Siga este link para ver outros tipos de publicações sobre o tema: Host-virus relationships.
Teses / dissertações sobre o tema "Host-virus relationships"
Crie uma referência precisa em APA, MLA, Chicago, Harvard, e outros estilos
Veja os 45 melhores trabalhos (teses / dissertações) para estudos sobre o assunto "Host-virus relationships".
Ao lado de cada fonte na lista de referências, há um botão "Adicionar à bibliografia". Clique e geraremos automaticamente a citação bibliográfica do trabalho escolhido no estilo de citação de que você precisa: APA, MLA, Harvard, Chicago, Vancouver, etc.
Você também pode baixar o texto completo da publicação científica em formato .pdf e ler o resumo do trabalho online se estiver presente nos metadados.
Veja as teses / dissertações das mais diversas áreas científicas e compile uma bibliografia correta.
1
Wang, Pui, e 王培. "Study of the host factors interacting with H5N1 influenza virus". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43085210.
Texto completo da fonte
2
Wang, Pui. "Study of the host factors interacting with H5N1 influenza virus". Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B43085210.
Texto completo da fonte
3
Baldridge, Gerald Don. "Molecular biology of Bunyavirus-host interactions". Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184934.
Texto completo da fonteResumo:
Ribonuclease T1 oligonucleotide fingerprint (ONF) analysis was used to study genomic stability of La Crosse virus (Bunyaviridae) during vertical and horizontal transmission in the laboratory. No RNA genomic changes were detected in vertebrate cell culture-propagated virus isolated (following oral ingestion and replication) from the natural mosquito host, Aedes triseriatus. Genomic changes were not detected during transovarial passage of virus through two generations of mosquitoes or in virus isolated from suckling mice infected by transovarially infected mosquitoes. These results demonstrate that the La Crosse virus genome can remain relatively stable during transovarial transmission (TOT) in the insect host and during transfer between insect and vertebrate hosts. ONF analysis was used to demonstrate TOT of reassortant California serogroup bunyaviruses in Aedes treiseriatus. Mosquitoes were simultaneously inoculated with temperature sensitive mutants of La Crosse and Snowshoe hare viruses able to replicate at 33°C but not at 40°C. Putative reassortants, selected by replication at 40°C, were isolated from progeny mosquitoes and mice infected by these mosquitoes. ONF analysis confirmed that they were reassortants. Approximately 75% of the M segment and 25% of the L segment nucleotide sequences of Inkoo virus (Bunyaviridae) were determined by Sanger dideoxynucleotide sequencing of cDNA clones. Comparison of the M segment nucleotide and deduced amino acid sequences with those of four other bunyaviruses, representing two serogroups, revealed greater conservation of nucleotide than of amino acid sequence between serogroups. Areas of the sequences representing nonstructural protein(s) were less conserved than glycoprotein regions. The L segment nucleotide sequence begins with the known 3' end of the viral L segment and contains an open reading frame encoding the amino terminal 505 amino acids of the viral L protein. The amino acid sequence contains the glycine-aspartate-aspartate motif which is conserved in many RNA-dependent RNA polymerases. Comparison of the L segment sequences with those in the GEN Bank Data Base revealed no significant similarities with any other sequence.
4
Burgess, Shane Campbell. "Investigations into host cell-virus relationships and tumour immunity in Marek's disease". Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324271.
Texto completo da fonte
5
Crill, Wayne Douglass. "Experimental evolution and molecular basis of host-specific viral adaptation /". Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
Texto completo da fonte
6
Hadi, Buyung Asmara Ratna Flanders Kathy L. Bowen Kira L. "Aphid vectors and grass hosts of barley yellow dwarf virus and cereal yellow dwarf virus in Alabama and western Florida". Auburn, Ala., 2009. http://hdl.handle.net/10415/2018.
Texto completo da fonte
7
Li, Tin-wai Olive. "Influenza polymerase subunit compatibility between human H1 and H5 viruses". Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B41896890.
Texto completo da fonte
8
Brown, J. K., e M. R. Nelson. "Transmission, Host Range and Virus-Vector Relationships of Chino del Tomate Virus (CdTV), a New Whitefly-transmitted Geminivirus of Tomato". College of Agriculture, University of Arizona (Tucson, AZ), 1988. http://hdl.handle.net/10150/214160.
Texto completo da fonteResumo:
The transmission properties, host range, and virus- vector relationships of chino del tomate virus (CdTV), a new whitefly-transmitted geminivirus of tomato, are described. The virus is transmitted by B. tabaci, the sweet potato whitefly, but not by seed or sap. The virus infects members of the Asclepiadaceae, Leguminosae, Malvaceae, and Solanaceae. In virus-vector studies, minimum AAF and IAF times were 1 hour and 2 hours, respectively. The virus was retained by its whitefly vector for 4.5 and 7.3 days following 24- and 72-hr AAF respectively. Relative efficiencies of transmission for 1, 5, 10 and 20 B. tabaci were 15, 49, 84 and 100 percent, respectively. The chino del tomate (CdT), or leaf curl disease of tomato (Lycopersicon esculentum Mill.), was first reported in cultivated tomato fields in Sinaloa, Mexico in 1970-71 (4). Presently, it occurs in tomato production areas of the west coast of Sinaloa and may affect 100 percent of the plants in a field (1). The disease is characterized by curled and rolled leaves, thickened veins, a bright-to-subdued-yellow mosaic which varies with time of the year, stunting, and a reduced fruit set (1,3). Recently, a whitefly -transmitted geminivirus, CdT virus (CdTV), was implicated as the causal agent of the disease (1,3), but information concerning the biological nature of the virus is lacking. Here, we present the results of studies involving virus transmission, experimental host range, and virus -vector relationships.
9
Maekawa, Akiko Medical Sciences Faculty of Medicine UNSW. "Characterisation of the immune co-receptor function of CD4". Publisher:University of New South Wales. Medical Sciences, 2007. http://handle.unsw.edu.au/1959.4/40498.
Texto completo da fonteResumo:
CD4 is a co-receptor for binding of T cells to antigen-presenting cells (APC) and the primary receptor for human immunodeficiency virus-I. The disulfide bond in the second extracellular domain (D2) of CD4 is reduced on the cell surface, which leads to formation of disulfide-linked homodimers. A large conformational change must take place in D2 to allow for formation of the disulfide-linked dimer. Domain swapping of D2 is the most likely candidate for the conformational change leading to formation of two disulfide-bonds between Cysl30 in one monomer and Cysl59 in the other one (Cys133 and Cysl62 in the mouse CD4). Thus, we hypothesized that the domain swapping of D2 in CD4 regulates its co-receptor function of antigenspecific T cell activation. We found that mild reduction of the extracellular part of human CD4 resulted in formation of disulfide-linked dimers. We then tested the functional significance of dimer formation for co-receptor function using the engineered Jurkat T cell system by expressing wild-type or disulfide-bond mutant mouse CD4. Eliminating the D2 disulfide bond markedly impaired CD4's coreceptor function as assessed by antigen-specific IL-2 production. Exogenous wild type thioredoxin, but not redox-inactive thioredoxin, could inhibit the CD4-mediated IL-2 production, suggesting that the redox state of D2 disulfide bond is controlled by this oxidoreductase. Furthermore, structural modeling of the complex ofthe T cell receptor and domain-swapped CD4 dimer bound to class II major histocompatibility complex and antigen supports the domain-swapped dimer as the immune co-receptor. The known involvement of D4 residues Lys318 and Gln344 in dimer formation isalso accommodated by this model. These findings imply that disulfide-linked dimeric CD4 is the preferred functional co-receptor for binding to APC. Strategies to promote dimerisation of CD4 should, therefore, enhance the immune response, while inhibiting dimer formation is predicted to be immunosuppressive.
10
Knez, Jozo Capone John P. "Characterization of the role of herpes simplex virus protein VP16 in viral gene expression through interactions with the virion host shutoff protein (VHS) and HCF-1/". *McMaster only, 2003.
Encontre o texto completo da fonte
11
Li, Tin-wai Olive, e 李天慧. "Influenza polymerase subunit compatibility between human H1 and H5 viruses". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B41896890.
Texto completo da fonte
12
Boyd, Ann Marie. "Interactions between common vertebrate hosts and the mosquito vectors of Ross River and Barmah Forest viruses in urban Brisbane, South East Queensland, Australia /". [St. Lucia, Qld.], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18059.pdf.
Texto completo da fonte
13
Walter, Cheryl Tracy. "Establishing experimental systems for studying the replication biology of Providence virus". Thesis, Rhodes University, 2009. http://hdl.handle.net/10962/d1003987.
