charles L.; Maurer, John J.

doi:10.1089/fpd.2004.1.160

Cited by 51 publications

(33 citation statements)

References 29 publications

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“…This (12,20,23,24,28,29,36,37,39,41,48,49). However, ColBM plasmids are an exception to this rule, and the sequence of pAPEC-O1-ColBM provides interesting insights into the possible evolution of Ftype plasmids and also into the nature of plasmid-mediated APEC virulence.…”

Section: Discussionmentioning

confidence: 99%

“…The "conserved" portion of the cluster contains four iron transport and acquisition systems, including the aerobactin and salmochelin siderophore systems and the sit and eit ABC transporter systems (23). Additionally, the conserved portion of the cluster contains the increased serum survival gene (iss), previously implicated in increased virulence and serum resistance (2); hlyF, a gene encoding a putative avian E. coli hemolysin (29); ompT, an outer membrane protease (36); the RepFIB replicon (14); and portions of the ColV operon, including cvaA and the 5Ј portion of cvaB, both ColV export genes (15). Interestingly, the split in gene prevalence between the conserved and variable portions of this virulence cluster occurs within the cvaB gene of the ColV operon (23).…”

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confidence: 99%

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Complete DNA Sequence of a ColBM Plasmid from Avian Pathogenic Escherichia coli Suggests that It Evolved from Closely Related ColV Virulence Plasmids

2006

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Avian pathogenic Escherichia coli (APEC), an extraintestinal pathogenic E. coli causing colibacillosis in birds, is responsible for significant economic losses for the poultry industry. Recently, we reported that the APEC pathotype was characterized by possession of a set of genes contained within a 94-kb cluster linked to a ColV plasmid, pAPEC-O2-ColV. These included sitABCD, genes of the aerobactin operon, hlyF, iss, genes of the salmochelin operon, and the 5 end of cvaB of the ColV operon. However, the results of gene prevalence studies performed among APEC isolates revealed that these traits were not always linked to ColV plasmids. Here, we present the complete sequence of a 174-kb plasmid, pAPEC-O1-ColBM, which contains a putative virulence cluster similar to that of pAPEC-O2-ColV. These two F-type plasmids share remarkable similarity, except that they encode the production of different colicins; pAPEC-O2-ColV contains an intact ColV operon, and pAPEC-O1-ColBM encodes the colicins B and M. Interestingly, remnants of the ColV operon exist in pAPEC-O1-ColBM, hinting that ColBM-type plasmids may have evolved from ColV plasmids. Among APEC isolates, the prevalence of ColBM sequences helps account for the previously observed differences in prevalence between genes of the "conserved" portion of the putative virulence cluster of pAPEC-O2-ColV and those genes within its "variable" portion. These results, in conjunction with Southern blotting and probing of representative ColBM-positive strains, indicate that this "conserved" cluster of putative virulence genes is primarily linked to F-type virulence plasmids among the APEC isolates studied.Avian pathogenic Escherichia coli (APEC), an extraintestinal pathogenic E. coli causing colibacillosis in birds, is responsible for significant economic losses for the poultry industry (7), yet the virulence mechanisms underlying APEC virulence are imperfectly understood. Recent studies have sought to define the APEC pathotype and have shown that several genes occur frequently among APEC, regardless of the avian host species or lesion of origin (12,36,37). Many of these genes that are characteristic of the APEC pathotype are linked to large plasmids, and many of these plasmids encode production of the bacteriocin ColV (9, 23, 36, 37), leading to their being termed ColV plasmids.ColV plasmids have long been recognized for their association with E. coli virulence (43, 51, 54). However, ColV production, the namesake trait of ColV plasmids, does not appear to contribute to the disease-causing abilities of E. coli (35), suggesting that other ColV plasmid-linked traits might be responsible for ColV plasmids' association with virulence. Indeed, we have recently completed the first sequence of a 180-kb ColV plasmid, revealing the presence of a 94-kb cluster of putative virulence genes (23). Based on studies of the prevalence of the genes of this putative virulence cluster among avian E. coli isolates, it appears that the cluster contains a "conserved" region, with its genes occurring in ...

