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Regulatory Mechanisms between Quorum Sensing and Virulence in Salmonella.

Salmonella is a foodborne pathogen that causes enterogastritis among humans, livestock and poultry, and it not only causes huge economic losses for the feed industry but also endangers public health around the world. However, the prevention and treatment of Salmonella infection has remained poorly developed because of its antibiotic resistance. Bacterial quorum sensing (QS) system is an intercellular cell-cell communication mechanism involving multiple cellular processes, especially bacterial virulence, such as biofilm formation, motility, adherence, and invasion. Therefore, blocking the QS sy…

Aspergillus fumigatus Acetate Utilization Impacts Virulence Traits and Pathogenicity.

Aspergillus fumigatus is a major opportunistic fungal pathogen of immunocompromised and immunocompetent hosts. To successfully establish an … extracellular carbon source, in this case glucose and acetate, significantly affected A. fumigatus virulence traits such as secondary metabolite secretion and cell wall composition, with the latter having consequences for resistance to oxidative stress, antifungal drugs, and human neutrophil-mediated killing. Furthermore, deletion of facB significantly imp …

Epigallocatechin gallate alters leukotoxin secretion and Aggregatibacter actinomycetemcomitans virulence.

OBJECTIVES: We and others have previously shown that epigallocatechin gallate (EGCg) inhibits the activity of an important virulence factor, leukotoxin (LtxA), produced by the oral bacterium Aggregatibacter actinomycetemcomitans, suggesting the potential use of this molecule as an anti-virulence strategy to treat periodontal infections. Here, we sought to better understand the effects of EGCg on toxin secretion and A. actinomycetemcomitans pathogenicity in a co-culture model. METHODS: We used a quantitative immunoblot assay to determine the concentrations of LtxA in the bacterial supernatant …

Вирусные детерминанты, которые движут Enterovirus-A71 фитнес и вирулентность.

Болезнь ручья, нога и мута (HFMD), как правило, является самоограничивающейся, мягкой детской болезнью, вызванной главным образом вирусом Коксаки А16 (CVA16) и Enterovirus A71 (EV-A71), которые являются членами семейства Пикорнавиридае. Однако повторяющиеся вспышки и эпидемии ГФМР в связи с инфекцией ЭВ-А71 в западной части Тихого океана и склонностью штаммов ЭВ-А71 вызывать серьезные неврологические осложнения сделали этот нейротропический вирус серьезной проблемой для здоровья населения в пострадавших странах. Высокие темпы мутации, ведущие к вирусным квазивидным явлениям в сочетании с часты

Совпадение в аннотации оригинала
Hand, Foot and Mouth Disease (HFMD) is usually a self-limiting, mild childhood disease that is caused mainly by Coxsackie virus A16 (CVA16) … hes have led to the identification of a number of viral determinants involved in EV-A71 fitness and virulence. These viral determinants include amino acid residues located in the structural proteins of the virus, affecting attachment to the host cell surface, receptor binding, and uncoating events. Critical residues in non-structural proteins have also been …

Bacterial virulence plays a crucial role in MRSA sepsis.

Bacterial sepsis is a major global cause of death. However, the pathophysiology of sepsis has remained poorly understood. In industrialized nations, Staphylococcus aureus represents the pathogen most commonly associated with mortality due to sepsis. Because of the alarming spread of antibiotic resistance, anti-virulence strategies are often proposed to treat staphylococcal sepsis. However, we do not yet completely understand if and how bacterial virulence contributes to sepsis, which is vital for a thorough assessment of such strategies. We here examined the role of virulence and quorum-sensin…

Silkworm model for Bacillus anthracis infection and virulence determination.

Bacillus anthracis is an obligate pathogen and a causative agent of anthrax. Its major virulence factors are plasmid-coded; however, recent studies have revealed chromosome-encoded virulence factors, indicating that the current understanding of its virulence mechanism is elusive and needs further investigation. In this study, we established a silkworm (Bombyx mori) infection model of B. anthracis. We showed that silkworms were killed by B. anthracis Sterne and cured of the infection when administered with antibiotics. We quantitatively determined the lethal dose of the bacteria that kills 50% …

Extraintestinal Pathogenic Escherichia coli: Virulence Factors and Antibiotic Resistance.

The One Health approach emphasizes the importance of antimicrobial resistance (AMR) as a major concern both in public health and in food animal production systems. As a general classification, E. coli can be distinguished based on the ability to cause infection of the gastrointestinal system (IPEC) or outside of it (ExPEC). Among the different pathogens, E. coli are becoming of great importance, and it has been suggested that ExPEC may harbor resistance genes that may be transferred to pathogenic or opportunistic bacteria. ExPEC strains are versatile bacteria that can cause urinary tract, bloo

Selection for Phage Resistance Reduces Virulence of Shigella flexneri.

There is an increasing interest in phage therapy as an alternative to antibiotics for treating bacterial infections, especially using phages that select for evolutionary trade-offs between increased phage resistance and decreased fitness traits, such as virulence, in target bacteria. A vast repertoire of virulence factors allows the opportunistic bacterial pathogen Shigella flexneri to invade human gut epithelial cells, replicate intracellularly, and evade host immunity through intercellular spread. It has been previously shown that OmpA is necessary for the intercellular spread of S. flexneri…

SARS-CoV-2-specific virulence factors in COVID-19.

The paucity of knowledge about severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific virulence factors has greatly hampered the therapeutic management of patients with coronavirus disease 2019 (COVID-19). Recently, a cluster of studies appeared, which presented empirical evidence for SARS-CoV-2-specific virulence factors that can explain key elements of COVID-19 pathology. These studies unravel multiple structural and nonstructural specifics of SARS-CoV-2, such as a unique FURIN cleavage site, papain-like protease (SCoV2-PLpro), ORF3b and nonstructural proteins, and dynamic con…

Granzyme B Attenuates Bacterial Virulence by Targeting Secreted Factors.