Texto completo da fonteResumo:
Providence virus (PrV) is a member of the Tetraviridae, a family of small, positive sense, single-stranded RNA viruses, which characteristically infect the midgut tissue of heliothine larvae. PrV is the only known tetravirus that replicates in cultured insect cells. The virus comprises a monopartite genome resembling members of the genus Betatetravirus with the capsid precursor protein undergoing autoproteolytic cleavage at its C-terminus consistent with other tetravirus capsid precursor proteins. Analysis of viral cDNA predicted the presence of three potential overlapping gene products (from 5` to 3`): (1) p130, a protein of unrecognized nucleotide or amino acid homology with a 2A-like processing site at its N-terminus; (2) p104, the replicase ORF, which was found to be phylogenetically related to tombus-and umbraviruses replicases. The presence of a read-through stop signal in the p104 ORF was proposed to produce and amino terminal product with a predicted MW of 40 kDa (p40) and (3) the capsid protein precursor (81 kDa) which has two 2A-like processing sites at its N-terminus. Metabolic radiolabelling of viral translation products in persistently infected MG8 cells and in vitro translation of the individual ORFs were performed in order to analyse the expression of PrV gene products. p130 was translated with no evidence of 2A-like processing. Two products of 40 kDa and 104 kDa were translated from the p104 ORF, indicating that the read-through stop signal was likely to be functional. Finally, the capsid protein precursor ORF produced a major translation product of 68 kDa corresponding to the capsid protein precursor as well a peptide of 15 kDa that was attributed to the activity of the second 2A-like site at the N-terminus of the p81 ORF. The subcellular distribution of viral RNA (vRNA) and p40 in MG8 cells was investigated using immunofluorescence and biochemical fractionation. The results showed that p40/p104 and vRNA accumulated in polarized, punctate structures in some but not all MG8 cells and in some cases, co-localization was observed. This thesis concludes that PrV is a novel tetravirus with significant similarities plant carmolike viruses that should be re-classified at the family level.
14
Wu, Jing Qin. "Microarray studies of HIV-host interactions in relation to disease status and therapy effects". Thesis, The University of Sydney, 2008. https://hdl.handle.net/2123/28129.
Texto completo da fonteResumo:
HIV-host interactions can be interrogated at the level of both protein (proteome) and
RNA (transcriptome). At protein level, previous studies have shown that expression
levels of cell surface antigens such as CD38 and HLA-DR are related to HIV disease
status as well as the efficacy of highly active antiretroviral therapy (HAART). To
date, the immunophenotyping of cell surface antigens relies on flow cytometry,
allowing estimation of 3-6 markers at a time. The recently described DotScan
antibody microarray technology enables the simultaneous analysis of a large number
of cell surface antigens, providing new opportunities to study virus—host interactions
by identifying cumulative expression patterns of cell surface antigens that could
differentiate HIV disease status and HAART responses. While DotScan antibody
microarray focuses on a subset of proteins of human proteome which may have
direct diagnostic/prognostic values, DNA microarray Illumina Sentrix Human-6
Expression BeadChip can profile the whole human genome (>48,000 transcripts),
offering systematic insights into the mechanisms underlying virus-host interactions.
The overall objective of this study is to investigate the HIV-host interactions using
these newly developed microarray technologies. The objective of the first part is to
use antibody microarray to identify (1) the fingerprints of the cell surface antigen
expressions on both CD4+ and CD8+ T cells that distinguish different HIV disease
groups and (2) the cell surface antigens on peripheral blood mononuclear cells
(PBMCs) which are differentially expressed over time between sustained and
transient responders of HAART. The objective of the second part is to use the
Illumina Sentrix Human-6 Expression BeadChip to (1) identify the transcriptional
signatures of CD8+ T cells from the long-term non-progressor (LTNP) group and the
viremic patient (VIR) group and (2) investigate the impact of a transient viremic
surge on the CD8+ T cell transcriptome from an LTNP.
15
Kauffman, Anne Kathryn Marie. "Demographics of lytic viral infection of coastal ocean vibrio". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90046.
Texto completo da fonteResumo:
Thesis: Ph. D., Joint Program in Biological Oceanography (Massachusetts Institute of Technology, Department of Civil and Environmental Engineering; and the Woods Hole Oceanographic Institution), 2014.Cataloged from PDF version of thesis.
Includes bibliographical references.
Viral predation on bacteria in the ocean liberates carbon from the particulate fraction, where it is accessible to higher trophic levels, and redirects it to the dissolved fraction, where it supports microbial growth. Although viruses are highly abundant in the ocean little is known about how their interactions with bacteria are structured. This challenge arises because the diversity of both bacteria and viruses is exceedingly high and interactions between them are mediated by specific molecular interactions. This thesis uses heterotrophic bacteria of the genus Vibrio as a model to quantify virus-host interactions in light of host population structure and ecology. The methods developed in this thesis include streamlining of standard bacteriophage protocols, such as the agar overlay, and facilitate higher throughput in the isolation and characterization of novel environmental virus-host systems. Here, >1300 newly isolated Vibrio are assayed for infection by viral predators and susceptibility is found to be common, though total concentrations of predators are highly skewed, with most present at low abundance. The largest phylogenetically-resolved host range cross test available to date is conducted, using 260 viruses and 277 bacterial strains, and highly-specific viruses are found to be prevalent, with nearly half infecting only a single host in the panel. Observations of blocks of multiple viruses with nearly identical infection profiles infecting sets of highly-similar hosts suggest that increases in abundance of particular lineages of bacteria may be important in supporting the replication of highly specific viruses. The identification of highly similar virus genomes deriving from different sampling time points also suggests that interactions for some groups of viruses and hosts may be stable and persisting. Genome sequencing reveals that members of the largest broad host-range viral group recovered in the collection have sequence homology to non-tailed viruses, which have been shown to be dominant in the surface oceans but are underrepresented in culture collections. By integrating host population structure with sequencing of over 250 viral genomes it is found that viral groups are genomically cohesive and that closely-related and co-occurring populations of bacteria are subject to distinct regimes of viral predation.
by Anne Kathryn Marie Kauffman.
Ph. D.
16
Saayman, Michael John. "The establishment of a routine monitoring technique for detecting the most prevalent pathogenic viruses in river water, Western Cape, South Africa". Thesis, Cape Peninsula University of Technology, 2012. http://hdl.handle.net/20.500.11838/1497.
Texto completo da fonteResumo:
Thesis submitted in fulfilment of the requirements for the degree
Master of Technology: Biomedical Technology
in the Faculty of Health and Wellness Sciences
at the Cape Peninsula University of Technology, 2012In many developed countries worldwide the provision of safe, clean water is an expected commodity. In South Africa however, as in most developing countries, the access and supply of water safe for human consumption is challenged or complicated by pollution and more recently water availability. Point-source pollutants in surface- and groundwater are normally the most concentrated closest to the pollutant source (such as the end of a pipe or an underground injection system). Examples of point-source pollution are commercial and industrial businesses, that often discharge waste such as solvents and heavy metals from their operations. In contrast, non-point-source pollution occurs due to runoff moving across or through the ground and absorbing and accumulating pollutants which eventually end up in streams, rivers and dams. The lack of waste removal and adequate sanitation facilities results in the disposal of faecal matter and sewage into storm water drains which flow directly into the river systems contributing to the incidence of diseases such as gastroenteritis, diarrhoea and chronic lung ailments, caused by waterborne pathogenic bacteria, viruses and fungi. Routine water quality analysis however, does not include monitoring for viral contaminants, as this process is hampered by the lack of simple, reliable, time- and cost-effective testing methods to concentrate and detect viral pathogens. The primary aim of this study was thus to establish and optimise routine monitoring techniques for the detection of rota-, adeno- and enteroviruses in the Berg- and Plankenburg Rivers, Western Cape. Initially, various concentration and extraction methods were compared for the optimum recovery of viruses from spiked water samples. One hundred milliliter water samples were spiked with one milliliter rotavirus and two milliliters adenovirus control virions (Coris Bioconcept, Gembloux, Belgium). Optimisation testing of enterovirus was however, not completed due to the unavailability of a positive control. Four viral concentration techniques, namely the Silicon dioxide (SiO2) method, positively charged, negatively charged and the mixed-ester filters, were compared. Various nucleic acid extraction methods were also employed to establish which method would provide optimum yields for both DNA and RNA nucleic acids. The extraction techniques included the TRIzol method (Invitrogen, California, USA) for RNA extraction, the Roche High Pure PCR Template Preparation kit (Roche, Mannheim, Germany) for DNA extraction, and the QIAamp Ultrasens Virus kit (Qiagen GmbH, Hilden, Germany) for simultaneous RNA and DNA extraction. The use of virus specific primers within the PCR technique was also optimised. In addition, gene specific primers and oligo(dT)15 primers were tested and compared to establish which primers would yield the best results since gene specific primers are said to be more sensitive than oligo(dT)15 primers (van Pelt-Verkuil et al., 2008) when synthesising cDNA (rotavirus). The SiO2 concentration method yielded variable results when it was used with the various nucleic acid extraction techniques in this study, since positive PCR results were obtained when used in combination III with some techniques, while negative results were obtained with others. Similarly, variable results were also obtained when negatively charged filters were used to concentrate virus particles, and when this method was used in conjunction with various virus nucleic acid extraction techniques to identify different viruses by RT-PCR and PCR. Results for the non-charged mixed-ester filter were comparable to the positively charged filters when used in conjunction with the various nucleic acid extraction techniques in this study. Both these techniques yielded the highest viral particle concentration from the spiked water samples. Pilot study results indicated the presence of rotavirus and adenovirus detected by RT-PCR and PCR respectively, when filtering through the positively charged filter. The positively charged filter/QIAamp UltraSens virus kit combination was found to be the optimum combination when analysing the spiked water results and was then employed for the concentration of virus particles in the river water samples collected from the Plankenburg- and Berg River systems throughout the study period. The expected PCR product of 346 bp for rotavirus was absent in all 72 river water samples analysed for both river systems. In contrast to the PCR results obtained for rotavirus, the expected product of 261 bp for adenovirus was detected in 22 (30.5%) samples collected throughout the study period. Fifteen of the 22 adenovirus positive samples were found in the Plankenburg River (distributed over all sites), while seven of the 22 adenovirus positive samples were found in the Berg River (all sites). A nested PCR was used to detect enterovirus in the river water samples collected from both river systems throughout the study period. In the first round of the enterovirus PCR 15 river water samples (at various sites for both river systems) yielded a faint 513 bp product. Further amplification by nested PCR then yielded 13 (18.1%) positive nested PCR products of 297 bp. The incidence of adenovirus and enterovirus in river waters reported in the current study and the Van Heerden et al. (2003) investigation motivates for similar studies to be conducted in drinking water, dam water used for recreational purposes as well as rainwater, which is gaining popularity as a sustainable water source.
