Cholera toxin (CTX) genetic element in Vibrio cholerae O139

Bhadra, Rupak K.; Roychoudhury, Susanta; Banerjee, Rajat; Kar, Sudeshna; Majumdar, Ruma; Sengupta, Sanghamitra; Chatterjee, S.; Khetawat, Gopal; Das, Jyotirmoy

doi:10.1099/13500872-141-8-1977

Cited by 38 publications

(47 citation statements)

References 21 publications

(46 reference statements)

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“…Evolution of the seventh pandemic El Tor strains that replaced the sixth pandemic classical strains may have happened due to the better flexibility of the genomes of the former. Several lines of evidence also indicate that the organization of the ctx locus and the genome of the classical strain were highly stable compared to the El Tor biotype (Bhadra et al, 1995;Davis et al, 1999;Mekalanos, 1983;Nair, 1996;Nandi et al, 1997). This is further supported by the epidemiological data that establish El Tor as the longest-ruling strain in the history of cholera (Faruque et al, 1998;Kaper et al, 1995).…”

Section: Mapping Of the Locations Of Ctx Prophage In The El Tor Genomessupporting

confidence: 55%

“…Standard molecular methods were followed throughout the study (Sambrook et al, 1989). For hybridization experiments, the ctxA gene was obtained as described previously (Bhadra et al, 1995). The position of the ctxA gene probe is shown in Fig.…”

Section: Methodsmentioning

confidence: 99%

“…About 50 ng of DNA was labelled with [a-32 P]dCTP (Amersham Biosciences) by the random-priming method using the NEBlot kit (New England Biolabs). For Southern blot hybridization, bacterial genomic DNA was digested with restriction endonucleases, separated by electrophoresis, transferred to Hybond-N + membranes (Amersham Biosciences) and hybridized with a labelled DNA probe at 60˚C in a hybridization oven as described previously (Bhadra et al, 1995;Khetawat et al, 1999). The membranes were washed under stringent conditions, dried and exposed to Kodak X-OMAT AR5 films.…”

Section: Methodsmentioning

confidence: 99%

“…The enzyme-digested V. cholerae genomic DNA was hybridized with the ctxA or RS probe (Fig. 4) and the blots were analysed extensively as described previously (Bhadra et al, 1995;Khetawat et al, 1999). The hybridization results are summarized in Table 2.…”

Section: Mapping Of the Locations Of Ctx Prophage In The El Tor Genomesmentioning

confidence: 99%

“…However, in late 1992, CT-producing V. cholerae O139 Bengal emerged as the first non-O1 strain to cause an explosive cholera epidemic in the Indian subcontinent by replacing the seventh pandemic strains of the V. cholerae O1 El Tor biotype (Albert et al, 1993;Ramamurthy et al, 1993). V. cholerae O139 strains isolated from different parts of India and Bangladesh during the epidemic were found to be of clonal origin, and several lines of evidence have suggested that strain O139 arose from an El Tor biotype (Bhadra et al, 1994(Bhadra et al, , 1995Bik et al, 1995;Waldor & Mekalanos, 1994). Interestingly, within about one year, O1 El Tor strains reappeared in the same area as the dominant serogroup, replacing the O139 Bengal clone (Mukhopadhyay et al, 1995(Mukhopadhyay et al, , 1996a; molecular characterization of El Tor strains isolated prior to and after the O139 epidemic revealed that they were genotypically different from each other (Sharma et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

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Genesis of variants of Vibrio cholerae O1 biotype El Tor: role of the CTX array and its position in the genome

