scholarly journals Vibrio cholerae O1 clinical strains isolated in 1992 in Kolkata with progenitor traits of the 2004 Mozambique variant

2009 ◽  
Vol 58 (2) ◽  
pp. 239-247 ◽  
Author(s):  
Souvik Chatterjee ◽  
Tapas Patra ◽  
Kausik Ghosh ◽  
Amit Raychoudhuri ◽  
Gururaja P. Pazhani ◽  
...  
Keyword(s):  
Retrospective Analysis ◽  
Vibrio Cholerae ◽  
Polymyxin B ◽  
Small Chromosome ◽  
Phenotypic Traits ◽  
Clinical Strains ◽  
Vibrio Cholerae O1 ◽  
Ctx Prophage ◽  
El Tor ◽  
Clinical Cases

Retrospective analysis led to the detection of two Vibrio cholerae variant O1 strains (VC51 and VC53), which were isolated in 1992 in Kolkata from clinical cases, with identical traits to 2004 Mozambique variant O1 strains. The Mozambique O1 strains that caused a huge outbreak in 2004 have been shown to have phenotypic traits of both classical and El Tor biotypes, and thereby have been reported as variant. Our study demonstrated that two O1 strains isolated in Kolkata during 1992 were of the El Tor background as evidenced by polymyxin B (50 U ml−1) resistance, positivity in Voges–Proskauer reactions and sensitivity to biotype-specific vibrio phages. With the features of classical CTX prophage, localization in the small chromosome, and an absence of RS1 and pTLC, both Mozambique and Kolkata strains appeared to be identical. Furthermore, two Kolkata strains exhibited an identical ribotype to that of the Mozambique variant, displaying ribotype pattern RI that had been assigned to Kolkata V. cholerae O1 strains isolated on or before 1992. NotI pulsotype analysis indicated that these 1992 Kolkata strains along with the Mozambique variant O1 belonged to very closely related clones. Considering the chronological events, and the typical identity at the phenotypic and the genotypic level between the two O1 strains isolated during 1992 from Kolkata and during 2004 from Mozambique, we propose that some of the 1992 Kolkata O1 strains might have acted as progenitors for Mozambique variant O1 strains.

Classical RS1 and environmental RS1 elements in Vibrio cholerae O1 El Tor strains harbouring a tandem repeat of CTX prophage: revisiting Mozambique in 2005

2010 ◽  
Vol 59 (3) ◽  
pp. 302-308 ◽  
Author(s):  
Seon Young Choi ◽  
Je Hee Lee ◽  
Eun Jin Kim ◽  
Hye Ri Lee ◽  
Yoon-Seong Jeon ◽  
...  
Keyword(s):  
Cholera Toxin ◽  
Vibrio Cholerae ◽  
Tandem Repeat ◽  
Small Chromosome ◽  
Classical Type ◽  
Large Chromosome ◽  
New Type ◽  
Vibrio Cholerae O1 ◽  
Ctx Prophage ◽  
El Tor

Currently, Vibrio cholerae O1 serogroup biotype El Tor strains producing classical type cholera toxin (altered strains or El Tor variants) are prevalent in Asia and in Mozambique. Mozambican strains collected in 2004 contained a tandem repeat of CTX prophage on the small chromosome and each CTX prophage harboured the classical rstR and classical ctxB. We found that the majority of the strains collected in 2005 in Mozambique contained extra elements on the large chromosome in addition to the tandem repeat of CTX prophage on the small chromosome. New type RS1 elements RS1cla and RS1env, and a CTXenv with rstR env and the classical ctxB were identified on the large chromosome of the Mozambican isolates collected in 2005.

scholarly journals Multilocus sequence typing (MLST) analysis of Vibrio cholerae O1 El Tor isolates from Mozambique that harbour the classical CTX prophage

2006 ◽  
Vol 55 (2) ◽  
pp. 165-170 ◽  
Author(s):  
Je Hee Lee ◽  
Kyung Ho Han ◽  
Seon Young Choi ◽  
Marcelino E. S. Lucas ◽  
C. Mondlane ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Tandem Repeat ◽  
Multilocus Sequence Typing ◽  
Sequence Type ◽  
Genetic Loci ◽  
Mlst Analysis ◽  
Vibrio Cholerae O1 ◽  
Ctx Prophage ◽  
El Tor

