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Regulatory mechanisms governing the virulence of the human pathogen Bordetella pertussis
Hejnarová, Václava ; Večerek, Branislav (advisor) ; Jurnečka, David (referee)
Bordetella pertussis is human pathogen, which causes severe respiratory disease called per- tussis or whooping cough. Pathogenicity of B. pertussis is mediated by a wide variety of vi- rulence factors including pertussis toxin, adenylate cyclase toxin, pertactin and filamentous haemagglutinin. Successful infection and colonization of the host depend on the precise timing of virulence factors production. For this purpose bacteria developed miscellaneous mechanisms of gene regulation. Two-component phosphotransferase systems, such as BvgAS, RisAK and PlrSR are involved in response to external stimuli. These systems of signal transduction modu- late bacterial gene expression profiles and establish consecutive phases of infection. Non-coding RNAs, particularly sRNAs and RNA chaperone Hfq provide additional level of regulation. Hfq is a post-transcriptional regulator, which mediates interaction of sRNA with target mRNA and thereby modulates their translation. Hfq affects approximately 10% of all B. pertussis genes including virulence factors such as type III secretion system, adenylate cyclase toxin, pertussis toxin and filamentous haemagglutinin. Knowledge of these regulatory mechanisms plays a key role in understanding of the pathogenesis of whooping cough and can lead to improved control over the spread...
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Virulence factors of the Trichophyton benhamiae complex
Machová, Lenka ; Čmoková, Adéla (advisor) ; Labuda, Roman (referee)
Dermatophytes are a group of fungi, some of which can cause skin diseases in humans and animals due to their ability to degrade keratinized tissue. Representatives of this group also include strains from the Trichophyton benhamiae complex, known to cause dermatophytosis especially of small rodents and rabbits. In the last decade, one of four populations of this complex has spread epidemically across Europe among guinea pigs and their breeders. To answer the question what stands behind the successful spread of this population, the gene expression and production of volatile organic compounds of epidemic and non-epidemic populations of T. benhamiae was investigated. Gene expression of three strains from each population was studied during growth in liquid medium and on ex vivo mouse skin models prepared according to a newly optimized protocol. RNAseq and RT-qPCR methods were chosen for the gene expression analysis. Based on the literature and the results of RNAseq preliminary analysis, several genes were selected for which specific primers were designed. The spectra of the produced volatile organic compounds of the same strains growing on sheep wool in vials were analyzed by GC-MS. While non-epidemic populations did not differ in gene expression and production of volatile organic compounds, the...
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Mechanism of action of bacterial toxins elevating the cAMP in host cells
Lepesheva, Anna ; Mašín, Jiří (advisor) ; Petráčková, Denisa (referee)
Cyclic adenosine monophosphate (cAMP) is an universal second messenger that regulates a large number of molecular mechanisms inside the eukaryotic cell. The level of synthesized cAMP is tightly regulated by endogenous adenylatecyclase (AC), and therefore this enzyme is often a target for various bacterial toxins. To manipulate intracellular cAMP levels in a target cell, bacteria have developed two different strategies for their toxins. Bordetella pertussis adenylate cyclase toxin (CyaA), Bacillus anthracis edema factor (EF) and Pseudomonas aeruginosa exotoxinY have in their structure an enzymatic AC domain which is activated by an intracellular cofactor and has several times higher activity than the eukaryotic AC enzyme itself. Other toxins, such as Bordetella pertussis pertussis toxin (PT), Vibrio cholerae cholera toxin (CT), and Escherichia coli heat labile toxin use ADP-ribosylation reaction of AC-coupled heterotrimeric G proteins to increase its activity and uncontrolled cAMP production. This work presents a literature search with accent on the molecular mechanism of interaction of these toxins with the target cell. Keywords: bacterial pathogens, virulence factors, intracellular cAMP elevation, bacterial toxins, adenylatecyclase (adenylylcyclase), Bordetella pertussis, Vibrio cholerae,...
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Cryptococcus neoformans virulence factors
Bauer, Martin ; Kuthan, Martin (advisor) ; Abrhámová, Kateřina (referee)
Cryptococcus neoformans is an opportunistic pathogenic yeast causing around 600 000 deaths annually. Its ability to cause a chronic infection is given by multiple virulence factors, which include the ability to grow in high temperature, polysaccharide capsule, oxidative stress tolerance and the expression of surface proteins. Unusual and resistant titan cells, which develop through the process of titanization, and the process of phenotypic switching can also be included. Despite intensive research, these virulence factors are yet to be fully described. Inducing factors of titan cells and participating signalling pathways are known. However, a complete model of titanization does not yet exist. So far, the mechanism of phenotypic switching is also unknown. In this work the current knowledge of virulence factors of C. neoformans is presented and summarised.
