Cholera Toxin Production by the El Tor Variant of<i>Vibrio cholerae</i>O1 Compared to Prototype El Tor and Classical Biotypes

Ghosh-Banerjee, Jayeeta; Senoh, Mitsutoshi; Takahashi, Takuya; Hamabata, Takashi; Barman, Soumik; Koley, Hemanta; Mukhopadhyay, Asish K.; Ramamurthy, Thandavarayan; Chatterjee, Shruti; Asakura, Masahiro; Yamasaki, Shinji; Nair, G. Balakrish; Takeda, Yoshifumi

doi:10.1128/jcm.00799-10

Cited by 82 publications

(60 citation statements)

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“…Another common ET isolate, N16961, produced more CT than other ET strains, which was expected, as this strain has previously been found to produce more CT than other ET strains and, as observed in this study for 2010EL-1786 (Fig. 1B), at levels that overlapped the amount expressed by AET strains (31). These results confirm results by others that 2010EL-1786 expresses ϳ2-fold more CT than N16961 and ϳ10-fold more than C6706 (a strain closely related to C6709) (17) and that AET strains in general produce more CT and induce secretion of more fluid in rabbit ileal loops (31).…”

Section: Overproduction Of Secreted Toxins By An Aet Isolate From Haitisupporting

confidence: 65%

Phenotypic Analysis Reveals that the 2010 Haiti Cholera Epidemic Is Linked to a Hypervirulent Strain

et al. 2016

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bVibrio cholerae O1 El Tor strains have been responsible for pandemic cholera since 1961. These strains have evolved over time, spreading globally in three separate waves. Wave 3 is caused by altered El Tor (AET) variant strains, which include the strain with the signature ctxB7 allele that was introduced in 2010 into Haiti, where it caused a devastating epidemic. In this study, we used phenotypic analysis to compare an early isolate from the Haiti epidemic to wave 1 El Tor isolates commonly used for research. It is demonstrated that the Haiti isolate has increased production of cholera toxin (CT) and hemolysin, increased motility, and a reduced ability to form biofilms. This strain also outcompetes common wave 1 El Tor isolates for colonization of infant mice, indicating that it has increased virulence. Monitoring of CT production and motility in additional wave 3 isolates revealed that this phenotypic variation likely evolved over time rather than in a single genetic event. Analysis of available whole-genome sequences and phylogenetic analyses suggested that increased virulence arose from positive selection for mutations found in known and putative regulatory genes, including hns and vieA, diguanylate cyclase genes, and genes belonging to the lysR and gntR regulatory families. Overall, the studies presented here revealed that V. cholerae virulence potential can evolve and that the currently prevalent wave 3 AET strains are both phenotypically distinct from and more virulent than many El Tor isolates.

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Section: Overproduction Of Secreted Toxins By An Aet Isolate From Haitisupporting

confidence: 65%

Phenotypic Analysis Reveals that the 2010 Haiti Cholera Epidemic Is Linked to a Hypervirulent Strain

et al. 2016

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“…With the differences in the locations of where these diverse variants are being isolated come the inherent differences in genotypic and phenotypic profiles, as previously described elsewhere (28,29,33,39,44,45). An alarming concern has been the growing number of unpublished reports and one recently published report (16) revealing various amounts of cholera toxin being produced by the different El Tor variants isolated. Our initial clinical patient profiles (Table 1) revealed that the patients all suffered from severe watery diarrhea, a hallmark manifestation of cholera.…”

Section: Vol 49 2011 Characterization Of Clinical El Tor Variant Ismentioning

confidence: 99%

“…These El Tor variants have become a major focus of research, since other El Tor variants also have been identified in Asia and Mozambique (29,34,35,38) and recently have been a focus of attention in Haiti (1,6,7,8,9). Of particular concern are the recently published results indicating that some of the clinically isolated El Tor variants produce different levels of cholera toxin, including some isolates that produce higher levels than classical biotype strains (16). Although evidence has been presented demonstrating that the El Tor biotype has globally displaced the classical biotype (19,42), the emergence of El Tor variants has warranted the use of standard genotypic and phenotypic assays to determine the biotype background of new isolates.…”

