Publications by authors named "Marion Dorer"

grows within cells ranging from environmental amoebae to human macrophages. In spite of this conserved strategy of pathogenesis, identification of host factors that restrict intracellular replication has not been extended outside components of the mammalian innate immune response. We performed a double-stranded RNA (dsRNA) screen against more than 50% of the annotated open reading frames (ORFs) to identify host cell factors that restrict The majority of analyzed dsRNAs that stimulated intracellular replication were directed against host proteins involved in protein synthesis or cell cycle control.

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Interactions between hosts and pathogens are complex, so understanding the events that govern these interactions requires the analysis of molecular mechanisms operating in both organisms. Many pathogens use multiple strategies to target a single event in the disease process, confounding the identification of the important determinants of virulence. We developed a genetic screening strategy called insertional mutagenesis and depletion (iMAD) that combines bacterial mutagenesis and RNA interference, to systematically dissect the interplay between a pathogen and its host.

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Animal models are important tools for studies of human disease, but developing these models is a particular challenge with regard to organisms with restricted host ranges, such as the human stomach pathogen Helicobacter pylori. In most cases, H. pylori infects the stomach for many decades before symptoms appear, distinguishing it from many bacterial pathogens that cause acute infection.

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Article Synopsis
  • All organisms have mechanisms to repair their DNA, which is crucial for their survival and the survival of their offspring; these mechanisms can also lead to genetic diversity.
  • Sequencing of bacteria has shown significant genetic variation even within the same species, emphasizing the need to understand how DNA recombination and repair work.
  • Helicobacter pylori, a pathogen that infects the human stomach, is a valuable model for studying these processes due to its capacity for genetic diversification through recombination and repair pathways.
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Helicobacter pylori is a genetically diverse bacterial species, owing in part to its natural competence for DNA uptake that facilitates recombination between strains. Inter-strain DNA recombination occurs during human infection and the H. pylori genome is in linkage equilibrium worldwide.

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Many organisms respond to DNA damage by inducing expression of DNA repair genes. We find that the human stomach pathogen Helicobacter pylori instead induces transcription and translation of natural competence genes, thus increasing transformation frequency. Transcription of a lysozyme-like protein that promotes DNA donation from intact cells is also induced.

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Article Synopsis
  • The bacterium Helicobacter pylori, previously thought not to exist in the acidic environment of the stomach, was found to cause chronic diseases like peptic ulcers and gastric cancer, reshaping our understanding of the stomach's microbiome.
  • Unlike typical pathogens, H. pylori's role in disease involves complex interactions with the host and environment rather than just toxin production, highlighting its unique behavior as a carcinogen.
  • Research indicates that H. pylori has coevolved with humans and, while it can cause diseases, it may also offer protective effects, suggesting that eradicating it from asymptomatic individuals may not always be beneficial.
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Mutations in bacterial pathogens have been isolated using many strategies. In contrast, the hosts they attack are significantly less tractable. To overcome this problem, a number of model host systems have been developed for isolation and investigation of mutations that modulate pathogen growth.

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Legionella pneumophila translocates multiple bacterial effector proteins into host cells to direct formation of a replication vacuole for the bacterium. The emerging consensus is that formation of this compartment involves recruitment of membrane material that traffics between the endoplasmic reticulum (ER) and Golgi. To investigate this model, a targeted approach was used to knock down expression of proteins involved in membrane trafficking, using RNA interference in Drosophila cells.

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