Cloning and molecular characterization of genes whose products allow Salmonella typhimurium to penetrate tissue culture cells.

Galán, Jorge E.; Curtiss, rd R

doi:10.1073/pnas.86.16.6383

Cited by 888 publications

(832 citation statements)

References 38 publications

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“…This model represents a robust, widely accepted and long studied assay system (Kihlstrom, 1977). Infection of epithelial cells involves SPI-1-dependent invasion which is followed by a phase of SPI-2-dependent intracellular replication (Galan and Curtiss, 1989;Garcia-del Portillo et al, 1993). Furthermore, the HeLa-S3 cell clone has recently been suggested by the ENCODE consortium as a preferred model cell line for various experimental setups and specific culture conditions were proposed to ensure comparability between different studies (Birney et al, 2007;Dunham et al, 2012).…”

Section: Choice Of the Infection Model And Optimization Of Infection mentioning

confidence: 99%

Dual RNA-seq of pathogen and host

2012

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SummaryThe infection of a eukaryotic host cell by a bacterial pathogen is one of the most intimate examples of cross-kingdom interactions in biology. Infection processes are highly relevant from both a basic research as well as a clinical point of view. Sophisticated mechanisms have evolved in the pathogen to manipulate the host response and vice versa host cells have developed a wide range of anti-microbial defense strategies to combat bacterial invasion and clear infections.However, it is this diversity and complexity that makes infection research so challenging to technically address as common approaches have either been optimized for bacterial or eukaryotic organisms. Instead, methods are required that are able to deal with the often dramatic discrepancy between host and pathogen with respect to various cellular properties and processes. One class of cellular macromolecules that exemplify this host-pathogen heterogeneity is given by their transcriptomes: Bacterial transcripts differ from their eukaryotic counterparts in many aspects that involve both quantitative and qualitative traits. The entity of RNA transcripts present in a cell is of paramount interest as it reflects the cell's physiological state under the given condition. Genome-wide transcriptomic techniques such as RNA-seq have therefore been used for single-organism analyses for several years, but their applicability has been limited for infection studies.The present work describes the establishment of a novel transcriptomic approach for infection biology which we have termed "Dual RNA-seq". Using this technology, it was intended to shed light particularly on the contribution of non-protein-encoding transcripts to virulence, as these classes have mostly evaded previous infection studies due to the lack of suitable methods. The performance of Dual RNA-seq was evaluated in an in vitro infection model based on the important facultative intracellular pathogen Salmonella enterica serovar Typhimurium and different human cell lines. Dual RNA-seq was found to be capable of capturing all major bacterial and human transcript classes and proved reproducible. During the course of these experiments, a previously largely uncharacterized bacterial small non-coding RNA (sRNA), referred to as STnc440, was identified as one of the most strongly induced genes in intracellular Salmonella.Interestingly, while inhibition of STnc440 expression has been previously shown to cause a virulence defect in different animal models of Salmonellosis, the underlying molecular mechanisms have remained obscure. Here, classical genetics, transcriptomics and biochemical assays proposed a complex model of Salmonella gene expression control that is orchestrated by this sRNA. In particular, STnc440 was found to be involved in the regulation of multiple bacterial target mRNAs by direct base pair interaction with consequences for Salmonella virulence and

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Section: Choice Of the Infection Model And Optimization Of Infection mentioning

confidence: 99%

Dual RNA-seq of pathogen and host

2012

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“…Also, rough strains of Typhi lost the capability to enter epithelial cells [50] while rough mutants of Typhimurium remained invasive [51]. Epithelial cell adhesion and invasion may not be uncoupled in Typhi, since all Typhi invasion mutants isolated in recent studies [47,52] were also adhesion-defective, whereas mutants obtained from UR serotypes like Typhimurium and Enteritidis were found to adhere to cell monolayers but invaded significantly less [53][54][55]. In particular, Weinstein and colleagues have recently shown that null mutations of in A and in E genes, identified as necessary for invasion but not for adhesion in Typhimurium, abolished both properties in Typhi [47].…”

