Search results for "Virulence"
showing 10 items of 457 documents
TpF1 from Treponema pallidum Activates Inflammasome and Promotes the Development of Regulatory T Cells
2011
Abstract Human syphilis is a multistage disease, with diverse and wide-ranging manifestations caused by Treponema pallidum. Despite the fact that a cell-mediated immune response takes part in the course of syphilis, T. pallidum often manages to evade host immunity and, in untreated individuals, may trigger chronic infection. With this study, we demonstrate for the first time, to our knowledge, that Treponema pallidum induces a regulatory T (Treg) response in patients with secondary syphilis and we found that the miniferritin TpF1, produced by the bacterium, is able to expand this response and promote the production of TGF-β. Accordingly, TpF1 stimulates monocytes to release IL-10 and TGF-β,…
Phenotypic and genetic analysis of biofilm formation by Staphylococcus epidermidis.
2012
Objective. The most important virulence factor of Staphylococcus epidermidis is their capability to form a biofilm on the surfaces of implanted medical devices. The accumulative phase of biofilm formation is linked to the production of intercellular adhesin encoded by the icaADBC operon and accumulation-associated protein by the aap gene. The aim of the study was to investigate biofilm formation phenotypically and genetically in clinical strains of S. epidermidis in comparison with commensal strains. Material and Methods. The study was carried out in 4 hospitals in Riga, Latvia. In total, 105 clinical strains of Staphylococcus epidermidis isolated from patients’ blood (n=67) and intravenous…
A 66-kilodalton heat shock protein of Salmonella typhimurium is responsible for binding of the bacterium to intestinal mucus
1992
Salmonella typhimurium infections have increased during the last few years. However, the interplay of virulence factors in S. typhimurium pathogenesis is still poorly understood, particularly with regard to the mechanisms and components of the bacterium which are involved in its interaction with the intestinal mucus. We have observed that S. typhimurium is aggregated by incubation with colonic mucus (guinea pig model). To quantify this phenomenon, an aggregation assay was established. By using this assay, it was found that the aggregation profile of S. typhimurium strains freshly isolated from patients (age 9 and older) with salmonellosis correlated with the severity of the disease. An isol…
Treatment-associated polymorphisms in protease are significantly associated with higher viral load and lower CD4 count in newly diagnosed drug-naive …
2012
Background: The effect of drug resistance transmission on disease progression in the newly infected patient is not well understood. Major drug resistance mutations severely impair viral fitness in a drug free environment, and therefore expected to revert quickly. Compensatory mutations, often already polymorphic in wild-type viruses, do not tend to revert after transmission. While compensatory mutations increase fitness during treatment, their presence may also modulate viral fitness and virulence in absence of therapy and major resistance mutations. We previously designed a modeling technique that quantifies genotypic footprints of in vivo treatment selective pressure, including both drug …
Prevalence of virulence-associated genotypes of Helicobacter pylori and correlation with severity of gastric pathology in patients from western Sicil…
2008
In a bacterium like Helicobacter pylori, which is characterized by a recombinant population structure, the associated presence of genes encoding virulence factors might be considered an expression of a selective advantage conferred to strains with certain genotypes and, therefore, a potentially useful tool for predicting the clinical outcome of infections. However, differences in the geographical and ethnic prevalence of the H. pylori virulence-associated genotypes can affect their clinical predictive value and need to be considered in advance. In this study we carried out such an evaluation in a group of patients living in Sicily, the largest and most populous island in the Mediterranean S…
RNA2-encoded VP37 protein of Broad bean wilt virus 1 is a determinant of pathogenicity, host susceptibility, and a suppressor of post-transcriptional…
2020
Abstract Broad bean wilt virus 1 (BBWV‐1, genus Fabavirus, family Secoviridae) is a bipartite, single‐stranded positive‐sense RNA virus infecting many horticultural and ornamental crops worldwide. RNA1 encodes proteins involved in viral replication whereas RNA2 encodes two coat proteins (the large and small coat proteins) and two putative movement proteins (MPs) of different sizes with overlapping C‐terminal regions. In this work, we determined the role played by the small putative BBWV‐1 MP (VP37) on virus pathogenicity, host specificity, and suppression of post‐transcriptional gene silencing (PTGS). We engineered a BBWV‐1 35S‐driven full‐length cDNA infectious clone corresponding to BBWV‐…
Relatedness affects competitive performance of a parasitic plant (Cuscuta europaea) in multiple infections.
2004
Theoretical models predict that parasite relatedness affects the outcome of competition between parasites, and the evolution of parasite virulence. We examined whether parasite relatedness affects competition between parasitic plants (Cuscuta europaea) that share common host plants (Urtica dioica). We infected hosts with two parasitic plants that were either half-siblings or nonrelated. Relative size asymmetry between the competing parasites was significantly higher in the nonrelated infections compared to infections with siblings. This higher asymmetry was caused by the fact that the performance of some parasite genotypes decreased and that of others increased when grown in multiple infect…
Molecular mechanisms of hookworm disease: stealth, virulence, and vaccines.
2012
Hookworms produce a vast repertoire of structurally and functionally diverse molecules that mediate their long-term survival and pathogenesis within a human host. Many of these molecules are secreted by the parasite, after which they interact with critical components of host biology, including processes that are key to host survival. The most important of these interactions is the hookworm's interruption of nutrient acquisition by the host through its ingestion and digestion of host blood. This results in iron deficiency and eventually the microcytic hypochromic anemia or iron deficiency anemia that is the clinical hallmark of hookworm infection. Other molecular mechanisms of hookworm infec…
Synthetic small molecules as anti-biofilm agents in the struggle against antibiotic resistance
2018
Abstract Biofilm formation significantly contributes to microbial survival in hostile environments and it is currently considered a key virulence factor for pathogens responsible for serious chronic infections. In the last decade many efforts have been made to identify new agents able to modulate bacterial biofilm life cycle, and many compounds have shown interesting activities in inhibiting biofilm formation or in dispersing pre-formed biofilms. However, only a few of these compounds were tested using in vivo models for their clinical significance. Contrary to conventional antibiotics, most of the anti-biofilm compounds act as anti-virulence agents as they do not affect bacterial growth. I…
Disruption of the Candida albicans ATC1 gene encoding a cell-linked acid trehalase decreases hypha formation and infectivity without affecting resist…
2007
In Candida albicans, the ATC1 gene, encoding a cell wall-associated acid trehalase, has been considered as a potentially interesting target in the search for new antifungal compounds. A phenotypic characterization of the double disruptant atc1Delta/atc1Delta mutant showed that it was unable to grow on exogenous trehalose as sole carbon source. Unlike actively growing cells from the parental strain (CAI4), the atc1Delta null mutant displayed higher resistance to environmental insults, such as heat shock (42 degrees C) or saline exposure (0.5 M NaCl), and to both mild and severe oxidative stress (5 and 50 mM H(2)O(2)), which are relevant during in vivo infections. Parallel measurements of int…