Pathogenic bacteria secrete virulence factors that interact with the human host to establish infections. The human immune system evolved multiple mechanisms to fight bacterial invaders, including immune proteases that were demonstrated to contribute crucially to antibacterial defense. Here we show that granzyme B degrades multiple secreted virulence mediators from Listeria monocytogenes, Salmonella typhimurium, and Mycobacteria tuberculosis. Pathogenic bacteria, when infected in the presence of granzyme B or granzyme-secreting killer cells, fail to grow in human macrophages and epithelial cell…

Virulence and Antibiotic Resistance Patterns in E. coli, Morocco.

Of 28 non-duplicate isolates of Escherichia coli recovered from yellow-legged Larus michahellis in Morocco, 92.86% were resistant to more than three antibiotics and 71.4% were multidrug resistant. Phylogenetic group A was most predominant (57.14%), followed by B1 (18%), B2 (14.28%) and F (10.71%). One isolate was resistant to ertapenem and contained the blaOXA-48 gene. The plasmid-mediated quinolone resistance determinants were detected in nine isolates (aac(6')-Ib-cr, qnrS1, qnrB1). Thirteen isolates carried one of the Shiga toxin E. coli-associated genes: stx1 (n = 6), stx2 (n = 5) and eae (

Activity and Functional Importance of Helicobacter pylori Virulence Factors.

Helicobacter pylori is a very successful Gram-negative pathogen colonizing the stomach of humans worldwide. Infections with this bacterium can generate pathologies ranging from chronic gastritis and peptic ulceration to gastric cancer. The best characterized H. pylori virulence factors that cause direct cell damage include an effector protein encoded by the cytotoxin-associated gene A (CagA), a type IV secretion system (T4SS) encoded in the cag-pathogenicity island (cag PAI), vacuolating cytotoxin A (VacA), γ-glutamyl transpeptidase (GGT), high temperature requirement A (HtrA, a serine proteas…

Reserpine attenuates biofilm formation and virulence of Staphylococcus aureus.

This study investigated the effects of reserpine, the main bioactive compound of Rauwolfia serpentina, on biofilm formation and biofilm-associated virulence factors production in a Gram-positive pathogen, Staphylococcus aureus. Crystal violet assay, MTT assay, Congo red binding, CLSM studies were performed to assess the antibiofilm activity. Molecular docking was performed to explain the possible mode of action, catheter model was used to evaluate its application potential and the combinatorial study was performed in search of an improved therapeutic formulation. Reserpine affected biofilm for…

Zika and Flavivirus Shell Disorder: Virulence and Fetal Morbidity.

Zika virus (ZIKV) was first discovered in 1947 in Africa. Since then, sporadic ZIKV infections of humans have been reported in Africa and Asia. For a long time, this virus was mostly unnoticed due to its mild symptoms and low fatality rates. However, during the 2015-2016 epidemic in Central and South America, when millions of people were infected, it was discovered that ZIKV causes microcephaly in the babies of mothers infected during pregnancy. An examination of the M and C proteins of the ZIKV shell using the disorder predictor PONDR VLXT revealed that the M protein contains relatively high

Programmed Delay of a Virulence Circuit Promotes Salmonella Pathogenicity.

Signal transduction systems dictate various cellular behaviors in response to environmental changes. To operate cellular programs appropriately, organisms have sophisticated regulatory factors to optimize the signal response. The PhoP/PhoQ master virulence regulatory system of the intracellular pathogen Salmonella enterica is activated inside acidic macrophage phagosomes. Here we report that Salmonella delays the activation of this system inside macrophages using an inhibitory protein, EIIANtr (a component of the nitrogen-metabolic phosphotransferase system). We establish that EIIANtr directly…

Differential virulence of camel Trypanosoma evansi isolates in mice.

This study assessed the virulence of Trypanosoma evansi, the causative agent of camel trypanosomiasis (surra), affecting mainly camels among other hosts in Africa, Asia and South America, with high mortality and morbidity. Using Swiss white mice, we assessed virulence of 17 T. evansi isolates collected from surra endemic countries. We determined parasitaemia, live body weight, packed cell volume (PCV) and survivorship in mice, for a period of 60 days' post infection. Based on survivorship, the 17 isolates were classified into three virulence categories; low (31-60 days), moderate (11-30 days) …

Basis of Virulence in Enterotoxin-Mediated Staphylococcal Food Poisoning.

The Staphylococcus aureus enterotoxins are a superfamily of secreted virulence factors that share structural and functional similarities and possess potent superantigenic activity causing disruptions in adaptive immunity. The enterotoxins can be separated into two groups; the classical (SEA-SEE) and the newer (SEG-SElY and counting) enterotoxin groups. Many members from both these groups contribute to the pathogenesis of several serious human diseases, including toxic shock syndrome, pneumonia, and sepsis-related infections. Additionally, many members demonstrate emetic activity and are freque…

A Precise Temperature-Responsive Bistable Switch Controlling Yersinia Virulence.

Different biomolecules have been identified in bacterial pathogens that sense changes in temperature and trigger expression of virulence programs upon host entry. However, the dynamics and quantitative outcome of this response in individual cells of a population, and how this influences pathogenicity are unknown. Here, we address these questions using a thermosensing virulence regulator of an intestinal pathogen (RovA of Yersinia pseudotuberculosis) as a model. We reveal that this regulator is part of a novel thermoresponsive bistable switch, which leads to high- and low-invasive subpopulation…