Evolution of Vibrio cholerae and Cholera Epidemics

Shah M. Faruque; John J. Mekalanos

doi:10.1128/9781555815639.ch30

Chapter 30 : Evolution of Vibrio cholerae and Cholera Epidemics

Authors: Shah M. Faruque¹, John J. Mekalanos²

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Affiliations: 1: Molecular Genetics Laboratory, International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh; 2: Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115

Content Type: Monograph

Publication Year: 2008

Category: Fungi and Fungal Pathogenesis; Bacterial Pathogenesis

Book DOI: 10.1128/9781555815639

Chapter DOI: 10.1128/9781555815639.ch30

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Abstract:

Of more than 200 known serogroups of Vibrio cholerae, only strains of O1 or O139 serogroups cause cholera epidemics. This chapter summarizes information on the evolution of pathogenic V. cholerae with an insight into the significance of virulence factors being encoded by accessory genetic elements, and phages, and into factors associated with the generation of diversity among virulent strains. Although this amazing transformation of V. cholera strains associated with epidemics was observed only once in nearly two centuries of recorded history of cholera, this period is not too long in an evolutionary time frame. Paradoxically, besides virulence genes and genetic elements mediating their transfer, the most important contributor to the evolution of pathogenic V. cholera is the human host itself, which supports the selective enrichment of diverse pathogenic strains. Overall, these molecular epidemiological studies indicated that there are temporal variations in the clones involved with cholera epidemics in particular geographical regions. Phage predation in the environment influences the temporal dynamics of cholera epidemics. The continual emergence of new strains of toxigenic V. cholera and their selective enrichment during cholera outbreaks constitute an essential component of the ecosystem for the survival and evolution of V. cholera and the genetic elements that mediate the transfer of virulence genes. Such studies offer the opportunity to expand our understanding of the phylogenic relationships between pathogenic and nonpathogenic strains of V. cholera and the discovery of new genes that may be involved directly or indirectly in the evolution of pathogenic V. cholera.

Citation: Faruque S, Mekalanos J. 2008. Evolution of Vibrio cholerae and Cholera Epidemics, p 361-371. In Baquero F, Nombela C, Cassell G, Gutiérrez-Fuentes J (ed), Evolutionary Biology of Bacterial and Fungal Pathogens. ASM Press, Washington, DC. doi: 10.1128/9781555815639.ch30

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