17
Maluta, Nathalie Kristine Prado. "Respostas biológicas e comportamentais de Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae) a plantas de tomate infectadas com Tomato chlorosis virus (ToCV) e Tomato severe rugose virus (ToSRV) e atividades estiletares associadas à inoc". Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/11/11146/tde-09082017-100910/.
Texto completo da fonteResumo:
Vários fitovírus são capazes de influenciar o comportamento e desenvolvimento biológico de seus insetos vetores de modo a favorecer sua disseminação entre plantas hospedeiras, mas pouco se sabe a respeito dos efeitos de infecções virais sobre moscas-brancas Bemisia tabaci (Genn.), uma vez que se trata de um complexo de espécies, que transmite vírus de diferentes gêneros com distintos modos de transmissão. Considerando-se a importância de B. tabaci como praga e vetora e o grande prejuízo causado a diversos cultivos devido à transmissão de fitovírus, o presente trabalho teve como objetivos: a) Investigar a preferência para pouso e o comportamento arrestante de B. tabaci MEAM 1 (Middle East-Asia Minor 1) em plantas de tomate não infectadas e infectadas com o crinivírus Tomato chlorosis virus (ToCV) transmitido de modo semipersistente, e o begomovírus persistente-circulativo, Tomato severe rugose virus (ToSRV); b) Avaliar os efeitos diretos e indiretos de ToCV sobre o desempenho biológico de B. tabaci MEAM 1 c) Comparar o comportamento alimentar de adultos não-virulíferos de B. tabaci MEAM 1 em plantas de tomate não infectadas e infectadas com ToCV ou ToSRV, utilizando-se a técnica de Electrical Penetration Graph (EPG); d) Correlacionar as atividades estiletares de B. tabaci MED (Mediterranean) com a inoculação de ToCV em tomateiro. Verificou-se que plantas infectadas com ToCV não exercem atração sobre B. tabaci MEAM 1; há efeito direto quando o inseto está virulífero; no entanto, este efeito não parece favorecer a disseminação de ToCV. Já ToSRV exerce efeito direto que favorece sua disseminação, pois insetos virulíferos são mais atraídos por plantas não infectadas. A mosca-branca exibe comportamento arrestante em plantas de tomate sadias, e tende a deixar plantas infectadas com ToCV ou ToSRV, sugerindo que tais vírus reduzem a qualidade nutricional da planta hospedeira. Em relação ao desenvolvimento biológico do inseto, observou-se efeito direto de ToCV apenas de alongamento da duração do primeiro ínstar ninfal, e efeito indireto negativo sobre a viabilidade da fase ninfal, pois apenas 32% das ninfas eclodidas chegaram à fase adulta em plantas infectadas, contrastando com 77% em plantas não infectadas. Nos ensaios de EPG, verificou-se que a infecção de plantas de tomate por ToCV ou ToSRV não influenciou o comportamento alimentar do vetor de modo a favorecer a transmissão desses vírus, pois afetou apenas parâmetros não relacionados às atividades floemáticas. A transmissão de ToCV está principalmente associada à salivação nos elementos de floema (forma de onda E1) (52,2% de plantas infectadas), mas pode ocorrer com baixa frequência antes de E1 (3,5%). Entretanto, há maior eficiência de transmissão quando os indivíduos realizam vários episódios de E1+E2 (ingestão de seiva nos vasos do floema). Os dados obtidos na presente tese ajudam a esclarecer um pouco mais as complexas relações entre B. tabaci e diferentes fitovírus, e como as respostas comportamentais podem variar em função do modo de transmissão.Several phytoviruses are capable of influencing the behavior and biological development of their insect vectors in order to promote their spread among host plants, but information about the effects of viral infections on whiteflies Bemisia tabaci (Genn.) is not available, since it is a species complex, which transmits vírus belonging to different genus with distinct transmission modes. Considering B. tabaci importance as a pest and a vector and the great damage caused to several crops due to the transmission of phytovirus, the present work had as objectives: a) To investigate the preference for landing and the arrestant behavior of B. tabaci MEAM 1 (Middle East-Asia Minor 1) in non-infected and infected tomato plants with semi-persistent crinivirus, Tomato chlorosis virus (ToCV) and the persistent-circulative begomovirus, Tomato severe rugose virus (ToSRV); b) To evaluate the direct and indirect effects of ToCV on the biological performance of B. tabaci MEAM 1 c) To compare the feeding behavior of non-viruliferous B. tabaci MEAM 1 in non-infected and ToCV or ToSRV-infected tomato plants using the Electrical Penetration Graph (EPG) technique; d) Correlate the stylets activities of B. tabaci MED (Mediterranean) with the inoculation of ToCV in tomato. It has been found that ToCV-infected plants do not exert an attraction on B. tabaci MEAM 1; there is a direct effect when the insect is viruliferous, however, this effect does not seem to favor the spread of ToCV. ToSRV has a direct effect that favors its dissemination, as viruliferous insects are more attracted to non-infected plants. The whitefly exhibits an arrestment behavior on non-infected plants, and tends to leave plants infected by ToCV or ToSRV, suggesting that such viruses reduce the nutritional quality of the host plant. In relation to the biological development, we observed a direct effect of ToCV only on the first ninfal instar, and a negative indirect effect on nymphal viability, since only 32% of the initial individuals reached adulthood in ToCV-infected plants contrasting with 77% in non-infected plants. In the EPG tests, it was verified that the infection of tomato plants by ToCV or ToSRV did not influence the feeding behavior of the vector in order to favor the transmission of these viruses, since it affected only parameters not related to the phloem. The transmission of ToCV is mainly associated to salivation in the phloem elements (waveform E1) (52,2% of infected plants), but may occur in a low proportion before E1 (3,5%). However, there is a greater efficiency of transmission when individuals perform several episodes of E1 + E2 (phloem sieve elements). The data obtained in this thesis help to clarify a little more about the complex relationships between B.tabaci and different phytovirus, and how the behavioral responses may vary depending on the mode of transmission.
18
Haugen, Samuel Arthur McGrath. "Assessing Cereal Aphid Diversity and Barley Yellow Dwarf Risk In Hard Red Spring Wheat and Durum". Thesis, North Dakota State University, 2018. https://hdl.handle.net/10365/28791.
Texto completo da fonteResumo:
Barley yellow dwarf (BYD), caused by Barley yellow dwarf virus and Cereal yellow dwarf virus, and is a yield limiting disease of small grains. A research study was initiated in 2015 to identify the implications of BYD on small grain crops of North Dakota. A survey of 187 small grain fields was conducted in 2015 and 2016 to assess cereal aphid diversity; cereal aphids identified included, Rhopalosiphum padi, Schizaphis graminum, and Sitobion avenae. A second survey observed and documented field absence or occurrence of cereal aphids and their incidence. Results indicated prevalence and incidence differed among respective growth stages and a higher presence of cereal aphids throughout the Northwest part of North Dakota than previously thought. Field and greenhouse screenings were conducted to identify hard red spring wheat and durum responses to BYD. Infested treatments in the greenhouse had significantly lower number of spikes, dry shoot mass and yield.
19
James, Samantha. "Herpèsvirus de primates et de chauves-souris du nouveau monde : modèles d'étude des relations évolutives hôtes-virus DNA polymerase sequences of New World Monkey Cytomegaloviruses : another molecular marker with which to infer Platyrrhini systematics Novel herpesviruses of neotropical bats and their relationships with other members of the Herpesviridae family". Thesis, Guyane, 2019. http://www.theses.fr/2019YANE0004.
