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The effect of amoeba predation on the evolution of virulence in human pathogenic microorganisms
Drncová, Eliška ; Šuťák, Róbert (advisor) ; Konupková, Anežka (referee)
Amoebae act as one of the main regulators of microbial communities, where, as a result of their predation, selection pressure is exerted for the emergence of defence mechanisms to achieve resistance. This adaptation allows microorganisms to randomly infect the human body and successfully defend against components of innate immunity, especially macrophages, which, like amoebae, are phagocytic cells. The manifestation of virulence in opportunistic pathogens is due to conserved macrophage pathways used for degradation of ingested material, which the microorganism has already encountered in amoebae. Because of this similarity, amoebae can be used to investigate the interaction between a pathogen and its host, which includes research on the virulence mechanisms of many human microbial infections. Among the most extensively studied organisms whose pathogenicity results from long-term interaction with amoebae are the bacterium Legionella pneumophila and the microscopic fungus Cryptococcus neoformans, with very different virulence strategies and manifestations. Understanding the evolutionary context and the advantages that microorganisms gain during interaction with amoebae informs us about the origins of virulence of opportunistic human pathogens.
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Functional and pathological changes in the stomach of hosts infected with gastric cryptosporidia
MARKOVÁ, Marie
The aim of this study was to observe and record the effect of infection with gastric species of the genus Cryptosporidium on the gastric characteristics of their hosts. The species Cryptosporidium proliferans was used for a series of experimental infections, and three types of model hosts - BALB/c mice, C57Bl6 mice and multimammate mice (Mastomys coucha) - were used as experimental animals. Oocysts were detected in the faeces of infected animals by standard parasitological, specific staining and molecular methods and the course of infection and pathogenicity of the Cryptosporidium species were described. Groups of animals comprising of 1-3 animals were humanely euthanized at seven-day intervals up to 70 days after infection. C. proliferans was found to have a direct effect on pH change in selected host types, with an increase in pH at the peak of infection and, depending on the host type, either an increase until the end of the experiment or, in the case of self-healing, a gradual return to physiological values. Pathological changes of the gastric mucosa during the course of the infection were recorded by histological methods, which were its thickening and increased mucus production, as well as the presence of inflammatory infiltrates and the intensity of the infection, to varying degrees across the selected hosts and the course of the infection. We found that even with short-term infection in BALB/c and C57Bl6 mice, there is both mucosal enlargement and thickening, although the pathological changes in these types of mice are not as extensive as in multimammate mice, which do not self-heal.
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Reakce imunitního systému na spirochéty Lymské boreliózy v závislosti na jejich patogenním potenciálu
ŠMÍDOVÁ, Hana
An infectious disease known as Lyme borreliosis is caused by the bacterium Borrelia, which is transmitted to humans by ticks. The bachelor thesis deals with the comparison of the pathogenic potential of three species of bacteria from the Borrelia burgdorferi sensu lato complex, which are characterized by their antigenic equipment. Differences between these species result in different responses of the host immune system and also affect tissue specificity, it determines the target area in the body where a given bacterium persists and causes symptoms typical of its species.