Vibrio cholerae O1 isolates belonging to the Ogawa serotype, El Tor biotype, harbouring the classical CTX prophage were first isolated in Mozambique in 2004. Multilocus sequence typing (MLST) analysis using nine genetic loci showed that the Mozambique isolates have the same sequence type (ST) as O1 El Tor N16961, a representative of the current seventh cholera pandemic. Analysis of the CTX prophage in the Mozambique isolates indicated that there is one type of rstR in these isolates: the classical CTX prophage. It was also found that the ctxB-rstR-rstA-rstB-phs-cep fragment was PCR-amplified from these isolates, which indicates the presence of a tandem repeat of the classical CTX prophage in the genome of the Mozambique isolates. The possible origin of these isolates and the presence of the tandem repeat of the classical prophage in them implicate the presence of the classical CTX phage.

scholarly journals Genetic Diversity of Toxigenic and Nontoxigenic Vibrio cholerae Serogroups O1 and O139 Revealed by Array-Based Comparative Genomic Hybridization

2007 ◽  
Vol 189 (13) ◽  
pp. 4837-4849 ◽  
Author(s):  
Bo Pang ◽  
Meiying Yan ◽  
Zhigang Cui ◽  
Xiaofen Ye ◽  
Baowei Diao ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Clonal Selection ◽  
Gene Clusters ◽  
Small Chromosome ◽  
Genomic Diversity ◽  
Comparative Genomic ◽  
Pathogenic Potential ◽  
Genomic Microarray ◽  
Ctx Prophage ◽  
El Tor

ABSTRACT Toxigenic serogroups O1 and O139 of Vibrio cholerae may cause cholera epidemics or pandemics. Nontoxigenic strains within these serogroups also exist in the environment, and also some may cause sporadic cases of disease. Herein, we investigate the genomic diversity among toxigenic and nontoxigenic O1 and O139 strains by comparative genomic microarray hybridization with the genome of El Tor strain N16961 as a base. Conservation of the toxigenic O1 El Tor and O139 strains is found as previously reported, whereas accumulation of genome changes was documented in toxigenic El Tor strains isolated within the 40 years of the seventh pandemic. High phylogenetic diversity in nontoxigenic O1 and O139 strains is observed, and most of the genes absent from nontoxigenic strains are clustered together in the N16961 genome. By comparing these toxigenic and nontoxigenic strains, we observed that the small chromosome of V. cholerae is quite conservative and stable, outside of the superintegron region. In contrast to the general stability of the genome, the superintegron demonstrates pronounced divergence among toxigenic and nontoxigenic strains. Additionally, sequence variation in virulence-related genes is found in nontoxigenic El Tor strains, and we speculate that these intermediate strains may have pathogenic potential should they acquire CTX prophage alleles and other gene clusters. This genome-wide comparison of toxigenic and nontoxigenic V. cholerae strains may promote understanding of clonal differentiation of V. cholerae and contribute to an understanding of the origins and clonal selection of epidemic strains.

scholarly journals Multilocus genetic analysis reveals that the Australian strains of Vibrio cholerae O1 are similar to the pre-seventh pandemic strains of the El Tor biotype

2009 ◽  
Vol 58 (1) ◽  
pp. 105-111 ◽  
Author(s):  
Ashrafus Safa ◽  
Nurul A. Bhuiyan ◽  
Denise Murphy ◽  
John Bates ◽  
Suraia Nusrin ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Genetic Screening ◽  
Phenotypic Traits ◽  
Pfge Analysis ◽  
Genotype 2 ◽  
Environmental Reservoir ◽  
Vibrio Cholerae O1 ◽  
Pandemic Strains ◽  
Genomic Regions ◽  
El Tor