Texto completo da fonteResumo:
Les virus appartenant à la famille Herpesviridae (ordre Herpesvirales) sont répartis au sein de trois sous-familles : Alpha-, Beta- et Gamma-herpesvirinae. Ils ont été identifiés à partir d’un large spectre d’espèces hôtes, allant des mammifères aux reptiles en passant par les oiseaux et ont la capacité de persister toute au long de la vie de l’hôte. La plupart de ces virus sont par ailleurs spécifiques d’une espèce hôte. La large distribution des herpèsvirus, associée à une infection généralement asymptomatique chez l’hôte naturel suggèrent que ces virus auraient co-évolué avec leurs hôtes.Mon premier axe de travail a porté sur l’identification de cytomégalovirus (CMV) chez les primates non-humains du Nouveau Monde (PNHNM) afin de voir si la diversification de ces virus suivait celle de leurs hôtes. De fait, une étude préalable conduite sur les primates de l’Ancien Monde avait démontré que les CMV les infectant présentaient un fort signal de co-divergence avec leurs hôtes. Or, parmi les différentes espèces de primates testées, seules quelques-unes provenaient du Nouveau Monde. Afin de répondre à cette question, nous avons effectué un criblage moléculaire de 244 échantillons d'ADN sanguin provenant de 20 espèces d'Amérique centrale et du sud. Par une approche de PCR utilisant des amorces consensus dégénérées ciblant des motifs hautement conservés du gène de l'ADN polymérase des herpèsvirus, nous avons caractérisé de nouvelles séquences virales de sept genres représentatifs des trois familles de PNHNM. Ces résultats démontrent ainsi que la plupart des espèces de PNHNM peuvent être infectées par un virus appartenant au genre Cytomegalovirus. Par ailleurs, les analyses phylogénétiques effectuées, couplées à la datation moléculaire des séquences obtenues, soutiennent cette hypothèse co-évolutive.Mon second axe visait à identifier des herpèsvirus de chauves-souris du Nouveau Monde afin d’en étudier la distribution et la diversité. La recherche d’herpèsvirus chez les chauves-souris est plus récente. Elle a bénéficié de l’intérêt porté à ces mammifères au début des années 2000 du fait de leur rôle de réservoirs de virus potentiellement zoonotiques. C’est à partir de 2007 que les premières séquences d’herpèsvirus de chauves-souris ont été décrites. Il s’en est suivi la description de dizaines de nouvelles séquences identifiées de différentes espèces d’Afrique, d’Asie, d’Océanie, d’Europe et d’Amérique. Néanmoins, la distribution des espèces testées était géographiquement inégale et seules quelques-unes provenaient du Nouveau Monde. Nous avons effectué un criblage moléculaire de 195 échantillons d’ADN sanguin provenant de 11 espèces appartenant à trois familles (Phyllostomidae, Mormoopidae et Molossidae). En utilisant la même approche que celle appliquée au PNHNM, nous avons obtenu des séquences virales (ADN polymérase et/ou Glycoprotéine B) de toutes les espèces testées. Celles-ci se répartissent au sein des sous familles Beta- et Gamma-herpesvirinae. Quatorze séquences partielles du gène de l'ADN polymérase, correspondant à trois beta- et onze gamma-herpèsvirus, ont été identifiées. Douze séquences partielles du gène de la glycoprotéine B, toutes de gamma-herpèsvirus, ont été caractérisées. Chaque séquence était spécifique à une espèce de chauve-souris et, chez certaines espèces, de multiples virus ont été identifiés. Les analyses phylogénétiques de ces séquences ont permis d'identifier des clades spécifiques aux virus de chauve-souris. Ceux composés de séquences obtenues à partir de différentes espèces appartenant à des sous-familles distinctes suivent la taxonomie des chauves-souris. Cette étude confirme l'étonnante diversité des herpèsvirus de chauve-souris et élargit nos connaissances sur leur spectre d'hôtesViruses belonging to the Herpesviridae family (order Herpesvirales) are enveloped double-stranded DNA viruses distributed into three subfamilies: Alpha-, Beta- and Gamma-herpesvirinae. These viruses have been identified from a wide range of host species, ranging from mammals to reptiles to birds. They have the ability to persist throughout the life of the host in a latent form and to reactivate. Most of these viruses are specific to a host. The wide distribution of herpesviruses, generally associated with an asymptomatic infection in their natural host, suggests that these viruses have co-evolved with their hosts.The first part of this work was dedicated to the identification of cytomegaloviruses (CMV, genus Cytomegalovirus) in New World non-human primates (NWNHP) to see if the diversification of these viruses followed that of their hosts. A previous study on Old World primates had demonstrated that CMVs infecting them showed a strong signal of co-divergence with their hosts. Nevertheless, among the different species of primates tested, only a few were from the New World. To test this hypothesis, we performed a molecular screening of 244 blood DNA samples from 20 Central and South American species. Through a PCR approach using degenerate consensus primers targeting highly conserved motifs of the DNA polymerase gene of herpesviruses, we characterized new viral sequences from 12 species belonging to seven representative genera of the three families of NWNHP. These results demonstrate that most species of NWNHP can be infected with a virus belonging to the Cytomegalovirus genus. In addition, phylogenetic analyzes of the obtained sequences combined with their molecular dating support a co-evolutionary scenario. This study led us to propose that CMVs sequences of NWNHP could serve as a molecular marker with which to infer the not yet fully resolved systematics of these primates.The second part of this work was on identifying herpesviruses from New World bats to study their distribution and diversity. The search for herpesviruses in bats is more recent. In the early 2000s it benefited from studies dedicated to other viral families given their role as reservoirs of potentially zoonotic viruses. The first description of bat herpesvirus sequences dated back from 2007. Over the past decade, dozens of herpesvirus sequences have been described from different bat species on every continent. Nevertheless, the distribution of the tested species was geographically uneven and only a few were from the New World. Molecular screening of 195 blood DNA samples from 11 species belonging to three families (Phyllostomidae, Mormoopidae and Molossidae) was performed. Using the same approach as applied to NWNHP, we obtained viral sequences (DNA polymerase and/or glycoprotein B) from all tested species. These are distributed within the Beta- and Gamma-herpesvirinae subfamilies. Fourteen partial sequences of the DNA polymerase gene, corresponding to three beta- and eleven gamma-herpesviruses, have been identified. Twelve partial sequences of the glycoprotein B gene, all gamma-herpesviruses, have been characterized. Each sequence was specific to a bat species and in some species multiple viruses were identified. Phylogenetic analyzes of these sequences have identified clades specific to bat viruses. Those composed of sequences obtained from different species belonging to distinct subfamilies follow the taxonomy of bats. This study confirms the astonishing diversity of bat herpesviruses and broadens our knowledge on their host spectrum.This work is the largest conducted to date in terms of species diversity of non-human primates and bats from the Neotropical realm. Nevertheless, the samples tested represent only a tiny part of this diversity. Further analyzes, on a broader panel of representative species from other geographic areas will increase our understanding of the evolutionary history of these viruses
20
Xing, Li. "Non-enveloped virus infection probed with host cellular molecules : a structural study /". Stockholm, 2002. http://diss.kib.ki.se/2002/91-7349-289-2.
Texto completo da fonte
21
Teo, Chong Gee. "Analysis of the Epstein-Barr virus-host relationship by in situ hybridisation". Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47684.
Texto completo da fonte
22
Berard, Alicia. "Global quantitative host proteomic assay of infected cells highlight virus specific protein changes and identify a novel role for secretogranin ii protein in virus infections". ACS Publications, 2012. http://hdl.handle.net/1993/30717.
Texto completo da fonteResumo:
Viruses are obligate parasites that use the host cellular machinery to produce progeny virions. The host responds to this invading pathogen by induction of the immune system; however, the virus employs a variety of strategies to overcome these attacks. The complexity of the virus-host interaction is of great interest to researchers with aims to both characterize the relationship and target steps of the viral life cycle to hinder infection. Many targeted tactics employ single protein analysis; however, approaches that examine the whole set of virus/host interactions are available. Transcriptional alterations within host cells have been determined for many virus- host interactions by micro-array techniques; however little is known about the effects on cellular proteins. This study uses a quantitative mass spectrometric-based method, SILAC, to study differences in a host cell's proteome with infection by a virus. Mammalian reoviruses and herpes simplex viruses are prototypical viruses commonly studied to determine virus life cycle and interactions with hosts. Using three strains of reoviruses and one HSV1 strain, cells were infected to identify differentially regulated proteins at different times. Thousands of proteins were identified for each virus type, some up or down regulated after infection. Biological functions and network analyses were performed using online networking tools. These pathway analyses indicated numerous processes including cell death and inflammatory response are affected by T1L reovirus infection. Comparing reovirus strains revealed a greater overall proteomic change in host function when infected with the more pathogenic T3DC strain. For the HSV infection, host proteins altered during the different immediate early, earlyand late phases of infection helped characterize the host-virus interaction parallel to the virus life cycle. Overall, my study has characterized proteomic changes in different virus infection systems, identifying numerous novel cellular functional pathways and specific proteins altered during virus infections, specifically the secretogranin II protein that had opposite types of regulation in reoviruses and HSV and was examined for its effects on virus replication. Further studies on the novel proteomic characteristics may provide greater understanding to the complex virus-host interactome, leading to possible antiviral targets.October 2015
23
Sassi, Giovanna. "Relative quantification of host gene expression and protein accumulation upon turnip mosaic potyvirus infection in tobacco". Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81433.
