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Funkční a patologické změny žaludku hostitelů reinfikovaných různými druhy a genotypy žaludečních kryptosporidií
MARKOVÁ, Marie
Representatives of the genus Cryptosporidium are intracellular parasites from the phylum Apicomplexa that parasitise the gastrointestinal tract of vertebrates. Within the genus, the species are divided into two groups depending on the site of infection: intestinal and gastric cryptosporidia. Infection with intestinal species is associated with watery diarrhoea, while infection with gastric species is usually asymptomatic. However, studies have indicated histopathological changes in gastric tissue during infection with these species. This work focuses on the influence of infection and reinfection with Cryptosporidium proliferans and Cryptosporidium muris CAT21 on gastric pH, morphological and pathological changes of the gastric mucosa in experimental mastomys and the mouse strains BALB/c and C57Bl6. In mice infected with C. muris CAT21, an increase in stomach pH was observed only after the primary infection; during reinfection, no increase in pH was observed on any of the days observed. In both groups, an increase in mucosal thickness was observed during infection, but was not as pronounced in BALB/c mice during reinfection as during primary infection. In C57Bl6 mice, reinfection resulted in a slight thickening, but no significant peak was observed and mucosal thickness remained similar. Inflammatory infiltrates were present in the tissue of both BALB/c and C57Bl6 mice during both infection and reinfection. Reinfection with C. proliferans led to an increase in gastric pH in both BALB/c and C57Bl6 mice. Although morphological changes were observed after reinfection, they were less pronounced. The results indicate that reinfection can influence the immune response and gastric morphology, but does not cause significant changes in pH. In addition, the influence of acidic water administration on the course of C. proliferans infection was investigated. No significant differences in the course of infection and pathological changes were observed between groups of mastomys supplied with acidic and tap water and infected with C. proliferans.
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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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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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Diversity, phylogeny and biology of various strains of Cryptosporidium muris
HAVRDOVÁ, Nikola
The morphological, biological, and molecular characteristics of various isolates of Cryptosporidium muris, namely HZ206 and TS03 were described. Oocysts of C. muris TS03 measuring 7.77 ? 0.23 × 5.20 ? 0.08 ?m with a length to width ratio of 1.48 ? 0.02 (n = 100) were morphometrically larger than C. muris HZ206 oocysts measuring 7.62 ? 0.40 × 6.63 ? 0.09 ?m; 1.32 ? 0.02 (n = 100) (p=0.034). Oocysts of both C. muris TS03 and HZ206 isolates obtained from naturally infected Tachyoryctes splendens and Mus musculus musculus, respectively, were infectious for na?ve 8-week-old Mastomys coucha. While the prepatent period of C. muris TS03 was 19-21 days post infection (DPI) and the animals did not lost infection within 120 DPI, animals infected with HZ206 start to shed oocysts 13-15 DPI with patent period 63-112 DPI. The accumulated value of infection intensity (AUC) in TS03 infected animals ranged from 250,000,000 to 800,000,000 oocysts per patent period (OPP) and HZ206 from 11,000,000 to 35,000,000 OPP. Histologically, a massive infection of cryptosporidia was detected in the glandular epithelium of stomach. Histopathological changes had a non-inflammatory character and included distinctive dilatation of infected parts of the glands with atrophy and metaplasia of the glandular epithelial cells. Infection with TS03 influenced the size of the stomach. While physiological weight of stomach of na?ve 12-week old mastomys and those infected with HZ206 were 0.61 ? 0.06 g and 0.70 ? 0.17 g,respectively, abnormal enlargement of stomach was observed in animals infected with TS03 (3.23 ? 0.51 g). There was no effect on feed intake among tested groups. Phylogenetic analyses based on small subunit rRNA, actin, MS1, MS2, MS3 and MS16 gene sequences revealed that C. muris TS03 is genetically distinct from other C. muris isolates. In conclusion, morphological, genetic, and biological data support the establishment of Cryptosporidium muris TS03 as a new species.
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Infectivity of \kur{Cryptosporidium andersoni} for different species of rodents
ONDRÁČKOVÁ, Zuzana
The infectivity and pathogenicity of Cryptosporidium andersoni (bovine isolate) for neonatal and adult southern multimammate mice (Mastomys coucha) and differently groups of gerbils was studied using transmission experiments. Cryptosporidium andersoni isolate used in this study was not infective for BALB/c mice, but experimental infection proved susceptibility of neonatal and adult M. coucha, neonatal and adult M. unguiculatus, adult Meriones tristrami, Seeketamys calurus, Gerbillus gerbillus to the infection. No signs of clinical illness or macroscopic findings were detected in infected animals. Adult G. gerbillus were the most susceptible to C. andersoni infection. These animals seem to be a useful laboratory model for study of C. andersoni infection.
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