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Author: Yvonne Ann O'Shea Publisher: ISBN: Category : Vibrio cholerae Languages : en Pages : 166
Book Description
Vibrio cholerae is a Gram negative, curved, rod shaped bacterium. V. cholerae is the etiological agent of the diarrheal disease cholera. Of the 200 O antigen serogroups, only 01 and 0139 are known to cause epidemic and pandemic cholera. The 01 serogroup strains are divided into two biotypes classical and E1 Tor. Investigators have long sought to understand the evolution of 7th pandemic El Tor and 0139 strains. Examination of the evolutionary relationships and multilocus virulence gene profiles of V. cholerae isolates indicated that consecutive pandemic strains arose from a common 01 serogroup progenitor through the successive acquisition of new virulence regions. One such region is the Vibrio pathogenicity island (VPI) encoding the toxin co-regulated pilus (TCP) an essential host colonisation factor. The mechanism of transfer of the VPI is unclear, however in this thesis it was shown that the VPI could be transferred between V. cholerae 01 serogroup strains, via a generalised transducing phage. Previously, it was shown that certain chromosomal regions are unique to V. cholerae biotype El Tor strains, which may have led to the success of the 7th pandemic strains. For example the 7.5 kb Vibrio seventh pandemic island II (VSP-II), is one such region. In this thesis, it was found that the 7.5 kb genomic island (GI) is part of a novel 26.9 kb GI and that it shows homology to a 43.4 kb GI in V. vulnificus strain YJ016. It has been suggested that V. cholerae biotype El Tor strains persist longer in aquatic ecosystems. In this thesis, I examined the role of the stringent starvation protein A (ssaA) in stress survival. I investigated growth of a V. cholerae sspAB nutant under a range of physiological stress conditions and show that mutaions in these genes did not effect survival. The evolutionary success of V. cholerae as an endemic and pandemic pathogen may be more related to its improved interaction with the human host that to its improved fitness within environmental reservoirs.
Author: Yvonne Ann O'Shea Publisher: ISBN: Category : Vibrio cholerae Languages : en Pages : 166
Book Description
Vibrio cholerae is a Gram negative, curved, rod shaped bacterium. V. cholerae is the etiological agent of the diarrheal disease cholera. Of the 200 O antigen serogroups, only 01 and 0139 are known to cause epidemic and pandemic cholera. The 01 serogroup strains are divided into two biotypes classical and E1 Tor. Investigators have long sought to understand the evolution of 7th pandemic El Tor and 0139 strains. Examination of the evolutionary relationships and multilocus virulence gene profiles of V. cholerae isolates indicated that consecutive pandemic strains arose from a common 01 serogroup progenitor through the successive acquisition of new virulence regions. One such region is the Vibrio pathogenicity island (VPI) encoding the toxin co-regulated pilus (TCP) an essential host colonisation factor. The mechanism of transfer of the VPI is unclear, however in this thesis it was shown that the VPI could be transferred between V. cholerae 01 serogroup strains, via a generalised transducing phage. Previously, it was shown that certain chromosomal regions are unique to V. cholerae biotype El Tor strains, which may have led to the success of the 7th pandemic strains. For example the 7.5 kb Vibrio seventh pandemic island II (VSP-II), is one such region. In this thesis, it was found that the 7.5 kb genomic island (GI) is part of a novel 26.9 kb GI and that it shows homology to a 43.4 kb GI in V. vulnificus strain YJ016. It has been suggested that V. cholerae biotype El Tor strains persist longer in aquatic ecosystems. In this thesis, I examined the role of the stringent starvation protein A (ssaA) in stress survival. I investigated growth of a V. cholerae sspAB nutant under a range of physiological stress conditions and show that mutaions in these genes did not effect survival. The evolutionary success of V. cholerae as an endemic and pandemic pathogen may be more related to its improved interaction with the human host that to its improved fitness within environmental reservoirs.