Texto completo da fonteResumo:
Turnip mosaic virus (TuMV) infects a variety of crops, worldwide, including the economically relevant Brassicacea family. It was previously demonstrated that TuMV infection in tobacco protoplasts leads to an overall decrease of host protein. However, it remains unclear whether this phenomenon is due to the repression of plant gene transcription during the infection period or due to viral inhibition of host translation. In this study, quantification of various transcripts and protein products from infected tobacco was performed via real-time RT-PCR and ELISA. In comparison to the gamma-tubulin endogenous control, gene expression for the tobacco H3, HSP70 and granule-bound starch synthase was affected by TuMV infection with time.Tobacco protein accumulation in whole leaf tissues was also significantly affected by increase of virus particles.
24
Messias, Ueliton. "Atividade da superoxido dismutase, catalase, peroxidases e acumulo de H2O2 associados a infecção de um Carlavirus em soja e um Potyvirus no feijoeiro". [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/315675.
Texto completo da fonteResumo:
Orientador:Jorge VegaTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-12T04:10:59Z (GMT). No. of bitstreams: 1 Messias_Ueliton_D.pdf: 899792 bytes, checksum: c79dd05dd46e901a7add3fa66d7afc3f (MD5) Previous issue date: 2008
Resumo: As plantas defendem-se continuamente contra ataques de bactérias, vírus, fungos, invertebrados e de outras plantas. O estresse oxidativo é um tipo de resposta fisiológica da planta após o reconhecimento do patógeno, podendo resultar em sintomas nas plantas dependendo da sensibilidade do hospedeiro, e também relacionada à mecanismos de defesa. Foram analisadas plantas de soja cultivares BRS132 (muito sensível) e IAC17 (pouco sensível) infectadas pelo Cowpea mild mottle virus (CPMMV) e plantas de feijoeiro cultivar BT2 infectado pelo Cowpea aphid-borne virus (CABMV). O trabalho teve como objetivos avaliar a concentração de peróxido de hidrogênio, analisar a resposta antioxidante das plantas à infecção viral quanto às variações na atividade da superóxido dismutase, catalase, ascorbato peroxidase, guaiacol peroxidase e siringaldazina peroxidase e verificar as localizações dos vírus e das peroxidases em diferentes tecidos das plantas. O CPMMV induziu uma doença aguda, com sintomas severos e culminando com a morte da planta de soja 'BRS132'. Na soja 'IAC17', o vírus induziu uma doença crônica com mosaico leve a partir da segunda folha trifoliolada. As concentrações de peróxido de hidrogênio e as atividades da catalase, ascorbato peroxidase, guaiacol peroxidase e siringaldazina peroxidase foram maiores nas plantas infectadas, tanto na soja 'BRS132' como na soja 'IAC17', em relação às plantas sadias. O CPMMV foi localizado nos tecidos do pecíolo e do caule, na soja 'BRS132' nas regiões periféricas e medula, e na soja 'IAC17' principalmente nas regiões periféricas. No feijoeiro cultivar BT2, o CABMV induziu resposta aguda na primeira folha foram maiores nas plantas infectadas, exceto a atividade da superóxido dismutase, que apresentou valores similares nas plantas infectadas e nas sadias. O CABMV foi localizado nas regiões periféricas e medula dos tecidos do pecíolo, e no caule a invasão foi limitada à região periférica. As peroxidases e a siringaldazina peroxidase foram localizadas nas mesmas regiões do pecíolo onde foram detectados o CPMMV e o CABMV. No feijoeiro 'BT2', a infecção viral induziu uma resposta semelhante à observada na soja 'BRS132', com algumas diferenças relacionadas ao fato de que neste caso, a infecção pelo CABMV não resultou na morte da planta de feijoeiro. Também se observou aumento expressivo de atividade da siringaldazina peroxidase no 7º dia após inoculação, diferente da soja 'BRS132' em que este aumento ocorreu mais tarde. A invasão generalizada dos vírus no pecíolo foi semelhante em feijoeiro 'BT2' e soja 'BRS132', principalmente nos dias em que começou a ocorrer abscisão dos folíolos. Já a invasão do caule foi generalizada em soja 'BRS132' e limitada à região periférica em feijoeiro. Possivelmente, o aumento precoce de atividade da siringaldazina peroxidase em feijoeiro, já no 7º dia após inoculação, limitou a invasão do vírus aos tecidos periféricos do caule. Isto explicaria o fato de o feijoeiro 'BT2' não sofrer morte da gema apical e da planta. trifoliolada, apresentando sintomas de mosaico, maior rugosidade, lesões necróticas nas nervuras e folíolos ''fechados''. Nesta cultivar, todos os parâmetros avaliados.
Abstract: Plants defend themselves from attacks of bacteria, fungi, viruses, invertebrate and other plants. Oxidative stress is a kind of physiological response of the plant related to defense mechanisms after recognition the pathogen, which may result in disease symptoms depending on host sensitivity. In this work, plants of two varieties of soybean infected by Cowpea Mild Mottle Virus (CPMMV), one highly sensitive (BRS132) and other with low sensitivity (IAC17) to the virus, were analyzed. Also, responses of bean plants (cv. Black Turtle 2, BT2) to Cowpea Aphid-Borne Mosaic Virus (CABMV) were examined. The parameters assessed included peroxide content (as hydrogen peroxide, H2O2), and activity of the following enzymes: superoxide dismutase, catalase, ascorbate peroxidase, guayacol peroxidase and syringadazine peroxidase. Distribution of virus and peroxidases in different tissues was also examined. In soybean cv BRS132, CPPMV induced an acute disease with severe symptoms finally resulting in plant death. In the less sensitive soybean cv IAC17, CPMMV induced a chronic disease with mild mosaic which was only visible in the second trifoliate and later leaves. Peroxide content and activity of guayacol and syringaldazine peroxidases were higher in infected plants of both cultivars. The virus was immuno-localized in stem and petiole cross sections, appearing in peripheral tissues and pith in cv BRS132, whereas in cv IAC17 it was localized mainly in the peripheral portion. In bean cv BT2, CABMV induced a acute response in the first trifoliate leaf, which presented a rough mosaic, necrotic lesions in veins and a "wilted" aspect. In this species all the assessed parameters showed higher values in the infected plants. Only the activity of superoxide dismutase was similar in healthy and infected plants. The vírus was localized in the pith and peripheral tissues of bean petioles, and only in the peripheral region of stems. Peroxidase and syringaldazine peroxidase activities were localized in the same tissues of the petiole where the CPMMV was localized in soybean plants and CABMV in bean plants. The response to CABMV observed in bean cv BT2 was similar to the response of soybean BRS132 to CPMMV, with some differences, since in bean the virus infection did not induce plant death. A significant rise in syringadazine activity was detected seven days after inoculation (DAI) in beans, while in soybean this increase occurred one day later. Both species also showed similar pattern of invasion of petiole tissues by the virus, mainly at the moment of abscission of leaflets. However, the virus invasion of stem was generalized in soybean BRS132 and contrastingly, limited to the peripheral tissues in bean. One possibility is that the early increase in syringaldazine activity observed in bean 7 DAI is indicative of some type of restriction to the spread of the virus, limiting it to the stem peripheral tissues. Probably this restricted spread of the virus in the stem underlies the survival of the apical meristem in bean cv BT2 in contrast to the death of the meristem in soybean cv BRS132.
Doutorado
Doutor em Biologia Vegetal
25
Bojic, Teodora. "Host involvement in the replication of potato spindle tuber viroid and the evolutionary relationship between plant viroids and the hepatitis delta virus". Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28353.
Texto completo da fonteResumo:
The present study examines the interaction between host RNA polymerase II (RNAP II) and potato spindle tuber viroid (PSTVd), with the goal of locating and characterizing a putative RNAP II promoter within the viroid's RNA genome. By using a co-immunoprecipitation approach coupled with deletion and mutational analysis, RNAP II was shown to specifically bind the left terminal hairpin loop of PSTVd(+) RNA. The interaction with RNAP II appears to be dependent on PSTVd secondary structure features, rather than a particular sequence. These findings provide direct evidence of association between RNAP II and PSTVd RNA, and render a unique example of a possible RNA promoter for RNAP II.
The second part of the study examines the evolutionary relationship between viroids and the hepatitis delta virus (HDV), as these pathogens share key structural and functional characteristics. We conclude, based on infection experiments, that HDV and viroids share common strategies and host factors to fulfill their respective life-cycles. We found that both HDV and an HDV mutant lacking the HDAg protein-coding region (miniHDV) can replicate in a plant host. However, miniHDV and PSTVd can replicate in human cells only in the presence of the small delta antigen (HDAg-S). Together, these results provide support for the hypothesis that HDV evolved from a viroid-like element through the capture of a cellular transcript necessary for its adaptation to a human host.
