Stressed bacteria can enter a dormant viable but non-culturable (VBNC) state. VBNC pathogens pose an increased health risk as they are undetectable by growth-based techniques and can wake up back into a virulent state. Although widespread in bacteria, the mechanisms governing this phenotypic switch remain elusive.
View Article and Find Full Text PDFL. monocytogenes causes listeriosis, a foodborne disease that is particularly dangerous for immunocompromised individuals and fetuses. Several virulence factors of this bacterial pathogen belong to a family of leucine-rich repeat (LRR)-containing proteins called internalins.
View Article and Find Full Text PDFis an opportunistic pathogen that causes a range of devastating diseases including chronic osteomyelitis, which partially relies on the internalization and persistence of in osteoblasts. The identification of the mechanisms of the osteoblast response to intracellular is thus crucial to improve the knowledge of this infectious pathology. Since the signal from specifically infected bacteria-bearing cells is diluted and the results are confounded by bystander effects of uninfected cells, we developed a novel model of long-term infection.
View Article and Find Full Text PDFMany bacterial species, including several pathogens, can enter a so-called "viable but non-culturable" (VBNC) state when subjected to stress. Bacteria in the VBNC state are metabolically active but have lost their ability to grow on standard culture media, which compromises their detection by conventional techniques based on bacterial division. Under certain conditions, VBNC bacteria can regain their growth capacity and, for pathogens, their virulence potential, through a process called resuscitation.
View Article and Find Full Text PDFcauses severe foodborne illness in pregnant women and immunocompromised individuals. After the intestinal phase of infection, the liver plays a central role in the clearance of this pathogen through its important functions in immunity. However, recent evidence suggests that during long-term infection of hepatocytes, a subpopulation of may escape eradication by entering a persistence phase in intracellular vacuoles.
View Article and Find Full Text PDFA mutant of ScottA with a transposon in the 5' untranslated region of the gene was identified to be hypersensitive to the antimicrobial -cinnamaldehyde. Here, we report the functional characterization of AsnB in peptidoglycan (PG) modification and intracellular infection. While AsnB of is annotated as a glutamine-dependent asparagine synthase, sequence alignment showed that this protein is closely related to a subset of homologs that catalyze the amidation of -diaminopimelic acid (DAP) residues in the peptidoglycan of other bacterial species.
View Article and Find Full Text PDFThe pathogen Listeria monocytogenes is a facultative intracellular bacterium, which targets a large range of cell types. Following entry, bacteria disrupt the invasion vacuole and reach the cytoplasm where they replicate and use the actin cytoskeleton to propel themselves from cell to cell. Mammalian epithelial cells grown in vitro can be used to study the different steps of the intracellular life of Listeria.
View Article and Find Full Text PDFToxins (Basel)
March 2020
Pathogenic bacteria secrete a variety of proteins that manipulate host cell function by targeting components of the plasma membrane, cytosol, or organelles. In the last decade, several studies identified bacterial factors acting within the nucleus on gene expression or other nuclear processes, which has led to the emergence of a new family of effectors called "nucleomodulins". In human and animal pathogens, for Gram-positive bacteria and , , , and for Gram-negative bacteria, have led to pioneering discoveries.
View Article and Find Full Text PDFBy modifying the host cell transcription programme, pathogenic bacteria disrupt a wide range of cellular processes and take control of the host's immune system. Conversely, by mobilising a network of defence genes, the host cells trigger various responses that allow them to tolerate or eliminate invaders. The study of the molecular basis of this crosstalk is crucial to the understanding of infectious diseases.
View Article and Find Full Text PDFIntracellular bacterial pathogens are generally classified into two types: those that exploit host membrane trafficking to construct specific niches in vacuoles (i.e., "vacuolar pathogens"), and those that escape from vacuoles into the cytosol, where they proliferate and often spread to neighboring cells (i.
View Article and Find Full Text PDFListeria monocytogenes causes listeriosis, a foodborne disease that poses serious risks to fetuses, newborns and immunocompromised adults. This intracellular bacterial pathogen proliferates in the host cytosol and exploits the host actin polymerization machinery to spread from cell-to-cell and disseminate in the host. Here, we report that during several days of infection in human hepatocytes or trophoblast cells, L.
View Article and Find Full Text PDFCurr Top Microbiol Immunol
August 2017
Bacterial surface proteins constitute an amazing repertoire of molecules with important functions such as adherence, invasion, signalling and interaction with the host immune system or environment. In Gram-positive bacteria, many surface proteins of the "LPxTG" family are anchored to the peptidoglycan (PG) by an enzyme named sortase. While this anchoring mechanism has been clearly deciphered, less is known about the spatial organization of cell wall-anchored proteins in the bacterial envelope.
View Article and Find Full Text PDFISG15 is an interferon-stimulated, linear di-ubiquitin-like protein, with anti-viral activity. The role of ISG15 during bacterial infection remains elusive. We show that ISG15 expression in nonphagocytic cells is dramatically induced upon Listeria infection.
View Article and Find Full Text PDFType I interferon responses are considered the primary means by which viral infections are controlled in mammals. Despite this view, several pathogens activate antiviral responses in the absence of type I interferons. The mechanisms controlling type I interferon-independent responses are undefined.
View Article and Find Full Text PDFFront Cell Infect Microbiol
January 2015
Interferons (IFNs) are secreted proteins of the cytokine family that regulate innate and adaptive immune responses to infection. Although the importance of IFNs in the antiviral response has long been appreciated, their role in bacterial infections is more complex and is currently a major focus of investigation. This review summarizes our current knowledge of the role of these cytokines in host defense against the bacterial pathogen Listeria monocytogenes and highlights recent discoveries on the molecular mechanisms evolved by this intracellular bacterium to subvert IFN responses.
View Article and Find Full Text PDFFor nearly 3 decades, listeriologists and immunologists have used mainly three strains of the same serovar (1/2a) to analyze the virulence of the bacterial pathogen Listeria monocytogenes. The genomes of two of these strains, EGD-e and 10403S, were released in 2001 and 2008, respectively. Here we report the genome sequence of the third reference strain, EGD, and extensive genomic and phenotypic comparisons of the three strains.
View Article and Find Full Text PDFUnlabelled: The nucleus has emerged as a key target for nucleomodulins, a family of effectors produced by bacterial pathogens to control host transcription or other nuclear processes. The virulence factor LntA from Listeria monocytogenes stimulates interferon responses during infection by inhibiting BAHD1, a nuclear protein involved in gene silencing by promoting heterochromatin formation. So far, whether the interaction between LntA and BAHD1 is direct and sufficient for inhibiting BAHD1 activity is unknown.
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