Search results for "Host-Pathogen Interaction"
showing 10 items of 189 documents
Experimental virus evolution reveals a role of plant microtubule dynamics and TORTIFOLIA1/SPIRAL2 in RNA trafficking.
2014
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Invasion Ability and Disease Dynamics of Environmentally Growing Opportunistic Pathogens under Outside-Host Competition
2014
Most theories of the evolution of virulence concentrate on obligatory host-pathogen relationship. Yet, many pathogens replicate in the environment outside-host where they compete with non-pathogenic forms. Thus, replication and competition in the outside-host environment may have profound influence on the evolution of virulence and disease dynamics. These environmentally growing opportunistic pathogens are also a logical step towards obligatory pathogenicity. Efficient treatment methods against these diseases, such as columnaris disease in fishes, are lacking because of their opportunist nature. We present a novel epidemiological model in which replication and competition in the outside-hos…
Type-IIA secreted phospholipase A2 is an endogenous antibiotic-like protein of the host.
2010
International audience; Type-IIA secreted phospholipase A(2) (sPLA(2)-IIA) has been proposed to play a role in the development of inflammatory diseases. It has been shown to release arachidonic acid, the precursor of proinflammatory eicosanoids, to hydrolyze phospholipids of pulmonary surfactant, and to bind to specific receptors located on cell surface membranes. However, the most established biological role of sPLA(2)-IIA is related to its potent bactericidal property in particular toward Gram-positive bacteria. This enzyme is present in animal and human biological fluids at concentrations sufficient to kill bacteria. Human recombinant sPLA(2)-IIA is able to kill Gram-positive bacteria at…
Host–virus evolutionary dynamics with specialist and generalist infection strategies: Bifurcations, bistability, and chaos
2019
In this work, we have investigated the evolutionary dynamics of a generalist pathogen, e.g., a virus population, that evolves toward specialization in an environment with multiple host types. We have particularly explored under which conditions generalist viral strains may rise in frequency and coexist with specialist strains or even dominate the population. By means of a nonlinear mathematical model and bifurcation analysis, we have determined the theoretical conditions for stability of nine identified equilibria and provided biological interpretation in terms of the infection rates for the viral specialist and generalist strains. By means of a stability diagram, we identified stable fixed…
HCV genotype 5: an orphan virus
2013
HCV genotype 5 (HCV-5) is the least known HCV genotype. It is found mainly in South Africa and in restricted areas of Belgium, Spain, France, Syria and Greece. Sporadic cases are reported worldwide. The main modes of transmission are blood transfusion and iatrogenic causes. Little is known about its origin, but various studies have elucidated its spread worldwide. In endemic areas, patients infected with HCV-5 are on average older and have a higher viral load and more advanced fibrosis than those infected with non-HCV-5 genotypes. The current standard of care for HCV-5 chronic infection is 48 weeks of dual therapy with pegylated interferon plus ribavirin. ‘Favourable’ Il28B polymorphisms a…
Stochastic Episodes of Latent Cytomegalovirus Transcription Drive CD8 T-Cell “Memory Inflation” and Avoid Immune Evasion
2021
Acute infection with murine cytomegalovirus (mCMV) is controlled by CD8+ T cells and develops into a state of latent infection, referred to as latency, which is defined by lifelong maintenance of viral genomes but absence of infectious virus in latently infected cell types. Latency is associated with an increase in numbers of viral epitope-specific CD8+ T cells over time, a phenomenon known as “memory inflation” (MI). The “inflationary” subset of CD8+ T cells has been phenotyped as KLRG1+CD62L- effector-memory T cells (iTEM). It is agreed upon that proliferation of iTEM requires repeated episodes of antigen presentation, which implies that antigen-encoding viral genes must be transcribed du…
Evolutionary convergence and nitrogen metabolism in Blattabacterium strain Bge, primary endosymbiont of the cockroach Blattella germanica.
2009
Bacterial endosymbionts of insects play a central role in upgrading the diet of their hosts. In certain cases, such as aphids and tsetse flies, endosymbionts complement the metabolic capacity of hosts living on nutrient-deficient diets, while the bacteria harbored by omnivorous carpenter ants are involved in nitrogen recycling. In this study, we describe the genome sequence and inferred metabolism of Blattabacterium strain Bge, the primary Flavobacteria endosymbiont of the omnivorous German cockroach Blattella germanica. Through comparative genomics with other insect endosymbionts and free-living Flavobacteria we reveal that Blattabacterium strain Bge shares the same distribution of functio…
The transcription factor Interferon Regulatory Factor 4 is required for the generation of protective effector CD8 + T cells
2013
Robust cytotoxic CD8 + T-cell response is important for immunity to intracellular pathogens. Here, we show that the transcription factor IFN Regulatory Factor 4 (IRF4) is crucial for the protective CD8 + T-cell response to the intracellular bacterium Listeria monocytogenes . IRF4-deficient ( Irf4 −/− ) mice could not clear L. monocytogenes infection and generated decreased numbers of L. monocytogenes -specific CD8 + T cells with impaired effector phenotype and function. Transfer of wild-type CD8 + T cells into Irf4 −/− mice improved bacterial clearance, suggesting an intrinsic defect of CD8 + T cells in Irf4 −/− mice. Following transfer into wild-type recipients, Irf4 −/− CD8 + T cells bec…
Cellular interactions ofCandida albicanswith human oral epithelial cells and enterocytes
2010
The human pathogenic fungus Candida albicans can cause systemic infections by invading epithelial barriers to gain access to the bloodstream. One of the main reservoirs of C. albicans is the gastrointestinal tract and systemic infections predominantly originate from this niche. In this study, we used scanning electron and fluorescence microscopy, adhesion, invasion and damage assays, fungal mutants and a set of fungal and host cell inhibitors to investigate the interactions of C. albicans with oral epithelial cells and enterocytes. Our data demonstrate that adhesion, invasion and damage by C. albicans depend not only on fungal morphology and activity, but also on the epithelial cell type an…
Validation of the Tetracycline Regulatable Gene Expression System for the Study of the Pathogenesis of Infectious Disease
2011
Understanding the pathogenesis of infectious disease requires the examination and successful integration of parameters related to both microbial virulence and host responses. As a practical and powerful method to control microbial gene expression, including in vivo, the tetracycline-regulatable system has recently gained the favor of many investigative groups. However, some immunomodulatory effects of the tetracyclines, including doxycycline, could potentially limit its use to evaluate host responses during infection. Here we have used a well-established murine model of disseminated candidiasis, which is highly dependent on both the virulence displayed by the fungal cells and on the host im…