Virulence Factors in Salmonella Typhimurium: The Sagacity of a Bacterium

Santos, Anamaria M.P. dos; Ferrari, Rafaela Gomes; Conté-Júnior, Carlos Adam

doi:10.1007/s00284-018-1510-4

Cited by 106 publications

(92 citation statements)

References 102 publications

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“…Salmonella species are widely distributed and are the cause of gastroenteritis, diarrhea and typhoid fever around the globe [ 1 , 2 ]. These bacteria have a plethora of virulence factors mainly grouped in discrete genomic regions called Salmonella pathogenicity islands (SPIs) [ 3 , 4 ]. SPI-1 and SPI-2 each encode for a type three-secretion system (T3SS), T3SS-1 and T3SS-2, respectively.…”

Section: Introductionmentioning

confidence: 99%

The Salmonella Typhimurium InvF-SicA complex is necessary for the transcription of sopB in the absence of the repressor H-NS

et al. 2020

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Expression of virulence factors in non-typhoidal Salmonella enterica depends on a wide variety of general and specific transcriptional factors that act in response to multiple environmental signals. Expression of genes for cellular invasion located in the Salmonella pathogenicity island 1 (SPI-1) is tightly regulated by several transcriptional regulators arrayed in a cascade, while repression of this system is exerted mainly by H-NS. In SPI-1, H-NS represses the expression mainly by binding to the regulatory region of hilA and derepression is exercised mainly by HilD. However, the possible regulatory role of H-NS in genes downstream from HilD and HilA, such as those regulated by InvF, has not been fully explored. Here the role of H-NS on the expression of sopB , an InvF dependent gene encoded in SPI-5, was evaluated. Our data show that InvF is required for the expression of sopB even in the absence of H-NS. Furthermore, in agreement with previous results on other InvF-regulated genes, we found that the expression of sopB requires the InvF/SicA complex. Our results support that SicA is not required for DNA binding nor for increasing affinity of InvF to DNA in vitro . Moreover, by using a bacterial two-hybrid system we were able to identify interactions between SicA and InvF. Lastly, protein-protein interaction assays suggest that InvF functions as a monomer. Derived from these results we postulate that the InvF/SicA complex does not act on sopB as an anti-H-NS factor; instead, it seems to induce the expression of sopB by acting as a classical transcriptional regulator.

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Section: Introductionmentioning

confidence: 99%

The Salmonella Typhimurium InvF-SicA complex is necessary for the transcription of sopB in the absence of the repressor H-NS

et al. 2020

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“…It is important to mention that the ability of S . Typhimurium strains to invade and to survive in the host cells is closely linked to virulence genes present in the bacterium [ 30 ].…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, several essential genes for the pathogenesis of salmonellosis were identified in this study with high identity and coverage reinforcing the pathogenic potential of these strains. It is important to mention that the ability of S. Typhimurium strains to invade and to survive in the host cells is closely linked to virulence genes present in the bacterium [30].…”

Section: Plos Onementioning

confidence: 99%

“…Moreover, genes present in the SPI-3, SPI4 and SPI-5 are related to virulence of Salmonella spp. However, more studies are needed in this area, due to the lack of theoretical and scientific information [30]. For example, the pip (pipA, pipB, pipC and pipD) genes may be related to the rate of fluid secretion and inflammatory response during salmonellosis, suggesting that such genes are related to the bacterial enteropathogenicity, but the exact mechanism has not been yet fully elucidated [30,32].…”

Section: Plos Onementioning

confidence: 99%

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Phenotypic and genotypic characterization of Salmonella Typhimurium isolates from humans and foods in Brazil

et al. 2020

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Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) causes gastroenteritis in many countries. However, in Brazil there are few studies that have conducted a virulence characterization of this serovar. The aim of this study was to evaluate the virulence potential of S. Typhimurium strains isolated in Brazil. Forty S. Typhimurium strains isolated from humans (n = 20) and food (n = 20) from Brazil were studied regarding their invasion and survival in human epithelial cells (Caco-2) and macrophages (U937). Their virulence potential was determined using the Galleria mellonella larvae model combined with the analysis of virulence genes by whole genome sequencing (WGS). A total of 67.5% of the S. Typhimurium studied (32.5% isolated from humans and 35% isolated from food) invaded Caco-2 epithelial cells at levels similar to or greater than the S. Typhimurium SL1344 prototype strain. In addition, 37.5% of the studied strains (25% isolated from humans and 12.5% isolated from food) survived in U937 human macrophages at levels similar to or greater than SL1344. S. Typhimurium strains isolated from humans (40%) and food (25%) showed high or intermediate virulence in G. mellonella larvae after seven days exposure. Approximately, 153 virulence genes of chromosomal and plasmidial origin were detected in the strains studied. In conclusion, the ability of the S. Typhimurium to invade Caco-2 epithelial cells was strain dependent and was not related to the source or the year of isolation. However, S. Typhimurium strains isolated from humans showed greater survival rates in U937 human macrophages, and presented higher proportion of isolates with a virulent profile in G. mellonella in comparison to strains isolated from food suggesting that this difference may be related to the higher frequency of human isolates which contained plasmid genes, such as spvABCDR operon, pefABCD operon, rck and mig-5.

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“…The SPI-4 is a 25 kb large island needed for intra-macrophage survival and is likely to carry a type I secretion system involved in toxin secretion and apoptosis (Kiss et al, 2007). It is speculated that SPI-4 is associated with secretion of cytotoxin responsible for infecting macrophages and coding for non-fimbrial adhesins seen in several Salmonella species during intestinal phase of the disease (dos Santos et al, 2019). The sequence analysis of the ±11 kb (25cs) large SPI-5 revealed the presence of six genes, including the SopB, a gene encoding multiple TTSS effector proteins (Rychlik et al, 2009).…”

Section: Blue)mentioning

confidence: 99%

Mechanisms for Salmonella Infection and Potential Management Options in Chicken

2020

THE JAPS

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Salmonella enterica is the largest species in genus Salmonella with its serovars responsible for infection in chickens and other warm-blooded hosts. After oral ingestion, Salmonella penetrates the mucosal layer of the gastrointestinal tract (GIT). It then provokes gastroenteritis and systemic infection to chickens of all ages depending on the serovar involved. The paper explains about Salmonella infection via Type Three Secretion System (TTSS) encoded Pathogenicity Islands (PIs) and how the bacterium survives the acidic environment of GIT. It also explains the roles of TTSS-1 and TTSS-2 in translocation of effectors that interfere with host proteins and later internalisation of Salmonella in Salmonellacontaining vacuole (SCV). Other virulence factors such as plasmid, biofilm and lipopolysaccharides are highlighted, and their importance in inducing pathogenicity to host was also included in the paper. Therefore, several factors are geared toward survival, infection, and replication of Salmonella in the host cells. Hence, this article explains the mechanisms of Salmonella infection in chicken, its persistence in different environments and the approaches in controlling chicken salmonellosis.

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Virulence Factors in Salmonella Typhimurium: The Sagacity of a Bacterium

Cited by 106 publications

References 102 publications

The Salmonella Typhimurium InvF-SicA complex is necessary for the transcription of sopB in the absence of the repressor H-NS

The Salmonella Typhimurium InvF-SicA complex is necessary for the transcription of sopB in the absence of the repressor H-NS

Phenotypic and genotypic characterization of Salmonella Typhimurium isolates from humans and foods in Brazil

Mechanisms for Salmonella Infection and Potential Management Options in Chicken

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