Distribution Of The Ace, Zot, And Ctxa Toxin Genes In Clinical And Environmental Vibrio Cholerae [X]

Colombo, Mauro; Mastrandrea, Scilla; Santona, Antonella; Andrade, Anamaria Pinto de; Uzzau, Sergio; Rubino, Salvatore; Cappuccinelli, Piero

doi:10.1093/infdis/170.3.750

Cited by 33 publications

(26 citation statements)

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“…These ¢nd- 3 3 3 3 3 3 3 1 1 3 Total 297 58 18 ings are consistent with other studies which reported incomplete CTX elements [2,18,20]. Furthermore, our data suggest that 30% of the V. cholerae O1 strains in Brazil do not have a complete VPI.…”

Section: Discussionsupporting

confidence: 91%

Prevalence of virulence-associated genes in clinical and environmental Vibrio cholerae strains isolated in Brazil between 1991 and 1999

Brazil¹

2002

FEMS Microbiology Letters

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Genes located on the CTX element and the Vibrio cholerae pathogenicity island (VPI) were investigated in 297 clinical V. cholerae O1 and 76 environmental O1 and non-O1 isolates from Brazil between 1991 and 1999. RAPD analysis suggested that serogroup O1 strains regardless of clinical or environmental source were clonal while non-O1 strains showed greater diversity. PCR analysis showed that 71% of O1 clinical isolates had a complete set of CTX element target genes (ctxA, ctxB, zot and ace) and 68% a complete set of the VPI genes studied (orf1, aldA, tagA, tcpA, toxT and int genes). The results also showed that 72.4% of environmental O1 isolates possessed ctxA, ctxB, zot and ace genes while environmental non-O1 strains rarely possessed virulence genes. Our data are consistent with the hypothesis that the CTX element and the VPI can have a mosaic structure in some V. cholerae strains, genotype diversity is due to the circulation of virulence genes which are more commonly found in O1 strains in Brazil. This study also shows that the aquatic environment is a potential source for virulence genes and toxigenic V. cholerae during epidemic periods. ß 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.Keywords : Vibrio cholerae; CTX; Vibrio cholerae pathogenicity island; Random ampli¢ed polymorphic DNA IntroductionVibrio cholerae as a species includes both pathogenic and non-pathogenic strains that vary in their virulence gene content [1,2]. Pathogenic and epidemic strains of V. cholerae possess two essential genetic elements which are absent in non-pathogenic strains, the CTX element [3] and the V. cholerae pathogenicity island (VPI) [4]. The CTX element encodes cholera toxin (CT) which is primarily responsible for the severe secretory diarrhea. The CT and adjacent genes are part of a lysogenic ¢lamentous bacteriophage [5]. The VPI, which also appears to be derived from a bacteriophage, is a 41.2-kb pathogenicity island potentially encoding 29 proteins [4,6,7]. The type IV pilus toxin-coregulated pilus (TCP) is encoded by the VPI and functions both as an essential colonization factor and as a receptor for the CTXx [5,8].The current seventh pandemic of cholera began in 1961 on the island of Sulawesi and soon spread worldwide [9]. In January 1991 cholera appeared in many Latin American countries after a period of about 100 years of absence [10,11]. In Brazil, 167 718 clinical cholera cases were documented and 2009 deaths recorded between 1991 and 1999. The disease began and occurred mainly in the northeastern region of the country and accounted for 92.1% of the country's total cases [12^14]. However, due to poor sanitation conditions cholera epidemics still occur in some Brazilian States, such as Pernambuco and Alagoas [13].It has been suggested that non-toxigenic environmental strains of V. cholerae can emerge into epidemic strains if they acquire the appropriate set of virulence genes [4,7,15]. However, the prevalence of virulence genes in environmental s...

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Section: Discussionsupporting

confidence: 91%

Prevalence of virulence-associated genes in clinical and environmental Vibrio cholerae strains isolated in Brazil between 1991 and 1999

Brazil¹

2002

FEMS Microbiology Letters

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“…DISCUSSION V. cholerae, the human intestinal pathogen responsible for the diarrheal disease cholera, elaborates a large number of extracellular proteins, including several virulence factors. A number of epidemiological studies (22,23) have shown a concurrent occurrence of the CT genes (ctx A and ctx B) and the genes for two other virulence factors elaborated by V. cholerae, Zot (1) and accessory cholera toxin (Ace) (4). This cluster of genes has been recently described as part of a filamentous phage (CTX⌽) that lives in symbiosis with its bacterial host.…”