26
Norton, Amanda Mary. "Disentangling the Relationship Between Deformed wing virus, the Honey Bee Host (Apis mellifera) and the Viral Vector, the Ectoparasitic Mite Varroa destructor". Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/25768.
Texto completo da fonteResumo:
The ectoparasitic mite Varroa destructor is indisputably the most significant driver of global colony losses of the Western honeybee, Apis mellifera. Colony deaths are frequently attributed to Deformed wing virus (DWV), which is vectored by the mite. In this thesis I attempt to disentangle the tripartite relationship between DWV,
A. mellifera and V. destructor, by investigating whether the two major DWV genotypes, A and B, differ from the point of view of the virus, the honey bee and the mite. First, I assessed the viral accumulation dynamics of multiple DWV genotypes during single or co-infection in Australian pupae (naïve to both DWV and Varroa). I found that DWV-B accumulated to higher levels than DWV-A when singly and co-injected, suggesting that DWV-B is able to outcompete DWV-A. Yet despite higher viral loads, DWV-B was associated with the lowest level of mortality. Therefore, I next investigated if the bees’ immune system reacted differently to the two DWV genotypes. I examined the expression of 19 immune genes and analysed the small RNA response of pupae exposed to DWV-A and DWV-B. Overall, I found little evidence to indicate that A. mellifera responds differently to either genotype. Finally, to uncover what role vector transmission by V. destructor plays in DWV genotype prevalence at the colony level, I experimentally increased and decreased the number of mites within A. mellifera colonies and analysed viral loads over a period of ten months. I found that DWV-A was strongly affected by mite numbers, whereas DWV-B persisted in the presence and absence of V. destructor. Overall, my thesis furthers our understanding of the intricate relationship between DWV, A. mellifera and V. destructor, and provides insight into some of the factors that may be contributing to the increasing prevalence of DWV-B.
27
Devignot, Stéphanie. "Le Syndrome de choc de dengue, approches clinique et in vitro". Thesis, Aix-Marseille 2, 2010. http://www.theses.fr/2010AIX20672/document.
Texto completo da fonteResumo:
Le syndrome de choc de dengue (DSS) est une complication potentiellement mortelle dela dengue, première arbovirose humaine et problème majeur de santé publiquemondial. Il survient chez une fraction des patients, et résulte d’une fuite plasmatiquemassive, non prédictible, dont la physiopathologie est mal connue. Le décryptage de laréponse de l’hôte est donc essentiel pour améliorer le pronostic et le traitement despatients. Ce travail de thèse a abordé les mécanismes de la fuite plasmatique du DSS dedeux façons : versant immunitaire et versant endothélial. D’une part, nous avons comparéen ex vivo les profils transcriptionnels sanguins de patients présentant différentes formescliniques de dengue, afin d’identifier des mécanismes contribuant à la survenue du DSS.Cette étude a révélé l’activation chez les patients en DSS, de signatures proinflammatoiresà l’interface entre immunité innée et métabolisme lipidique, représentantde nouveaux bio-marqueurs potentiels du DSS. D’autre part, les études in vitro desinteractions entre un virus de dengue et deux lignées de cellules endothélialesmicrovasculaires humaines (CEM), a révélé des différences d’intensité de réponseantivirale, ainsi que des différences dans l’expression de protéines impliquées dans laperméabilité, selon l’origine des territoires endothéliaux. Ces résultats suggèrent que levirus contribue directement au dysfonctionnement endothélial, au côté de mécanismesindirects médiés par des facteurs de l’hôte. Les deux types d’approches mises en oeuvreont ainsi établi de nouvelles données sur la physiopathologie du DSS, qui pourraient àterme trouver des applications dans la prise en charge des maladesDengue Shock Syndrome (DSS) is a life-threatening form of dengue infection, which is thefirst arboviral disease worldwide and a major public health problem. This severecomplication happens in a fraction of patients, and is the consequence of anunpredictable massive plasma leakage. The pathophysiology underlying DSS is stillunknown. Deciphering the host response to dengue infection is essential to improve boththe prognosis and the therapeutic management of dengue patients. This thesis workintended to study the mechanisms involved in DSS’ plasma leakage at both immunity (exvivo study) and endothelium (in vitro study) levels. First, in a ex vivo study, we comparedwhole blood cells’ transcriptional profiles of patients suffering from different clinicalpresentations of dengue disease, in order to identify mechanisms contributing to DSSoutcome. This study revealed the activation of pro-inflammatory signatures at theinterface of innate immunity and lipid metabolism, in DSS patients. Those signatures maybe new bio-markers of DSS. Second, in vitro studies of the consequences of a directinteraction between a dengue virus and human microvascular endothelial cells (MEC),revealed differences in antiviral response intensities and in the expression of proteinsinvolved in the endothelial permeability, depending on the endothelial origin of theMEC. Those results suggest that the virus directly contributes to the endotheliumdysfunction, together with indirect mechanisms triggered by soluble and cellular factors.Our investigations have produced new data on the pathophysiology of DSS that couldhave applications to the monitoring and treatment of the patients
28
Enchéry, François. "Étude de la modulation de la voie canonique d'activation de NF-kB par les protéines non structurales du virus Nipah". Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEN093/document.
Texto completo da fonteResumo:
Le virus Nipah (NiV) est un paramyxovirus zoonotique du genre Henipavirus, qui a émergé en 1998. NiV infecte l'homme et cause des troubles respiratoires et des encéphalites avec une forte létalité. A l’inverse, chez les hôtes naturels de NiV, les chauves-souris de la famille des Pteropodidae, l’infection est asymptomatique. Cependant, les mécanismes permettant aux Pteropodidae de contrôler l’infection sont inconnus à ce jour. NiV produit des protéines non structurales, V, W et C, qui sont des facteurs de virulence. V, W et C inhibent les voies de l’interféron de type 1. De plus, la protéine W inhibe la production de chimiokines in vitro et module la réponse inflammatoire in vivo, mais son mécanisme d’action reste inconnu. La voie NF-κB étant le principal régulateur de la réponse inflammatoire, nous avons émis l’hypothèse que W pourrait moduler la voie NF-κB. Nous avons démontré que la protéine W inhibe l'activation de la voie canonique de NF-κB induite par TNFα et IL-1β, effet pour lequel sa région C-terminale spécifique est nécessaire. Nous avons également identifié quels signaux d’import et d’export nucléaires de W sont nécessaires à son effet inhibiteur et ainsi mis en évidence l’importance du trafic nucléo-cytoplasmique de W pour l’inhibition de NF-κB. L’étude des interactions de W avec les protéines cellulaires nous a permis d’identifier un partenaire prometteur connu pour son rôle dans le rétrocontrôle négatif de NF-κB. Enfin, le rôle de W dans l'inhibition de la voie NF-κB a été démontré pendant l'infection par NiV. Les résultats obtenus ouvrent la voie à la compréhension du mécanisme par lequel W module la réponse inflammatoire. Finalement, afin de mieux comprendre le contrôle de l’infection de NiV par son hôte naturel, nous avons généré des lignées cellulaires primaires et immortalisées de chauve-souris Pteropus giganteus. Ces cellules devraient permettre de mieux comprendre les mécanismes par lesquels ces chauves-souris contrôlent l’infection viraleNipah virus (NiV), from Henipavirus genus, is a zoonotic paramyxovirus, which emerged in 1998. In humans, it causes acute respiratory distress and encephalitis with a high lethality. Conversely, the natural hosts of NiV, bats from the Pteropodidae family, are asymptomatic. The mechanisms by which the Pteropodidae control infection are unknown to date. NiV produces non-structural proteins, V, W and C, which are virulence factors. V, W and C inhibit the type 1 interferon pathways. Moreover, W inhibits the production of chemokines in vitro and modulates the inflammatory response in vivo, but its mechanism remains unknown. The NF-κB pathway being the main regulator of the inflammatory response, we hypothesized that W could modulate the NF-κB pathway. We demonstrated that protein W inhibits the activation of the NF-κB canonical pathway induced by TNFα and IL-1β. The specific C-terminal region of W is necessary for this effect. We have also identified which nuclear import and export signals of W are necessary for its inhibitory effect and thus highlight the importance of the nucleo-cytoplasmic trafficking of W for the inhibition of NF-κB. The study of the interactions of W with the cellular proteins allowed us to identify a promising partner known for its role in the negative feedback of NF-κB. Finally, the role of W in the inhibition of the NF-κB pathway was demonstrated during the infection with NiV. The results obtained open the way to understanding the mechanism by which W modulates the inflammatory response. Finally, to better understand the control of the infection of NiV by its natural host, we generated primary and immortalized cell lines of Pteropus giganteus bat. These cells should provide a better understanding of the mechanisms by which these bats control viral infection
29
Sikora, Dorota. "Hepatitis Delta Virus: Identification of Host Factors Involved in the Viral Life Cycle, and the Investigation of the Evolutionary Relationship Between HDV and Plant Viroids". Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/22910.