Author: Aaron Ross Conrado Publisher: ISBN: Category : Languages : en Pages : 198
Book Description
Horizontal gene transfer amongst bacteria plays a critical role in the evolution, emergence, and virulence of both currently recognized and novel pathogens. Vibrio cholerae exemplifies this process, as benign environmental isolates emerge as pandemic pathogens through the acquisition and incorporation of genetic elements encoding virulence factors into their progenitor genomes. In V. cholerae, these genes are localized to distinct areas of the chromosome, known as horizontally acquired islands (HAIs), which are characterized by a lower GC-content than the progenitor genome. In cholera and many other Gram-negative enterics, AT-rich DNA is bound by the H-NS protein immediately upon entrance into the cell, silencing the expression of this potentially toxic DNA. In other enterics, some proteins can remove H-NS from the DNA, allowing the cell to probe these novel genes, while others can interact with H-NS to maintain regulatory control and ensure derepression only happens when appropriate. However, such interactions with H-NS have not been observed in V. cholerae. Here, we discover and characterization of the genetic relationships between H-NS and an H-NS antagonist (ToxR, an essential protein for virulence), as well as an H-NS enhancer (TsrA, a poorly understood protein) in V. cholerae. ToxR is known to be a master activator of virulence, but we demonstrate that ToxR’s critical role is not direct activation, but rather to antagonize H-NS binding at shared binding loci related to host colonization and biofilm formation. Furthermore, TsrA, previously shown to be involved in regulation of type-VI secretion, was detected through immunoprecipitation of H-NS, followed by LC-MS/MS. Subsequent genetic analyses revealed that TsrA enhances H-NS repression of virulence genes on HAIs. Interestingly, TsrA enhances H-NS enrichment at areas of low-GC content, similar to the H-NS interactors in other enterics that V. cholerae was thought to lack. TsrA deletion also affects uptake of a mobile genetic element, establishing the first Vibrio-specific modulator of H-NS function that influences the regulation and acquisition of virulence-defining genetic elements. Knowledge of these interactions sheds light on HNS’ role in defining the virulence potential of V. cholerae and reveals a novel H-NS interactor similar to those present in other Gram-negative bacteria
Author: William S. Jermyn Publisher: ISBN: Category : Microbiology Languages : en Pages : 177
Book Description
Vibrio cholerae is a Gram negative, curved rod shaped bacterium and is ubiquitous in marine an estuarine environments. V. cholerae is the etiological agent of the profuse, secretory diarrheal disease cholera. Two critical virulence factors, the toxin coregulated pilin (TCP) and cholera toxin (CT) is responsible for the pathogenicity of the bacterium. Both virulence factors are encoded on mobile genetic elements that can be transferred to non-pathogenic strains, enabling these strains to colonise and cause disease. The genes encoding the TCP pilin are located on the Vibrio pathogenicity island; whereas the CT genes are encoded on a filamentous bacteriophage CTX. Neuraminidase is a virulence factor that is thought to act synergistically with CT, by increasing the numbers of receptors available for CT binding. Numerous reports have suggested that neuraminidase is horizontally transferred in bacteria, for example the carriage of the nanH gene on Fels-1 bacteriophage in Salmonella typhimurium LT2. The aim of this thesis was to examine the mechanism of horizontal transfer of nanH in V. cholerae. Molecular and bioinformatics analyses revealed that nanH is encoded on a second pathogenicity island in V. cholerae, which was subsequently named Vibrio pathogenicity island-2 (VPI-2). The island is 57.3 kb in size and consists of three distinct regions; a type-1 restriction modification system, a nan-nag region and a Mu phage-like region. VPI-2 exhibits many of the characteristics of pathogenicity islands such as being located adjacent to a tRNA gene and is found predominantly in pathogenic strains. Interestingly, the island is also prevalent in V. mimicus, a species of Vibrio that is closely related to V. cholerae. The VPI-2 is inserted into the same chromosomal site in both species, adjacent to a tRNA serine and consists of both the nan-nag and Mu phage regions. Intriguingly, the Mu phage region is predominantly associated with clinical isolates whereas the nan-nag region is prevalent in both clinical and environmental isolates. Multi locus sequence analysis indicates that the VPI-2 has recently been transferred between the two species.
Author: Kaye Wachsmuth Publisher: ISBN: Category : Cholera Languages : en Pages : 488
Book Description
Presents the latest molecular studies of virulence, colonization, gene regulation, and the O1 antigen. Gives an in-depth and analytical approach to the epidemiology of cholera that includes outbreak investigations, case-control studies, and surveillance functions. Describes the molecular approach to epidemiologic problems and questions. Tracks the global spread of cholera by genetically defining individual strains. Addresses possible intervention and prevention strategies, including the latest vaccines, and their public health relevance.