Section: Construction Of Zot Deletionmentioning

confidence: 99%

Zonula Occludens Toxin Structure-Function Analysis

Pierro

Lu²,

Uzzau

et al. 2001

Journal of Biological Chemistry

178

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Zonula occludens toxin (Zot) is an enterotoxin elaborated by Vibrio cholerae that increases intestinal permeability by interacting with a mammalian cell receptor with subsequent activation of intracellular signaling leading to the disassembly of the intercellular tight junctions. Zot localizes in the bacterial outer membrane of V. cholerae with subsequent cleavage and secretion of a carboxyl-terminal fragment in the host intestinal milieu. To identify the Zot domain(s) directly involved in the protein permeating effect, several zot gene deletion mutants were constructed and tested for their biological activity in the Ussing chamber assay and their ability to bind to the target receptor on intestinal epithelial cell cultures. The Zot biologically active domain was localized toward the carboxyl terminus of the protein and coincided with the predicted cleavage product generated by V. cholerae. This domain shared a putative receptor-binding motif with zonulin, the Zot mammalian analogue involved in tight junction modulation. Amino acid comparison between the Zot active fragment and zonulin, combined with site-directed mutagenesis experiments, confirmed the presence of an octapeptide receptor-binding domain toward the amino terminus of the processed Zot.Vibrio cholerae produces a variety of extracellular products including zonula occludens toxin (Zot) 1 (1). The zot gene, along with other genes encoding virulence factors such as ctxA, ctxB (2, 3), and ace (4), is part of the chromosomally integrated genome of a filamentous phage designated CTX⌽ (5-10). The zot product seems to be involved in the CTX⌽ morphogenesis because Zot mutagenesis studies demonstrated the inability of CTX elements to be self-transmissible under appropriate conditions (5). The high concurrence among V. cholerae strains of the zot gene and the ctx genes (11, 12) also suggests a possible synergistic role of Zot in the causation of acute dehydrating diarrhea typical of cholera. The recently completed genomic sequence of V. choleare El Tor N16961 revealed that the CTX⌽ filamentous phage is integrated in one of the two circular chromosomes of the bacterium (13).Beside its role in phage morphogenesis, Zot also increases the permeability of the small intestine by affecting the structure of the intercellular tight junctions (tj) (1). This effect was initially described on rabbit ileal tissues mounted in Ussing chambers by using filtered supernatants from V. cholerae O1 strains, suggesting that Zot is secreted (1, 14). Zot also possesses a cell specificity related to the toxin interaction with a specific receptor whose surface expression differs on various cells (15-17). Zot induces modifications of cytoskeletal organization that lead to the opening of tj secondary to the transmembrane phospholipase C and subsequent protein kinase C␣-dependent polymerization of actin filaments strategically localized to regulate the paracellular pathway (15). Furthermore, in vivo experiments suggested that the effect of Zot on tj might lead to intestinal secretion after...

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“…Primer pairs were used to detect the following: a 301-bp fragment of ctxA [21], a 471-bp fragment of El Tor variant of tcpA, a 671-bp fragment of classical variant of tcpA [22], a 990-bp fragment of toxR [23], a 243-bp fragment of zot and a 284-bp fragment of ace [24].…”

Section: Polymerase Chain Reaction Assaymentioning

confidence: 99%

Response of wild-type mutants of Vibrio cholerae O1 possessing different combinations of virulence genes in the ligated rabbit ileal loop and in Ussing chambers: evidence for the presence of additional secretogen

Koley¹,

Mitra²,

Basu³

et al. 1999

Journal of Medical Microbiology

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Five wild-type mutant strains of Vibrio cholerae serogroup 01 that lacked the CTX virulence cassette, or contained a natural deletion of a virulence gene within the CTX virulence cassette, or possessed an additional virulence gene, along with a prototype toxigenic strain representing the El Tor classical biotypes were examined by in-vivo and in-vitro methods to determine their enterotoxic potential. The ability of whole cells and culture supernates of the strains to cause fluid accumulation in the rabbit ileal loop model revealed a pattern consistent with the presence of the various virulence gene(s), with those possessing the intact CTX virulence cassette being the most secretogenic. Culture supernates of strains without the CTX virulence cassette or the strain with an incomplete cassette were also able to evoke mild to moderate fluid accumulation in the rabbit ileal loop. Of the various media used, AKI and brain heart infusion broth appeared to support the production of a hitherto unknown secretogenic factor, because culture supernates of the non-toxigenic K cholerae 01 strains showed higher fluid accumulation ratios when grown in these media than in the others. To confirm that the fluid accumulation elicited by these strains in the ileal loop was due to enterotoxin activity, the effect of supernate of the strains was examined in rabbit small intestine mounted on Ussing chambers. Increases in short circuit current and tissue conductance, as compared with the medium control, were observed even with the strains that did not possess the CTX virulence cassette, confirming their ability to disrupt the function of intestinal tissue. From these studies, it was concluded that strains of K cholerae 01 devoid of the CTX virulence cassette were still able to elicit a secretory response in the ileal loop and displayed enterotoxic activity in an in-vitro experimental model.

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Distribution Of The Ace, Zot, And Ctxa Toxin Genes In Clinical And Environmental Vibrio Cholerae [X]

Cited by 33 publications

References 0 publications

Prevalence of virulence-associated genes in clinical and environmental Vibrio cholerae strains isolated in Brazil between 1991 and 1999

Prevalence of virulence-associated genes in clinical and environmental Vibrio cholerae strains isolated in Brazil between 1991 and 1999

Zonula Occludens Toxin Structure-Function Analysis

Response of wild-type mutants of Vibrio cholerae O1 possessing different combinations of virulence genes in the ligated rabbit ileal loop and in Ussing chambers: evidence for the presence of additional secretogen

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