Texto completo da fonteResumo:
Hepatitis delta virus (HDV) is the smallest known human RNA pathogen. It requires the human hepatitis B virus (HBV) for virion production and transmission, and is hence closely associated with HBV in natural infections. HDV RNA encodes only two viral proteins - the small and the large delta antigens. Due to its limited coding capacity, HDV needs to exploit host factors to ensure its propagation. However, few human proteins are known to interact with the HDV RNA genome. The current study has identified several host proteins interacting with an HDV-derived RNA promoter by multiple approaches: mass spectrometry of a UV-crosslinked ribonucleoprotein complex, RNA affinity chromatography, and screening of a library of purified RNA-binding proteins. Co-immunoprecipitation, both in vitro and ex vivo, confirmed the interactions of eEF1A1, p54nrb, PSF, hnRNP-L, GAPDH and ASF/SF2 with both polarities of the HDV RNA genome. In vitro transcription assays suggested a possible involvement of eEF1A1, GAPDH and PSF in HDV replication. At least three of these proteins, eEF1A1, GAPDH and ASF/SF2, have also been shown to associate with potato spindle tuber viroid (PSTVd) RNA. Because HDV’s structure and mechanism of replication share many similarities with viroids, subviral helper-independent plant pathogens, I transfected human hepatocytes with RNA derived from PSTVd. Here, I show that PSTVd RNA can replicate in human hepatocytes. I further demonstrate that a mutant of HDV, lacking the delta antigen coding region (miniHDV), can also replicate in human cells. However, both PSTVd and miniHDV require the function of the small delta antigen for successful replication. Our discovery that HDV and PSTVd RNAs associate with similar RNA-processing pathways and translation machineries during their replication provides new insight into HDV biology and its evolution.
30
Leobold, Matthieu. "Démonstration fonctionnelle de la nature virale des particules sans ADN de la guêpe parasitoïde venturia canescens". Thesis, Tours, 2018. http://www.theses.fr/2018TOUR4017.
Texto completo da fonteResumo:
Chez la guêpe parasitoïde Venturia canescens, des particules virales dépourvues d'ADN appelées VLP (pour "Virus-like Particules") sont produites spécifiquement dans les ovaires et tapissent le chorion des oeufs qui sont injectés dans la chenille hôte. Les VLP ont une fonction immunosuppressive pour l'hôte parasité et permettent ainsi la survie des oeufs du parasitoïde. Ces VLP résultent de l’intégration d’un nudivirus dans le génome de l’ancêtre de la guêpe, nudivirus qui a été ensuite domestiqué pour former des liposomes viraux capables de véhiculer dans l’hôte des protéines de virulence d'origine cellulaire. L’étude réalisée au cours de cette thèse a eu pour objet, d’une part, d'étudier les mécanismes de domestication virale qui ont conduit au virus symbiotique endogène actuel nommé VcENV (pour V. canescens endogenous nudivirus) et d’autre part, d'apporter des éléments de réponse sur le processus de morphogénèse et le mode d'action parasitaire des VLPViral particles devoid of DNA called VLPs (for Virus-Like Particles) are specifically produced in the ovaries of the parasitoid wasp Venturia canescens and line the chorion of the wasp’s eggs injected into the host caterpillar. VLPs are immunosuppressive and allow parasitoid eggs survival. These VLPs result from the integration of a nudivirus into the wasp ancestor genome, nudivirus which was then domesticated to form viral liposomes capable of carrying, into the host, virulence proteins of cellular origin. The aim of the study carried out during this thesis was, first, to analyze the viral domestication mechanisms that led to the current endogenous symbiotic virus called VcENV (for V. canescens endogenous nudivirus) and secondly to provide some answers on VLPs morphogenesis process and parasitic mode of action
31
Oon, Aileen Biotechnology & Biomolecular Sciences Faculty of Science UNSW. "Molecular evolution of hepatitis C virus quasispecies". 2007. http://handle.unsw.edu.au/1959.4/40659.
Texto completo da fonteResumo:
The viral dynamics of the hepatitis C virus (HCV) in newly acquired infection are not well understood. HCV exists within an individual as a spectrum of minor variants termed quasispecies. The evolution of minor variants may contribute to viral escape of the host?s immune response, thereby facilitating development of chronic infection. The hypervariable 1 region (HVR1) is the most heterogeneous part of the HCV genome and contains a putative B-cell epitope. Thus, diversity in HVR1 could be a strategy used to evade neutralising antibodies. Acutely infected individuals (n=24) were examined with the aim of defining HVR1 quasispecies diversity in acute infection. The characterisation of the E1/HVR1 sequence and host specific evolution of HCV minor variants in treatment nonresponders was also investigated. HCV E1/HVR1 fragments were amplified from 48 sera using a combined reverse transcription-polymerase chain reaction (RT-PCR). Products were TA cloned into pCRIITOPO and approximately 10-20 clones were sequenced from each sample. HVR1 quasispecies diversity was examined longitudinally via sequence analysis. Quasispecies diversity was characterised primarily by mean nucleotide diversity. The mean HVR1 diversity of the acute cohort (n=48; 2.12% ?? 2.22) was lower than the diversity obtained for a cohort of chronically infected individuals (n=99; 4.5% ?? 5.1). There was no significant difference in mean HVR1 diversity between the HIV/HCV co-infected and HCV mono-infected groups (p=0.99) or between the clearer and non-clearer groups (p=0.85). Examination of amino acid usage and the hydropathic profile of each position in HVR1 revealed that sequence variation was confined to specific sites. The investigation of host specific evolution of HVR1 quasispecies demonstrated that minor variants (comprising 10- 20% of a population) became the dominant species over time in two treatment non-responders. These variants bore mutations that were not reflected in the consensus sequence of their respective populations at the initial timepoint analysed. Common infection was identified by 98% HVR1 sequence homology within two pairs of individuals. The evolution of common strains appeared to be different between individuals, suggesting host pressures may influence quasispecies evolution. This thesis provided an insight into the viral dynamics and host specific evolution of acute phase quasispecies.
32
"The early host responses upon HBV replication". Thesis, 2010. http://library.cuhk.edu.hk/record=b6074821.
Texto completo da fonteResumo:
Further functional investigation revealed that knockdown of GRP78 expression by RNA interference resulted in a significant increase of both intracellular and extracellular HBV virions in the transient HBV-producing HepG2 cells, concomitant with enhanced levels of hepatitis B surface antigen and e antigen in the culture medium Conversely, overexpression of GRP78 in HepG2 cells led to HBV suppression concomitant with induction of the positive regulatory circuit of GRP78 and interferon-beta 1 (IFN-beta1). In this connection, IFN-beta1-mediated 2', 5'-oligoadenylate synthetase (OAS) and ribonuclease L (RNase L) signaling pathway was noted to be activated in GRP78-overexpressing HepG2 cells. Moreover, GRP78 was significantly down-regulated in the livers of chronic hepatitis B patients after effective anti-HBV treatment (p= 0.019) as compared with their counterpart pre-treatment liver biopsies.Hepatitis B virus (HBV) infection is a global public health problem, which plays a crucial role in the pathogenesis of chronic hepatitis, cirrhosis and hepatocellular carcinoma. Although considerable progress has been made over the past decade, the pathogenesis of HBV infection and the mechanisms of host-virus interactions are still elusive.
In conclusion, the present study demonstrates for the first time that GRP78 functions as an endogenous anti-HBV factor via IFN-beta1-OAS-RNase L pathway in hepatocytes. Induction of hepatic GRP78 may provide a novel therapeutic approach in treating HBV infection.
In this study, we applied a two-dimensional gel electrophoresis and mass spectrometry-based comparative proteomic approach to globally analyze the host early response to HBV by using an inducible HBV-producing cell line HepAD38. Twenty-three proteins were identified as differentially expressed, with glucose-regulated protein 78 (GRP78) as one of the most significantly up-regulated proteins induced by HBV replication. This induction was further confirmed in both HepAD38 and HepG2 cells transfected with HBV-producing plasmids by real-time reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, as well as in HBV-infected human liver biopsies by immunohistochemistry.
Ma, Yan.
Adviser: Ming-Liang He.
Source: Dissertation Abstracts International, Volume: 72-01, Section: B, page: .
Thesis (Ph.D.)--Chinese University of Hong Kong, 2010.
Includes bibliographical references (leaves 111-129).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract also in Chinese.
33
Johnson, Karyn Nicole. "Molecular biology of Drosophila C Virus and studies on host susceptibility". Phd thesis, 1997. http://hdl.handle.net/1885/145395.
Texto completo da fonte
34
Lee, Albert Kim. "Characterizing Immune Responses to Marburg Virus Infection in Animal Hosts Using Statistical Transcriptomic Analysis". Thesis, 2018. https://doi.org/10.7916/D8S19JFC.