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Complete DNA Sequence of a ColBM Plasmid from Avian Pathogenic Escherichia coli Suggests that It Evolved from Closely Related ColV Virulence Plasmids

2006

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“…There were trials to deliver the antigen using surface display and secretion of ClyA (9,10). In this work, 193-aa S1E epitope from SARSCoV S protein was chosen as a cargo antigen because this has been well characterized as a receptor binding domain (22) and vaccine candidate (14). The recombinant protein…”

Section: Discussionmentioning

confidence: 99%

“…However, any bacteria expressing ClyA-S1E did not show cell death at all in this condition (panels 3 and 4). ClyA induces apoptosis as well as necrosis (22). Apoptosis causes DNA fragmentation in the genome (15) and is induced by Salmonella infection (23).…”

Section: Hemolytic and Cytotoxic Activities Of Clya-s1e Expressed In mentioning

confidence: 99%

The Bacterial Surface Expression of SARS Viral Epitope using Salmonella typhi Cytolysin A

et al. 2009

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The cytolysin A (ClyA) is a 34 kDa pore-forming cytotoxic protein and expressed by some enteric bacteria including Salmonella typhi. This toxin is transported on the bacterial surface and secreted without posttranslational modification. Using the surface display of ClyA, the expression vectors for 193-aa immunogenic antigen of spike protein (termed S1E) from severe acute respiratory syndrome coronavirus (SARS-CoV) were constructed. The vectors carried a gene encoding S. typhi ClyA conjugated to S1E at the C terminus (termed ClyA-S1E) and asd gene in pGEM-T and pBR322, named pGApLCS1E and pBApLCS1E, respectively. An asd-mutated E. coli transformed with these vectors could grow without diaminopimelic acid (DAP), indicating that they were stably maintained in such mutants. ClyA-S1E recombinant proteins from these vectors were expressed on the surface of the attenuated S. typhimurium deficient of global virulence gene regulator, ppGpp. However, they did not show the hemolytic activity on the blood agar plate and cytotoxicity against HeLa cells. To examine whether bacteria expressing ClyA-S1E induced the immune response against S1E, S. typhimurium deficient of ppGpp and Asd was transformed with these vectors and orally immunized in mice. In the western blotting against GST-conjugated S1E using the immunized mouse sera, it was shown that the significant band was detected in the mouse serum by the bacteria transformed with pGApLCS1E but not with pBApLCS1E. It indicates that the immune response producing antibody was dependent on the expression level of ClyA-S1E. Therefore, ClyA delivery system can be used for SARS vaccine development.

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“…The hlyF gene, its product HlyF, and its mode of action still need to be characterized. HlyF has hemolytic activity, but its amino acid sequence shows no significant homology to HlyA, the RTX hemolysin of several E. coli pathotypes, or to HlyE, a more recently identified hemolysin distinct from HlyA (134)(135)(136)(137). Besides HlyF, the HlyA hemolysin is associated with plasmids.…”

Section: Hemolysinmentioning

confidence: 99%

Plasmid-Encoded Iron Uptake Systems

Lorenzo

Stork

2014

Microbiol Spectr

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Plasmids confer genetic information that benefits the bacterial cells containing them. In pathogenic bacteria, plasmids often harbor virulence determinants that enhance the pathogenicity of the bacterium. The ability to acquire iron in environments where it is limited, for instance the eukaryotic host, is a critical factor for bacterial growth. To acquire iron, bacteria have evolved specific iron uptake mechanisms. These systems are often chromosomally encoded, while those that are plasmid-encoded are rare. Two main plasmid types, ColV and pJM1, have been shown to harbor determinants that increase virulence by providing the cell with essential iron for growth. It is clear that these two plasmid groups evolved independently from each other since they do not share similarities either in the plasmid backbones or in the iron uptake systems they harbor. The siderophores aerobactin and salmochelin that are found on ColV plasmids fall in the hydroxamate and catechol group, respectively, whereas both functional groups are present in the anguibactin siderophore, the only iron uptake system found on pJM1-type plasmids. Besides siderophore-mediated iron uptake, ColV plasmids carry additional genes involved in iron metabolism. These systems include ABC transporters, hemolysins, and a hemoglobin protease. ColV-and pJM1-like plasmids have been shown to confer virulence to their bacterial host, and this trait can be completely ascribed to their encoded iron uptake systems.

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Detection of a Novel Virulence Gene and a Salmonella Virulence Homologue Among Escherichia coli Isolated from Broiler Chickens

Cited by 51 publications

References 29 publications

Complete DNA Sequence of a ColBM Plasmid from Avian Pathogenic Escherichia coli Suggests that It Evolved from Closely Related ColV Virulence Plasmids

Complete DNA Sequence of a ColBM Plasmid from Avian Pathogenic Escherichia coli Suggests that It Evolved from Closely Related ColV Virulence Plasmids

The Bacterial Surface Expression of SARS Viral Epitope using Salmonella typhi Cytolysin A

Plasmid-Encoded Iron Uptake Systems

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