Section: Typhimentioning

confidence: 99%

Host adapted serotypes of Salmonella enterica

et al. 2000

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Salmonella constitutes a genus of zoonotic bacteria of worldwide economic and health importance. The current view of salmonella taxonomy assigns the members of this genus to two species: S. enterica and S. bongori. S. enterica itself is divided into six subspecies, enterica, salamae, arizonae, diarizonae, indica, and houtenae, also known as subspecies I, II, IIIa, IIIb, IV, and VI, respectively [1]. Members of Salmonella enterica subspecies enterica are mainly associated with warm-blooded vertebrates and are usually transmitted by ingestion of food or water contaminated by infected faeces. The pathogenicity of most of the distinct serotypes remains undefined, and even within the most common serotypes, many questions remain to be answered regarding the interactions between the organism and the infected host.Salmonellosis manifests itself in three major forms: enteritis, septicaemia, and abortion, each of which may be present singly or in combination, depending on both the serotype and the host involved. Although currently over 2300 serovars of Salmonella are recognized, only about 50 serotypes are isolated in any significant numbers as human or animal pathogens [2, 3] and they all belong to subspecies enterica. Of these, most cause acute gastroenteritis characterized by a short incubation period and a severe systemic disease in man or animals, characterized by septicaemia, fever and/or abortion, and such serotypes are often associated with one or few host species [4–6].It is the intention of this review to present a summary of current knowledge of these host-adapted serotypes of S. enterica. The taxonomic relationships between the serotypes will be discussed together with a comparison of the pathology and pathogenesis of the disease that they cause in their natural host(s). Since much of our knowledge on salmonellosis is based on the results of work on Typhimurium, this serotype will often be used as the baseline in discussion. It is hoped that an appreciation of the differences that exist in the way these serotypes interact with the host will lead to a greater understanding of the complex host–parasite relationship that characterizes salmonella infections.

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“…Salmonella can invade macrophages in vitro and induce apoptosis through activation of caspase 1 by the Salmonella SipB protein encoded in the invasion locus of Salmonella pathogenicity island 1 (SPI1) (Hersh et al, 1999). Because invasion-de®cient mutants are still virulent in systemic Salmonella infections, the role of this SipB-mediated effect on macrophages is unclear in the pathogenesis of disseminated disease (Gala Â n and Curtiss, 1989). OmpR, a global response regulator of a two-component regulatory system in Salmonella, is required both for macrophage cytopathology in vitro and for systemic virulence in vivo (Lindgren et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

The Salmonella virulence plasmid spv genes are required for cytopathology in human monocyte-derived macrophages

et al. 2000

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SummaryThe pathogenesis of serious systemic Salmonella infections is characterized by survival and proliferation of bacteria inside macrophages. Infection of human monocyte-derived macrophages in vitro with S. typhimurium or S. dublin produces cytopathology characterized by detachment of cells that contain large numbers of proliferating bacteria. This cytopathology is dependent on the expression of the bacterial spv genes, a virulence locus previously shown to markedly enhance the ability of Salmonella to produce systemic disease. After 24 h of infection, macrophage cultures contain two populations of bacteria: (i) proliferating organisms present in a detached cell fraction; and (ii) a static bacterial population in macrophages remaining attached to the culture well. Mutations in either the essential transcriptional activator SpvR or the key SpvB protein markedly reduce the cytopathic effect of Salmonella infection. The spvdependent cytopathology in macrophages exhibits characteristics of apoptosis, with release of nucleosomes into the cytoplasm, nuclear condensation and DNA fragmentation. The current ®ndings suggest that the mechanism of the spv effect is through induction of increased cytopathology in host macrophages.

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Cloning and molecular characterization of genes whose products allow Salmonella typhimurium to penetrate tissue culture cells.

Cited by 888 publications

References 38 publications

Dual RNA-seq of pathogen and host

Dual RNA-seq of pathogen and host

Host adapted serotypes of Salmonella enterica

The Salmonella virulence plasmid spv genes are required for cytopathology in human monocyte-derived macrophages

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