Episodes of cholera stemming from indigenous Vibrio cholerae strains in Australia are mainly associated with environmental sources. In the present study, 10 V. cholerae O1 strains of Australian origin were characterized. All of the strains were serogroup O1 and their conventional phenotypic traits categorized them as belonging to the El Tor biotype. Genetic screening of 12 genomic regions that are associated with virulence in V. cholerae showed variable results. Analysis of the ctxAB gene showed that the Australian environmental reservoir contains both toxigenic and non-toxigenic V. cholerae strains. DNA sequencing revealed that all of the toxigenic V. cholerae strains examined were of ctxB genotype 2. Whole genome PFGE analysis revealed that the environmental toxigenic V. cholerae O1 strains were more diverse than the non-toxigenic environmental O1 strains, and the absence of genes that make up the Vibrio seventh pandemic island-I and -II in all of the strains indicates their pre-seventh pandemic ancestry.

scholarly journals Genetic organization of pre-CTX and CTX prophages in the genome of an environmental Vibrio cholerae non-O1, non-O139 strain

Microbiology ◽  
2006 ◽  
Vol 152 (12) ◽  
pp. 3633-3641 ◽  
Author(s):  
Diganta Maiti ◽  
Bhabatosh Das ◽  
Arjun Saha ◽  
Ranjan K. Nandy ◽  
G. Balakrish Nair ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Genetic Locus ◽  
Single Copy ◽  
Small Chromosome ◽  
Large Chromosome ◽  
Critical Determinant ◽  
Multiple Copies ◽  
New Type ◽  
Ctx Prophage ◽  
El Tor

The cholera toxin (CT) is a critical determinant of the virulence of epidemic Vibrio cholerae strains. The ctxAB operon encoding CT is part of the genome of a filamentous bacteriophage CTXΦ, which may integrate as a single copy or as multiple copies in the genome of V. cholerae. The CTXΦ genome is composed of RS2 (2.4 kb) and core (4.5 kb) regions. In the present study extensive genetic mapping analyses indicated that two copies of tandemly arrayed CTX prophages are integrated in the small chromosome of an environmental V. cholerae strain, VCE232, belonging to serogroup O4. Further mapping revealed that the integration of prophages has occurred in the same genetic locus of the small chromosome of VCE232 as that of V. cholerae O1 biotype El Tor strains. Interestingly, a new type of RS2-like element 3.5 kb in size was found in the CTX prophage genome in the small chromosome of VCE232. Cloning followed by sequencing of the new RS2-like element of VCE232 revealed the presence of three ORFs, which probably encode highly divergent types of phage regulatory proteins. Furthermore, the strain VCE232 also harbours two copies of a tandemly arranged CTX prophage devoid of the ctxAB genes, called pre-CTX prophage, in its large chromosome. The presence of multiple copies of diverse CTX prophages in both the chromosomes of VCE232 suggests that toxigenic environmental V. cholerae non-O1, non-O139 strains could play a role in the emergence of new epidemic clones.

scholarly journals Molecular evidence favouring step-wise evolution of Mozambique Vibrio cholerae O1 El Tor hybrid strain

Microbiology ◽  
2010 ◽  
Vol 156 (1) ◽  
pp. 99-107 ◽  
Author(s):  
Kalpataru Halder ◽  
Bhabatosh Das ◽  
G. Balakrish Nair ◽  
Rupak K. Bhadra
Keyword(s):  
Vibrio Cholerae ◽  
Repeat Sequence ◽  
Molecular Evidence ◽  
Sequence Analyses ◽  
Hybrid Strain ◽  
Repeat Sequences ◽  
Multiple Copies ◽  
Vibrio Cholerae O1 ◽  
Ctx Prophage ◽  
El Tor