et al. 2003

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The gene encoding cholera toxin, the principal virulence factor of Vibrio cholerae, is encoded by a filamentous, lysogenic bacteriophage known as CTXf. The genome of V. cholerae, the host for CTXf, consists of two chromosomes, one large and one small. Here, it is shown that localization and array of CTX prophage DNA in either the large or small chromosome of V. cholerae is likely to be one of the reasons for the emergence of O1 biotype El Tor variants isolated just before and after the V. cholerae O139 cholera outbreak in 1992. Analyses of the organization of the CTX region of the genome of pre-O139 El Tor strains revealed that these strains carry two distinct CTX prophages integrated in the small chromosome in tandem: CTX ET , the prophage having a conserved NotI site in its repeat sequence segment which seems to be specific for the El Tor strains so far examined, followed by CTX calc -like genome, the prophage found in recent O139 clinical isolates from Calcutta. In sharp contrast, in post-O139 El Tor strains only one copy of the CTX ET prophage was found to be integrated in the large chromosome. To the authors' knowledge, the presence of CTX prophage in the small chromosome of O1 El Tor strains has not been reported previously. It is also shown that the difference in the CTX copy number and the position of the bacteriophage on the genomes of pre-and post-O139 El Tor strains have an effect on cholera toxin production. While a pre-O139 strain produced maximum cholera toxin in yeast extract/peptone medium at 30˚C, a post-O139 El Tor strain showed maximal yield at 37˚C, indicating differential regulation of cholera toxin between the strains. It appears from this study that the variation in the integration site of the CTX prophage, its copy number and the presence of diverse phage genomes in V. cholerae O1 biotype El Tor may be strategically important for generating variants with subtle phenotypic modulations of virulence factor production in this longest-ruling seventh pandemic strain.

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Section: Mapping Of the Locations Of Ctx Prophage In The El Tor Genomessupporting

confidence: 55%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Mapping Of the Locations Of Ctx Prophage In The El Tor Genomesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Genesis of variants of Vibrio cholerae O1 biotype El Tor: role of the CTX array and its position in the genome

et al. 2003

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Heterogeneity in the organization of the CTX genetic element in strains ofVibrio choleraeO139 Bengal isolated from Calcutta, India and Dhaka, Bangladesh and its possible link to the dissimilar incidence of O139 cholera in the two locales

Basu

Mukhopadhyay

Sharma

et al. 1998

Microbial Pathogenesis

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Cholera Outbreaks in India

Ramamurthy

Sharma²

2014

Cholera Outbreaks

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Cholera is a global health problem as several thousands of cases and deaths occur each year. The unique epidemiologic attribute of the disease is its propensity to occur as outbreaks that may flare-up into epidemics, if not controlled. The causative bacterial pathogen Vibrio cholerae prevails in the environment and infects humans whenever there is a breakdown in the public health component. The Indian subcontinent is vulnerable to this disease due its vast coastlines with areas of poor sanitation, unsafe drinking water, and overcrowding. Recently, it was shown that climatic conditions also play a major role in the persistence and spread of cholera. Constant change in the biotypes and serotypes of V. cholerae are also important aspects that changes virulence and survival of the pathogen. Such continuous changes increase the infection ability of the pathogen affecting the susceptible population including the children. The short-term carrier status of V. cholerae has been studied well at community level and this facet significantly contributes to the recurrence of cholera. Several molecular tools recognized altering clonality of V. cholerae in relation with the advent of a serogroup or serotype. Rapid identification systems were formulated for the timely detection of the pathogen so as to identify and control the outbreak and institute proper treatment of the patients. The antimicrobials used in the past are no longer useful in the treatment of cholera as V. cholerae has acquired several mechanisms for multiple antimicrobial resistance. This upsurge in antimicrobial resistance directly influences the management of the disease. This chapter provides an overview of cholera prevalence in India, possible sources of infection, and molecular epidemiology along with antimicrobial resistance of V. cholerae.

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Cholera toxin (CTX) genetic element in Vibrio cholerae O139

Cited by 38 publications

References 21 publications

Genesis of variants of Vibrio cholerae O1 biotype El Tor: role of the CTX array and its position in the genome

Genesis of variants of Vibrio cholerae O1 biotype El Tor: role of the CTX array and its position in the genome

Heterogeneity in the organization of the CTX genetic element in strains ofVibrio choleraeO139 Bengal isolated from Calcutta, India and Dhaka, Bangladesh and its possible link to the dissimilar incidence of O139 cholera in the two locales

Cholera Outbreaks in India

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