Only one of the two type VI secretion systems encoded in the Salmonella enterica serotype Dublin genome is involved in colonization of the avian and murine hosts

David Pezoa, Carlos J. Blondel, Cecilia A. Silva, Hee Jeong Yang, Helene Andrews-Polymenis, Carlos A. Santiviago, Inés Contreras

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)

Abstract

The type VI secretion system (T6SS) is a virulence factor for many Gram-negative bacteria. Salmonella genus harbors five phylogenetically distinct T6SS loci encoded in Salmonella Pathogenicity Islands (SPIs) SPI-6, SPI-19, SPI-20, SPI-21 and SPI-22, which are differentially distributed among serotypes. The T6SSs encoded in SPI-6 and SPI-19 contribute to pathogenesis of serotypes Typhimurium and Gallinarum in mice and chickens, respectively. Salmonella Dublin is a pathogen restricted to cattle where it causes a systemic disease. Also, it can colonize other hosts such as chickens and mice, which can act as reservoirs of this serotype. Salmonella Dublin harbors the genes for both T6SS SPI-6 and T6SSSPI-19. This study has determined the contribution of T6SSSPI-6 and T6SSSPI-19 to host-colonization by Salmonella Dublin using avian and murine models of infection. Competitive index experiments showed that, a mutant strain lacking both T6SSs (T6SSSPI-6/T6SSSPI-19) presents a strong colonization defect in cecum of chickens, similar to the defect observed for the T6SSSPI-6 mutant, suggesting that this serotype requires a functional T6SSSPI-6 for efficient colonization of the avian gastrointestinal tract. Colonization of mice was also defective, although to a lesser extent than in chickens. In contrast, the T6SSSPI-19 was not necessary for colonization of either chickens or mice. Transfer of T6SS SPI-6, but not T6SSSPI-19, restored the ability of the double mutant to colonize both animal hosts. Our data indicate that Salmonella Dublin requires only the T6SSSPI-6 for efficient colonization of mice and chickens, and that the T6SSSPI-6 and T6SSSPI-19 are not functionally redundant.

Original languageEnglish
Article number2
JournalVeterinary Research
Volume45
Issue number1
DOIs
Publication statusPublished - 9 Jan 2014

ASJC Scopus subject areas

  • General Veterinary

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