Identification and characterization of novel Salmonella mobile elements involved in the dissemination of genes linked to virulence and transmission.

Lorraine Doralys Rodriguez-Rivera's picture
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TitleIdentification and characterization of novel Salmonella mobile elements involved in the dissemination of genes linked to virulence and transmission.
Publication TypeJournal Article
Year of Publication2012
AuthorsSwitt, AIMoreno, Bakker, HC den, Cummings, CA, Rodriguez-Rivera, LD, Govoni, G, Raneiri, ML, Degoricija, L, Brown, S, Hoelzer, K, Peters, JE, Bolchacova, E, Furtado, MR, Wiedmann, M
JournalPloS One
Paginatione41247 - e41247
Date Published2012/01//
ISBN Number2009344591975
KeywordsAnimals, Bacterial, Bacterial: genetics, Drug Resistance, Gene Order, Gene Transfer, Genes, Genome, Genomic Islands, Horizontal, Interspersed Repetitive Sequences, Operon, Phylogeny, Plasmids, Plasmids: genetics, Prophages, Prophages: genetics, Salmonella, Salmonella Infections, Salmonella Infections: microbiology, Salmonella: classification, Salmonella: genetics, Salmonella: isolation & purification, Salmonella: pathogenicity, Viral, Virulence, Virulence: genetics
AbstractThe genetic diversity represented by >2,500 different Salmonella serovars provides a yet largely uncharacterized reservoir of mobile elements that can contribute to the frequent emergence of new pathogenic strains of this important zoonotic pathogen. Currently, our understanding of Salmonella mobile elements is skewed by the fact that most studies have focused on highly virulent or common serovars. To gain a more global picture of mobile elements in Salmonella, we used prediction algorithms to screen for mobile elements in 16 sequenced Salmonella genomes representing serovars for which no prior genome scale mobile element data were available. From these results, selected mobile elements underwent further analyses in the form of validation studies, comparative analyses, and PCR-based population screens. Through this analysis we identified a novel plasmid that has two cointegrated replicons (IncI1-IncFIB); this plasmid type was found in four genomes representing different Salmonella serovars and contained a virulence gene array that had not been previously identified. A Salmonella Montevideo isolate contained an IncHI and an IncN2 plasmid, which both encoded antimicrobial resistance genes. We also identified two novel genomic islands (SGI2 and SGI3), and 42 prophages with mosaic architecture, seven of them harboring known virulence genes. Finally, we identified a novel integrative conjugative element (ICE) encoding a type IVb pilus operon in three non-typhoidal Salmonella serovars. Our analyses not only identified a considerable number of mobile elements that have not been previously reported in Salmonella, but also found evidence that these elements facilitate transfer of genes that were previously thought to be limited in their distribution among Salmonella serovars. The abundance of mobile elements encoding pathogenic properties may facilitate the emergence of strains with novel combinations of pathogenic traits.