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Influence of sigle nucleotide mutations on influenza pathogenicity
Nitkulincová, Lucie ; Drda Morávková, Alena (advisor) ; Král, Jiří (referee)
Influenza virus caused several times the global concerns about the emergence of pandemics, in recent years. The most serious problem, in the fight against this virus, is its ability to quickly change its unusually antigenic specificity by reassortment and point mutations, especially in surface glycoproteins - haemagglutinin and neuraminidase. In this thesis I focused on point mutations in the hemagglutinin of influenza virus causing change in binding preference, which enables both influenza virus transmission between different hosts and unlimited proliferation in their tissues. The permanent change in amino acid sequence and thus the surface of hemagglutinin also largely prevents the host's immune system to destroy the virus efficiently and quickly enough to recognize when another infection. Each of the haemagglutinin subtypes has a different amino acid positions affecting its binding preference. Their summary is included in this thesis. Key words: influenza, single nucleotide mutations, pandemia, patoghenicity, hemagglutinin
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Role of exosomes and ectosomes in Trichomonas vaginalis virulence
Göblová, Rebeka ; Tachezy, Jan (advisor) ; Ditrich, Oleg (referee)
Trichomonas vaginalis is a causative agent of the most common non-viral sexually transmitted disease with approximately 275 mil new cases annually. Virulence of this parasitic depends on at least four factors: cell shape transformation, cytoadherence, secretion of cysteine proteases, and presence of endosymbionts. Over the past decades, extracellular vesicles appeared being another important player in the host-parasite interaction. It was discovered that T. vaginalis is one of the protists that can shed the extracellular vesicles such as exosomes and ectosomes. These vesicles are possibly involved in host-parasite communications, however limited information is available about their function. To investigate a possible role of exosomes in T. vaginalis virulence, we first selected suitable strain, which is free of endosymbionts (TV 17-2MI). Next we prepared six clones of TV 17-2MI strain to test whether the strain is homogenous concerning the virulence, or there are differences in virulence among individual cells. Mouse intraperitoneal virulence tests revealed that the clones displayed significant differences in virulence level, particularly in abscess formation and mortality of infected animals. Thus, for the first time we demonstrated heterogeneity of cells derived from a single T. vaginalis strain...
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Testování náchylnosti českých proveniencí jehličnatých dřevin vůči patogenní houbě Fusarium circinatum v laboratorních podmínkách
Lukačevičová, Aneta
Pine pitch canker (PPC), which is caused by Fusarium circinatum, is considered to belong among the most important destructive diseases affecting coniferous tree species in many locations throughout the world. In Europe, F. circinatum is currently present in Spain and Portugal, posing a high risk of its spread into currently disease-free countries in Europe. In the present study, the susceptibility of Pinus sylvestris, Picea abies, and Larix decidua originating in the Czech Republic to F. circinatum was tested. Furthermore, the presence of asymptomatic yet infected seedlings was also checked.
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Influence of sigle nucleotide mutations on influenza pathogenicity
Nitkulincová, Lucie ; Drda Morávková, Alena (advisor) ; Král, Jiří (referee)
Influenza virus caused several times the global concerns about the emergence of pandemics, in recent years. The most serious problem, in the fight against this virus, is its ability to quickly change its unusually antigenic specificity by reassortment and point mutations, especially in surface glycoproteins - haemagglutinin and neuraminidase. In this thesis I focused on point mutations in the hemagglutinin of influenza virus causing change in binding preference, which enables both influenza virus transmission between different hosts and unlimited proliferation in their tissues. The permanent change in amino acid sequence and thus the surface of hemagglutinin also largely prevents the host's immune system to destroy the virus efficiently and quickly enough to recognize when another infection. Each of the haemagglutinin subtypes has a different amino acid positions affecting its binding preference. Their summary is included in this thesis. Key words: influenza, single nucleotide mutations, pandemia, patoghenicity, hemagglutinin
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Laparotomické infekce hostitelů střevními a žaludečními kryptosporidiemi
HAVRDOVÁ, Nikola
Cryptosporidium are protozoan parasites that infect the gastrointestinal epithelium of various vertebrate hosts. The genus has two major phylogenetic groups: a gastric group that infect the epithelium of the stomach and an intestinal group that infect the epithelium of the small and large intestine. Cryptosporidium are transmitted by the faecal-oral route and infect epithelial cells following excystation of the environmental oocyst stage. It has been proposed that excystation of intestinal species is triggered by exposure to the acidic stomach contents, although this has not been verified experimentally. This study aimed to determine whether exposure to stomach contents is necessary for in vivo infection by the intestinal species C. parvum and whether passage through the intestine is necessary for the gastric species C. proliferans to cause infection. It was shown that purified and non-purified oocysts of C. parvum were infectious for SCID mice following surgical inoculation directly into different parts of the small intestine, demonstrating that passage through the stomach is not necessary for infection by this intestinal species. Inoculation of the jejunum resulted in a course of infection similar to oral inoculation. Cryptosporidium proliferans was infectious for na?ve SCID mice following surgical extraction from the stomach of infected SCID mice, demonstrating that passage through the small intestine is not necessary for infection by this gastric species. However, surgical inoculation of C. proliferans oocysts directly into the intestinum tenue did not cause infection.
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