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Comparative genomics of clinical and environmental Vibrio mimicus

Hasan, Nur A., Grim, Christopher J., Haley, Bradd J., Chun, Jongsik, Alam, Munirul, Taviani, Elisa, Hoq, Mozammel, Munk, A. Christine, Saunders, Elizabeth, Brettin, Thomas S., Bruce, David C., Challacombe, Jean F., Detter, J. Chris, Han, Cliff S., Xie, Gary, Nair, G. Balakrish, Huq, Anwar, Colwell, Rita R.
Proceedings of the National Academy of Sciences of the United States of America 2010 v.107 no.49 pp. 21134-21139
Vibrio cholerae, Vibrio mimicus, chromosomes, genes, genomics, hemagglutinins, hemolysins, open reading frames, pandemic, pathogenicity islands, phylogeny, viability, virulence, virulent strains
Whether Vibrio mimicus is a variant of Vibrio cholerae or a separate species has been the subject of taxonomic controversy. A genomic analysis was undertaken to resolve the issue. The genomes of V. mimicus MB451, a clinical isolate, and VM223, an environmental isolate, comprise ca. 4,347,971 and 4,313,453 bp and encode 3,802 and 3,290 ORFs, respectively. As in other vibrios, chromosome I (C-I) predominantly contains genes necessary for growth and viability, whereas chromosome II (C-II) bears genes for adaptation to environmental change. C-I harbors many virulence genes, including some not previously reported in V. mimicus, such as mannose-sensitive hemagglutinin (MSHA), and enterotoxigenic hemolysin (HlyA); C-II encodes a variant of Vibrio pathogenicity island 2 (VPI-2), and Vibrio seventh pandemic island II (VSP-II) cluster of genes. Extensive genomic rearrangement in C-II indicates it is a hot spot for evolution and genesis of speciation for the genus VIBRIO: The number of virulence regions discovered in this study (VSP-II, MSHA, HlyA, type IV pilin, PilE, and integron integrase, IntI4) with no notable difference in potential virulence genes between clinical and environmental strains suggests these genes also may play a role in the environment and that pathogenic strains may arise in the environment. Significant genome synteny with prototypic pre-seventh pandemic strains of V. cholerae was observed, and the results of phylogenetic analysis support the hypothesis that, in the course of evolution, V. mimicus and V. cholerae diverged from a common ancestor with a prototypic sixth pandemic genomic backbone.