background : salmonella actively stimulates its own uptake into the epithelial cells by inducing cytoskeleton rearrangements and membrane ruffling triggered by some proteins secreted by salmonella into the cytosol of the epithelial cells via a type iii secretion system (ttss) encoded by genes of the salmonella pathogenicity island 1 (spi-1). hila is a transcriptional activator encoded on salmon...

background :  young chickens are more susceptible to salmonella colonization than older ones that have developed resistance with age as native microflora become established.   methods :  in this study, two groups of fertile eggs were inoculated with 20 cfu of hila or parent strains of s . enteritidis . presence and number of salmonella cells inside the homogenized egg contents were determined on...

BACKGROUND: Several regulatory proteins are involved in Salmonella invasion. The key regulator of SPI-1 (Salmonella pathogenicity island 1 ) is hilA, a transcriptional activator encoded on SPI-1 that regulates the expression of the SPI-1 secretion system. OBJECTIVES: Importance of hilA mutation on S. enteritidis colonization and shedding in layer hens was evaluated in a long-term experiment. ME...

Iron is an essential element for the survival of living cells. However, excess iron is toxic, and its uptake is exquisitely regulated by the ferric uptake regulator, Fur. In Salmonella, the Salmonella pathogenicity island 1 (SPI-1) encodes a type three secretion system, which is required for invasion of host epithelial cells in the small intestine. A major activator of SPI-1 is HilA, which is e...

HilA activates the expression of Salmonella enterica serovar Typhimurium invasion genes. To learn more about regulation of hilA, we isolated Tn5 mutants exhibiting reduced hilA and/or invasion gene expression. In addition to expected mutations, we identified Tn5 insertions in pstS, fadD, flhD, flhC, and fliA. Analysis of the pstS mutant indicates that hilA and invasion genes are repressed by th...

Penetration of intestinal epithelial cells by Salmonella enterica serovar Typhimurium requires the expression of invasion genes, found in Salmonella pathogenicity island 1 (SPI1), that encode components of a type III secretion apparatus. These genes are controlled in a complex manner by regulators within SPI1, including HilA and InvF, and those outside SPI1, such as the two-component regulators...

The Salmonella enterica serovar Typhimurium HilA protein is the key regulator for the invasion of epithelial cells. By a combination of genome-wide location and transcript analysis, the HilA-dependent regulon has been delineated. Under invasion-inducing conditions, HilA binds to most of the known target genes and a number of new target genes. The sopB, sopE, and sopA genes, encoding effector pr...

background: several regulatory proteins are involved in salmonella invasion. the key regulator of spi-1 (salmonella pathogenicity island 1 ) is hila, a transcriptional activator encoded on spi-1 that regulates the expression of the spi-1 secretion system. objectives: importance of hila mutation on s. enteritidis colonization and shedding in layer hens was evaluated in a long-term experiment. me...

Salmonella enterica serovar Typhimurium invasion genes are necessary for bacterial invasion of intestinal epithelial cells and are thought to allow salmonellae to enter and cross the intestinal epithelium during infection. Many invasion genes are encoded on Salmonella pathogenicity island 1 (SPI1), and their expression is activated by HilA, a transcription factor also encoded on SPI1. We have s...

Leucine-responsive regulatory protein (Lrp) is a global gene regulator that influences expression of a large number of genes including virulence-related genes in Escherichia coli and Salmonella. No systematic studies examining the regulation of virulence genes by Lrp have been reported in Salmonella. We report here that constitutive expression of Lrp [lrp(Con)] dramatically attenuates Salmonell...