Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 20 for “"Viral diversity"”.
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Viral diversity and host-virus interactions in the model crenarchaeon Sulfolobus islandicus
… natural populations. Our understanding of viral impact on host physiology however, is based on a few model systems that represent a small fraction of the life-history strategies employed by hosts or viruses across the three domains of life. The factors that define these host-virus …
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Population Structure of Yellow Fever Virus: Influence of Viral Diversity on Vaccine Attenuation
… methods revealed the vaccine to be of lower diversity than the parental strain, leading to subsequent hypotheses that the level of complexity in the vaccine populations would be related to phenotypic stabilities. A deep sequencing study was performed comparing a set of rare 17D vaccine seeds, …
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Integrative Analysis of the Human Gut Phageome Using a Metagenomics Approach
… the gut ecosystem. However, the extent of viral diversity, biology, and worldwide epidemiology of gut phages remain largely unknown. In this thesis, I carry out a comprehensive genomic analysis of gut phages by harnessing the biggest collection of phage genomes, gut bacteria isolates, and …
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Mechanisms Controlling Virulence Thresholds of Mixed Viral Populations and Identification of Novel Host Barriers to Poliovirus Neuropathogenesis
… infections. This suggests the presence of viral and host barriers limiting disease. Here we examined viral barriers by exploring the concept of virulence thresholds using mixtures of virulent and attenuated viruses in a transgenic mouse model of poliovirus infection. We determined that …
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Evolution of viral populations in individuals infected with single and multiple HIV subtypes : a study of HIV-1 dual infection in a high risk cohort of female bar workers from Tanzania
… by high replication rate and high levels of diversity resulting in numerous quasispecies that form a 'swarm' in the infected individual. HIV diversification is driven by selection pressure exerted by the host. The role of high viral diversity in disease progression in context of infection …
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Evolution of antiviral breadth in Mx GTPases
As obligate parasites, viral pathogens coopt host resources and subvert cellular processes to promote their own replication. In response, host organisms have evolved numerous countermeasures to thwart viral infection. However, the molecular basis for how host antiviral defenses overcome the …
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Viral metagenomics and phylogenomics for One Health
… to reveal much more of the entire picture of viral diversity and evolution that by simply using them in a separated way. I show that this is the case for each one of the scientific questions addressed in this work, which are organised in three main chapters: - In the second chapter I analysed …
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The spread of Nipah and chikungunya viruses: implications for control
… primarily been derived from only two existing viral strains, raising questions as to what the unobserved spread and diversity of the virus might be in bat populations at different spatial scales. Using the most comprehensive genome set to date, I reconstructed a time-resolved phylogeny of Nipah …
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Exploring the ecology of Orthobunyaviruses in Virginia and their pathogenesis in murine and poultry models
… the last chapter, I explore the distribution and diversity of mosquitoes and arthropod-borne viruses in Virginia. Overall, these studies provide insight into CVV pathogenesis and in utero transmission, the role of domestic poultry in the maintenance and amplification of CVV, and lastly, evidence …
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Neutralising antibody responses in acute hepatitis C and SARS-CoV-2 infection
… antibodies (nAbs) are capable of blocking viral entry to host cells. Understanding the nAb response in early infection informs preventative and therapeutic interventions. The acute phase of hepatitis C virus (HCV) infection is characterised by two bottlenecks of viral diversity, one at the …
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Unraveling the Eco-Evolutionary Complexity of Uncultivated Bacteriophages in the Biosphere
… 1 provides a literature review on jumbo phage diversity, associated fitness tradeoffs of largeness, and predictions on which environments or ecological conditions may be enriched in jumbo phages. Chapter 2 assesses the evolutionary context giving rise to complex phages, by examining a group of …
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Metagenomic Analyses of the Human Gut Virome
… for human health. My thesis focused on the viral component of the microbiota that had been less characterized than its bacterial component. I first developed and applied a series of experimental and computational tools for metagenomic analyses of viruses purified from frozen fecal samples …
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Virologic Factors Contributing to the Genetic Diversification of Influenza Viruses Circulating in North American Swine
… mechanisms restrict reassortment in particular viral genotypes. This can further be applied to predict the likelihood that other viruses may reassort or be restricted from reassorting. Based on epidemiologic data not all viruses have the same ability to reassort, thus giving some viruses …
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Testing for host adaptive evolution using the maize streak virus model
… Given that these processes can sometimes promote viral diversity and result in the rapid evolution of new, fitter MSV variants, continuous genomic surveillance of MSV is therefore important. Based on analyses of full genome sequences, MSV-A has been classified into five subtypes (-A1, -A2, -A3, …
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Understanding the molecular and host determinants of Powassan virus pathogenesis across cellular and animal models
… neurotropism. While prior studies have examined viral diversity arising from single nucleotide polymorphisms, little is known about POWV recombination, defective RNAs (D-RNAs), or functional structural variants (SVs). Understanding POWV recombination in its natural vector could offer important …
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IDENTIFICATION AND CHARACTERISATION OF POTENTIALLY NOVEL HERPESVIRUSES IN VERTEBRATE SPECIES
… which incorporates glycoproteins that facilitate viral attachment and entry into host cells. Herpesviruses have co-evolved with specific hosts and are extremely adapted to them; indeed, in these adapted hosts they establish a life-long latent and sub-clinical infection. However, various …
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Human immunodeficiency virus type 1 diversity in patients initiating treatment in Northern South Africa
… carried out to determine when to start antiretroviral therapy (ART) have been showing that early ART initiation results in better health outcomes which are primarily indicated by suppressed viral loads and increase in CD4+ cell counts to healthy human ranges. This in turn is expected to reduce …
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Studies on severe acute respiratory syndrome coronavirus type -2 in Northern South Africa
… the evolutionary patterns and distribution of viral types at the population level can be comprehensively characterized. This study systematically reviewed literature published prior to the SARS-CoV-2 outbreak to investigate the prevalence and molecular epidemiology of HCoVs circulating in …
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Molecular characterization of faecal RNA virome of healthy chickens using next-generation sequencing
Submitted in complete fulfilment of the requirements for the degree of Master of Applied Science in Biotechnology, Durban University of Technology, Durban, South Africa, 2023.
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Indentification and molecular characterization of human papillomavirus infection among women living with and without HIV in selected health facilities in Limpopo Province, South Africa
… for most cases of CC. Due to the high genetic diversity of HPV, it is important to study the virus in different geographic locations, people, and in persons living with HIV, to inform the selection of genes for vaccine improvements and potential vaccine trial sites. Consequently, it is …