The Type VI Secretion System Encoded in Salmonella Pathogenicity Island 19 Is Required for Salmonella enterica Serotype Gallinarum Survival within Infected MacrophagesReport as inadecuate




The Type VI Secretion System Encoded in Salmonella Pathogenicity Island 19 Is Required for Salmonella enterica Serotype Gallinarum Survival within Infected Macrophages - Download this document for free, or read online. Document in PDF available to download.

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Salmonella enterica serotype Gallinarum is the causative agent of fowl typhoid, a disease characterized by high morbidity andmortality that causes major economic losses in poultry production. We have reported that S. Gallinarum harbors a type VI secretionsystem T6SS encoded in Salmonella pathogenicity island 19 SPI-19 that is required for efficient colonization of chicks. Inthe present study, we aimed to characterize the SPI-19 T6SS functionality and to investigate the mechanisms behind the phenotypespreviously observed in vivo. Expression analyses revealed that SPI-19 T6SS core components are expressed and producedunder in vitro bacterial growth conditions. However, secretion of the structural-secreted components Hcp1, Hcp2, and VgrG tothe culture medium could not be determined, suggesting that additional signals are required for T6SS-dependent secretion ofthese proteins. In vitro bacterial competition assays failed to demonstrate a role for SPI-19 T6SS in interbacterial killing. In contrast,cell culture experiments with murine and avian macrophages RAW264.7 and HD11, respectively revealed production of agreen fluorescent protein-tagged version of VgrG soon after Salmonella uptake. Furthermore, infection of RAW264.7 and HD11macrophages with deletion mutants of SPI-19 or strains with genes encoding specific T6SS core components clpV and vgrGrevealed that SPI-19 T6SS contributes to S. Gallinarum survival within macrophages at 20 h postuptake. SPI-19 T6SS functionwas not linked to Salmonella-induced cytotoxicity or cell death of infected macrophages, as has been described for other T6SS.Our data indicate that SPI-19 T6SS corresponds to a novel tool used by Salmonella to survive within host cells.Nota general

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Author: Blondel, Carlos J.; - Jiménez, Juan C.; - Leiva, Lorenzo E.; - Álvarez Armijo, Sergio Aníbal; - Pinto, Bernardo I.; - Contrera

Source: http://repositorio.uchile.cl/



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