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confidence: 99%

Characterization of Vibrio cholerae O1 El Tor Biotype Variant Clinical Isolates from Bangladesh and Haiti, Including a Molecular Genetic Analysis of Virulence Genes

et al. 2011

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Vibrio cholerae serogroup O1, the causative agent of the diarrheal disease cholera, is divided into two biotypes: classical and El Tor. Both biotypes produce the major virulence factors toxin-coregulated pilus (TCP) and cholera toxin (CT). Although possessing genotypic and phenotypic differences, El Tor biotype strains displaying classical biotype traits have been reported and subsequently were dubbed El Tor variants. Of particular interest are reports of El Tor variants that produce various levels of CT, including levels typical of classical biotype strains. Here, we report the characterization of 10 clinical isolates from the International Centre for Diarrhoeal Disease Research, Bangladesh, and a representative strain from the 2010 Haiti cholera outbreak. We observed that all 11 strains produced increased CT (2-to 10-fold) compared to that of wild-type El Tor strains under in vitro inducing conditions, but they possessed various TcpA and ToxT expression profiles. Particularly, El Tor variant MQ1795, which produced the highest level of CT and very high levels of TcpA and ToxT, demonstrated hypervirulence compared to the virulence of El Tor wild-type strains in the infant mouse cholera model. Additional genotypic and phenotypic tests were conducted to characterize the variants, including an assessment of biotype-distinguishing characteristics. Notably, the sequencing of ctxB in some El Tor variants revealed two copies of classical ctxB, one per chromosome, contrary to previous reports that located ctxAB only on the large chromosome of El Tor biotype strains.Vibrio cholerae is a Gram-negative, curved-rod-shaped bacterium that is the causative agent of the watery diarrheal disease cholera. The structure of the cell surface lipopolysaccharide O antigen is used to classify V. cholerae into more than 200 serogroups, of which only two, O1 and O139, possess the potential to cause epidemic or pandemic cholera. The O1 serogroup is further divided into two biotypes, classical and El Tor, which evolved from independent lineages (20, 22), and they display genotypic and phenotypic differences.V. cholerae O1 is distinguished by two of its major virulence factors, cholera toxin (CT) and the toxin-coregulated pilus (TCP). The cholera toxin is encoded by ctxA and ctxB, which are found on the CTX prophage (49), and is responsible for the manifestation of diarrheal disease with severe water and electrolyte loss. The TCP, encoded by the tcp operon in the Vibrio pathogenicity island (VPI), is required for V.

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“…The amount of CT produced was measured as described previously (32,33) during the growth of the representative strains from Zanzibar in AKI medium and compared with prototype El Tor and classical strains. It was found that all the El Tor variant strains from Zanzibar produced significantly larger amounts of CT in vitro than most strains of prototype El Tor (P Ͻ 0.001, MannWhitney U test) (Fig.…”

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confidence: 99%

Molecular Characterization of High-Level-Cholera-Toxin-Producing El Tor Variant Vibrio cholerae Strains in the Zanzibar Archipelago of Tanzania

et al. 2013

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f Analysis of 1,180 diarrheal stool samples in Zanzibar detected 247 Vibrio cholerae O1, Ogawa strains in 2009. Phenotypic traits and PCR-based detection of rstR, rtxC, and tcpA alleles showed that they belonged to the El Tor biotype. Genetic analysis of ctxB of these strains revealed that they were classical type, and production of classical cholera toxin B (CTB) was confirmed by Western blotting. These strains produced more CT than the prototype El Tor and formed a separate cluster by pulsed-field gel electrophoresis (PFGE) analysis.

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Cholera Toxin Production by the El Tor Variant ofVibrio choleraeO1 Compared to Prototype El Tor and Classical Biotypes

Abstract: Vibrio cholerae O1 El Tor variant strains produced much more cholera toxin than did prototype El Tor strains. The amount of cholera toxin produced by El Tor variant strains both in vitro and in vivo was more or less equivalent to that produced by classical strains.

Cited by 82 publications

References 17 publications

Phenotypic Analysis Reveals that the 2010 Haiti Cholera Epidemic Is Linked to a Hypervirulent Strain

Phenotypic Analysis Reveals that the 2010 Haiti Cholera Epidemic Is Linked to a Hypervirulent Strain

Characterization of Vibrio cholerae O1 El Tor Biotype Variant Clinical Isolates from Bangladesh and Haiti, Including a Molecular Genetic Analysis of Virulence Genes

Molecular Characterization of High-Level-Cholera-Toxin-Producing El Tor Variant Vibrio cholerae Strains in the Zanzibar Archipelago of Tanzania

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