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Analysis of protein cargo of extracellualr vesicles isolated from the yeast Candida albicans
Hlubučková, Lucie ; Konečná, Klára (advisor) ; Janďourek, Ondřej (referee)
Charles University Faculty of Pharmacy in Hradec Králové Study program: Pharmacy Candidate: Lucie Hlubučková Consultant: RNDr. Klára Konečná, Ph.D. Title of thesis: Analysis of protein cargo of extracellular vesicles isolated from the yeast Candida albicans Backgroung: The aim of this diploma thesis was to analyze the protein cargo carried in extracellular vesicles released from the yeast Candida albicans (C. albicans), which is one of the most important mycotic agens. Extracellular vesicles (EVs) are utilized as "transport vehicles", for the delivery of effector molecules into extracellular milieu. These molecules and primarilly proteins can play different roles in host-pathogen interactions. Proteins isolated from EVs and identified by proteomic approach were sorted into categories according to their molecular function and localization for the purpose of finding out, which proteins are predominantly distributed via extracellular vesicles into extracellular space after induction of nutrition starvation. Analysis of EVs protein cargo with focus on virulence factors could extend the knowledge about extracellular vesicles and their potential role in pathogenesis. Methods: Chosen C. albicans yeast strain was a clinical isolate strain isolated from a premenopausal women suffering from recurrent...
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The detection of factors virulence and resistance genes bacterial pathogens in patients with cystic fibrosis
Jandová, Oldřiška ; Melter, Oto (advisor) ; Nyč, Otakar (referee)
Cystic fibrosis is an autosomal recessive genetic disorder, which is caused by mutation in CFTR gene (Cystic Fibrosis Transmembrane Conductance Regulator). This gene encodes protein with the same name, which is responsible for pathogenesis of CF. Cystic fibrosis is characteristic for frequent infection of respiratory system, which causes, destruction of lung tissue. These infections are characterized by occurrence of typical bacterial pathogenes, for example: S. aureus, P. aeruginosa etc. S. aureus is one of the most typical opportunistic pathogens, which causes serious difficulties in patients with the cystic fibrosis. Strains of S. aureus are characterized by production of multiple virulence factors and resistance to broad spectrum of antibiotics. Besides common mechanisms of resistance there is also possibility of emergence of so called Small Colony Variants in chronically infected patients. These resistant subpopulation is relatively common among S. aureus isolates of patients with CF. The aim of this work was to study isolates from three patients with cystic fibrosis, who are chronically infected by S. aureus. Our goal was to determine changes in the pattern of the antibiotic resistance and occurrence of virulence factors together with description of SCV strains. Powered by TCPDF (www.tcpdf.org)
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Virulence factors of Bordetella pertussis
Držmíšek, Jakub ; Večerek, Branislav (advisor) ; Vopálenská, Irena (referee)
Bordetella pertusis is a Gram-negative, aerobic, non-spore-forming coccobacillus. Although it's strictly human pathogen, it's possible to infect other mammals at laboratory conditions. Transmission among hosts is mediated via respiratory tract droplets. Infection could be direct, host to host, alternatively by contaminated environment. Bordetella colonizes upper respiratory tract, wherefrom descends into lungs and causes disease known as whooping cough or pertussis leading to 195 000 deaths of 16 mil. incidences per year (according to WHO report from 2010). More than twenty years before, respectively to found pertussis toxin, that time intensively under examination, pertussis was marked as toxin-mediated disease. In the course of time, more other virulence factors were revealed, that could be divided into groups of adhesins, toxins and others. Adhesins are filamentous haemagglutinin, pertactin and fimbriae. Toxins include pertussis toxin, adenylate cyclase, tracheal cytotoxin, dermonecrotic toxin and lipopolysaccharide. Most of virulence factors are regulated by two component system Bvg. However, it is needed lots of other factors for successful infection as for example autotransporters or so called siderophores serving as iron acquisition from environment. Secretion of virulence factors is mediated by its...
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