Author: Rita R Colwell Publisher: Frontiers E-books ISBN: 288919289X Category : Microbiology Languages : en Pages : 240
Book Description
Vibrios are Gram-negative bacilli that occur naturally in marine, estuarine, and freshwater systems. Some species include human and animal pathogens capable of causing gastroenteritis, wound infections, cholera, and fatal septicemia. Over the past decades, cutting edge research on Vibrio genomics has promoted a tremendous advance in our knowledge of these pathogens. Significant developments include the discovery of emerging epidemic clones, tracking the spread of new strain variants, and an intensified appreciation of the role of mobile genetic elements in antibiotic resistance spread as well as pathogenesis. Furthermore, improved understanding of the interaction of Vibrios with a variety of living organisms in the aquatic environment has documented the significant role of environmental reservoirs in their seasonal cycle favoring persistence of the pathogen during inter-epidemic periods and enhancing disease transmission. This Research Topic is dedicated to our current understanding in these areas and will bring together leading experts in the field to provide a deep overview of Vibrios ecology and evolution, and will suggest the pathway of future research in this field.
Author: Institute of Medicine Publisher: National Academies Press ISBN: 0309131219 Category : Science Languages : en Pages : 330
Book Description
Dr. Joshua Lederberg - scientist, Nobel laureate, visionary thinker, and friend of the Forum on Microbial Threats - died on February 2, 2008. It was in his honor that the Institute of Medicine's Forum on Microbial Threats convened a public workshop on May 20-21, 2008, to examine Dr. Lederberg's scientific and policy contributions to the marketplace of ideas in the life sciences, medicine, and public policy. The resulting workshop summary, Microbial Evolution and Co-Adaptation, demonstrates the extent to which conceptual and technological developments have, within a few short years, advanced our collective understanding of the microbiome, microbial genetics, microbial communities, and microbe-host-environment interactions.
Author: Hervé Tettelin Publisher: Springer Nature ISBN: 3030382818 Category : Science Languages : en Pages : 311
Book Description
This open access book offers the first comprehensive account of the pan-genome concept and its manifold implications. The realization that the genetic repertoire of a biological species always encompasses more than the genome of each individual is one of the earliest examples of big data in biology that opened biology to the unbounded. The study of genetic variation observed within a species challenges existing views and has profound consequences for our understanding of the fundamental mechanisms underpinning bacterial biology and evolution. The underlying rationale extends well beyond the initial prokaryotic focus to all kingdoms of life and evolves into similar concepts for metagenomes, phenomes and epigenomes. The book’s respective chapters address a range of topics, from the serendipitous emergence of the pan-genome concept and its impacts on the fields of microbiology, vaccinology and antimicrobial resistance, to the study of microbial communities, bioinformatic applications and mathematical models that tie in with complex systems and economic theory. Given its scope, the book will appeal to a broad readership interested in population dynamics, evolutionary biology and genomics.
Author: T. Ramamurthy Publisher: Springer Science & Business Media ISBN: 1603272658 Category : Medical Languages : en Pages : 368
Book Description
Though cholera is an ancient disease, its perennial occurrence in several parts of the world has attracted many researches to find ways and means to combat the disease. The prevailing seventh pandemic cholera is dominating since 1961, but the dimension of the disease has taken several silhouettes, as the genetic structure and functions of the Vibrio cholerae has changed to a great extent. Several recent studies have shown that transformation of the pathogen at the molecular level has ameliorated several cholera outbreaks and epidemics of with successive new clones of V. cholerae. This comprehensive compilation, written by eminent international researchers reviews the epidemiology of cholera in Africa, Asia, Russia and Latin Americas. The other chapters contributed by acclaimed authors cover various aspects on evolution, polysaccaharide biosynthesis, SXT element, integrons, small molecule signalling systems, flagellar synthesis, filamentous phages, pathogenic role of proteases and hemolysin, and other putative virulence factors. In addition, ecology of V. cholerae and management of cholera were also discussed in detail. This book will be good source of information to all researchers with interests in infectious diseases, microbiology and molecular biology.
Author: Yvonne Ann O'Shea
Author: Yvonne Ann O'Shea
Author: Aaron Ross Conrado
Author: Rita R. Colwell
Author: William S. Jermyn
Author: Kaye Wachsmuth
Author: Rita R Colwell
Author: Institute of Medicine
Author: Fabiano Lopes Thompson
Author: Hervé Tettelin
Author: T. Ramamurthy