The ctxAB operon, encoding cholera toxin (CT) in Vibrio cholerae, is carried by the genome of a filamentous phage, CTXΦ. Usually, specific CTXΦ infect each of the two important biotypes, classical and El Tor, of epidemic V. cholerae strains belonging to serogroup O1, and are called CTXclassΦ and CTXETΦ, respectively. However, an unusual hybrid El Tor strain carrying CTXclassΦ caused the cholera epidemic in Mozambique in 2004. To understand the evolution of that strain, we have further analysed some representative hybrid El Tor strains isolated in Kolkata, India, in 1992, and the results indicate that both the Mozambique and the Indian strains are infected with a unique CTXclassΦ having only four copies of the tandem heptamer repeat sequence 5′-TTTTGAT-3′ present in the ctxAB promoter (P ctxAB ) region, like in CTXETΦ. Usually, the P ctxAB of the classical biotype contains seven to eight copies of such sequences. However, sequence analyses of the P ctxAB regions of several classical strains indicated that the copy number of heptamer repeat sequences might vary from four to eight copies, which was previously unknown. Since the hybrid strains analysed in this study carry four copies of the heptamer sequences, it may thus serve as a marker to trace the strain in future. Interestingly, while the Mozambique strain is devoid of an El Tor-specific free RS1 element or pre-CTX prophage, the Indian hybrid strains carry such elements. The free RS1 has been mapped, cloned and sequenced. As in pre-CTX and CTX prophages, multiple copies of free RS1 elements were found to be integrated in tandem in the large chromosomal dif site. Since Indian hybrid El Tor strains carry either free RS1 or pre-CTX prophage in their large chromosomes, it is possible that the Mozambique hybrid El Tor strain has evolved from these progenitor strains by step-wise deletion of CTX genetic elements from their large chromosomes.

scholarly journals A Point Mutation in carR Is Involved in the Emergence of Polymyxin B-Sensitive Vibrio cholerae O1 El Tor Biotype by Influencing Gene Transcription

2020 ◽  
Vol 88 (5) ◽  
Author(s):  
Prosenjit Samanta ◽  
Rahul Shubhra Mandal ◽  
Rudra Narayan Saha ◽  
Sreeja Shaw ◽  
Priyanka Ghosh ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Lipid A ◽  
Polymyxin B ◽  
Sensitive Strain ◽  
Two Component System ◽  
Content Type ◽  
Vibrio Cholerae O1 ◽  
Binding Cleft ◽  
Culturing Conditions ◽  
El Tor

ABSTRACT Antimicrobial peptides play an important role in host defense against Vibrio cholerae. Generally, the V. cholerae O1 classical biotype is polymyxin B (PB) sensitive and El Tor is relatively resistant. Detection of classical biotype traits like the production of classical cholera toxin and PB sensitivity in El Tor strains has been reported in recent years, including in the devastating Yemen cholera outbreak during 2016-2018. To investigate the factor(s) responsible for the shift in the trend of sensitivity to PB, we studied the two-component system encoded by carRS, regulating the lipid A modification of El Tor vibrios, and found that only carR contains a single nucleotide polymorphism (SNP) in recently emerged PB-sensitive strains. We designated the two alleles present in PB-resistant and -sensitive strains carRr and carRs alleles, respectively, and replaced the carRs allele of a sensitive strain with the carRr allele, using an allelic-exchange approach. The sensitive strain then became resistant. The PB-resistant strain N16961 was made susceptible to PB in a similar fashion. Our in silico CarR protein models suggested that the D89N substitution in the more stable CarRs protein brings the two structural domains of CarR closer, constricting the DNA binding cleft. This probably reduces the expression of the carR-regulated almEFG operon, inducing PB susceptibility. Expression of almEFG in PB-sensitive strains was found to be downregulated under natural culturing conditions. In addition, the expression of carR and almEG decreased in all strains with increased concentrations of extracellular Ca2+ but increased with a rise in pH. The downregulation of almEFG in CarRs strains confirmed that the G265A mutation is responsible for the emergence of PB-sensitive El Tor strains.

scholarly journals Genomic analysis of the Mozambique strain of Vibrio cholerae O1 reveals the origin of El Tor strains carrying classical CTX prophage

2007 ◽  
Vol 104 (12) ◽  
pp. 5151-5156 ◽  
Author(s):  
S. M. Faruque ◽  
V. C. Tam ◽  
N. Chowdhury ◽  
P. Diraphat ◽  
M. Dziejman ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Genomic Analysis ◽  
Vibrio Cholerae O1 ◽  
Ctx Prophage ◽  
El Tor
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