Texto completo da fonteResumo:
Marburg virus (MARV)–along with Ebola Virus–comprises Filoviridae, a family of virus which causes the life-threatening hemorrhagic fever in human and non-human primates for which there is no clinically approved vaccine. For this reason, this virus can potentially lend itself to pandemic and weapons of bioterrorism. Strikingly, this virus yields asymptomatic responses in its recently discovered host Rousettus aegyptiacus. Understanding of the interaction between MARV and different animal hosts will enable the improved understanding of filovirus immunology and the development of effective therapeutic agents. Although cell lines and primary cells have been used to investigate gene expression analysis of this virus, the transcriptomic view of MARV infection on the tissue samples of animal hosts has been an uncharted territory. The comprehensive analysis of transcriptome in hosts and spillover hosts will shed light on the immune responses on a molecular level and potentially allow the comparative analysis to understand the phenotypical differences. However, there have been gaps in resources necessary to carry the transcriptome research for MARV. For example, MARV host Rousettus aegyptiacus genome and transcriptome had not been available. Furthermore, the statistical machinery necessary to analyze multi-tissue/multi-time data was not available. In this dissertation, I introduce the two items that fill these gaps and show the application of the tools I built for novel biological discovery. In particular, I have built 1) the comprehensive de novo transcriptome reference of Rousettus aegyptiacus and 2) the Multilevel Analysis of Gene Expression (MAGE) pipeline to analyze the RNA-seq data with the complex experimental design. I show the application of MAGE in multi-time, multi-tissue transcriptome data of Macaca mulata infected with MARV. In this study, 15 rhesus macaques were sequentially sacrificed via aerosol exposure to MARV Angola over the course of 9 days, and 3 types of lymph node tissues (tracheobronchial, mesenteric, and inguinal) were extracted from each sample and sequenced for gene expression analysis. With MAGE pipeline, I discovered that the posterior median log2FC of genes separates the samples based on day post infection and viral load. I discovered the set of genes such as CD40LG and TMEM197 with interesting trends over time and how similar and different pathways have been influenced in three lymph nodes. I also identified the biologically meaningful clusters of genes based on the topology-based clustering algorithm known as Mapper. Using the MAGE posterior samples, I also determined the genes that are preferentially expressed in tracheobronchial lymph nodes. In addition to new analysis tools and biological findings, I built the gene expression exploration tool for biologists to examine differential gene expression over time in various immune-related pathways and contributing members of the pathways. In conclusion, I have contributed to the two important components in the transcriptome analysis in MARV research and discovered novel biological insights. The MAGE pipeline is modular and extensible and will be useful for the transcriptome research with the complex experimental designs which are becoming increasingly prevalent with the decrease in the cost of sequencing.
35
Maginnis, Melissa Sue. "Identification and characterization of cellular determinants of reovirus internalization". Diss., 2007. http://etd.library.vanderbilt.edu/ETD-db/available/etd-03302007-130416/.
Texto completo da fonte
36
Rezende, Melo Da Silva Carolina. "The role of the viral host response modifiers SPI-2 and N1L in mousepox pathogenesis". Phd thesis, 2011. http://hdl.handle.net/1885/150288.
Texto completo da fonteResumo:
The Orthopoxvirus genus includes highly-pathogenic viruses such as variola virus and ectromelia virus (ECTV). iECDTV is a natural pathogen of mice, causing mousepox and approximately 25% of its gene products are thought to be mediators of host immune evasion that target diverse processes.such as cellular signalling, intrinsic and extrinsic cell death pathways and components of the innate immune response. I studied the role of SPI-2 and NiL genes in mousepox and for that purpose recombinant ECTV were generated using GFP expression and blasticidin resistance as selection markers for transient dominant selection. The deletion of either or both SPI2 and NiL genes did not affect virus growth in vitro.
The serine proteinase inhibitor-Z (SPI-2) is a host response modifier known to inhibit caspase-8, caspase-I and granzyme B in vitro. I found that the ECTV SPI-2 protein is a potent inhibitor of infected target cell lysis induced by virus-immune cytotoxic T cells mediated by the death receptor pathway (caspase-dependent), but this viral protein has no effect on the granule exocytosis pathway. In the absence of SPI-2 protein, ECTV is attenuated in the infection of mousepox-susceptible mice; resulting in lower viral loads in the liver, decreased spleen pathology and substantially improved host survival. The main in vivo effect found of SPI-2 expression by ECTV-infected cells is the prevention of protective NK cell responses in a susceptible mouse infection. Reduced proportions and total numbers of NK cells expressing granzyme B were found in the spleen and blood of mice infected with wild-type (wt) ECTV compared to mice infected with SPI-2 mutant. Moreover, NK ex-vivo cytotoxicity was decreased in mice infected with wt ECTV compared to mice infected with mutant virus. Both virus attenuation and the improved immune responses associated with SPI-2 deletion from ECTV are lost when mice are depleted of NK cells. Consequently, SPI-2 renders mousepox lethal in susceptible strains by preventing protective NK cell defences.
The vaccinia virus NIL protein is a virulence factor known as a NF-KB signalling inhibitor and an antiapoptotic protein of the bc1-2 family, and was shown to inhibit NK cell responses in vivo. In the absence of NIL, ECTV is highly attenuated and susceptible mice survived mutant virus infection with doses at least 1000 higher than the lethal dose of wt virus. The viral loads in the spleen, liver and popliteal draining lymph nodes were greatly reduced in mice infected with mutant viruses compared to mice infected with wt virus, with reductions in the order of 105-fold in the spleen. Interestingly, serum IFN-y and IL-6 and the proportion ofNK and CD8 T cells expressing granzyme B in the spleen of mice infected with mutant viruses were reduced compared to mice infected with wt virus, suggesting that the attenuation observed in the ECTV NILL\ mutants may not simply be associated with improved cytotoxic immune responses.
37
Guglielmi, Kristen Marie. "Structure-function analysis of mammalian orthoreovirus attachment protein [sigma]1". Diss., 2008. http://etd.library.vanderbilt.edu/ETD-db/available/etd-03242008-110238/.
Texto completo da fonte
38
Tahiliani, Vikas. "Humoral immunity in secondary poxvirus infection". Phd thesis, 2010. http://hdl.handle.net/1885/151471.
Texto completo da fonteResumo:
The studies described in this thesis have utilised the orthopoxvirus ectromelia (ECTV), a natural mouse pathogen that causes a disease termed mousepox, to address the roles of specific innate cell types and T cell subsets in virus control during a secondary infection and more importantly, whether CD4{u207A} T cell help is important for generation of protective recall antibody responses. There are 3 key reasons why the experiments detailed in this thesis were undertaken. First, much of our current understanding of the induction and maintenance of long-lived antibody responses is based on studies using non-replicating model antigens, however, these may not be relevant to replicating viruses. Second, humoral immunity to smallpox (caused by the orthopoxvirus variola), has been reported to be stable and last longer than memory CD4{u207A} or CD8{u207A} T cell responses. Third, recent studies from the ECTV and monkeypox virus models suggest that T cell responses may be redundant but antibody is necessary and sufficient for recovery from a secondary infection. The current thinking in the poxvirus field is that CD4{u207A} T cell help is not required for recall antibody responses for recovery from secondary poxvirus infection. To study the requirements for protection against secondary infection, a prime-challenge regime was used, in which avirulent ECTV (ECTV-TK{u207B}) was used to prime mice that were then challenged with virulent ectromelia virus (ECTV-WT). In mice primed with ECTV-TK{u207B}, the level of virus-neutralizing Ab returned to minimal levels 35 days after priming. Based on this observation it was assumed that the ECTV-TK{u207B} might not be efficient in inducing a B cell memory response. Results presented in Chapter 3 established that mice primed with ECTV-TK{u207B} were able to induce an efficient memory response through the induction of long-lived ECTV - specific ASCs. Neutrophils, plasmacytoid dendritic cells (pDCs), natural killer (NK) cells, T cell subsets and antibody are critical for recovery of mice from primary ECTV infection. Previous studies have shown that recovery of mice from the acute phase of secondary ECTV infection is strictly dependent on antibody responses and does not require CD4{u207A} T cell help or effector functions of CD8{u207A} cytotoxic T lymphocytes. However, neutrophils, pDC and NK cells could contribute to virus control in the absence of T cell subsets. The results presented in Chapter 4 show that the ability of mice individually depleted of neutrophils, pDC and NK cells subsets with specific monoclonal antibodies to overcome a secondary ECTV challenge was not diminished but concurrent depletion of NK cells, pDCs and neutrophils affected virus control and this was clearly evident when one or more T cell subsets were also depleted. Mice depleted of one or both T cell subsets, NK cells, pDCs and neutrophils were unable to control viral load, had a severe reduction in ECTV -specific ASCs and a reduction in the serum neutralising antibody response. Thus, the antibody response alone is not sufficient to mediate protection during the acute phase of secondary ECTV infection. The roles of CD4{u207A} T cell help for antibody production and effector functions of CD8{u207A} T cells over the longer term, past the acute stage of a secondary infection, were canvassed in Chapter 5. Although CD4{u207A} T cell help was apparently not required during the acute phase of a secondary infection, this subset was clearly important in the maintenance of ECTV-specific long-lived ASCs and in the generation of neutralizing antibody as the infection progressed and the response developed. In the continued absence of CD4{u207A} T cells over 35 days post-challenge (achieved by CD4{u207A} T cell depletion), there was a significant increase in the viral load, which correlated with a reduction in ECTV-specific ASCs in the BM, a significant reduction in splenic GC B cells and a significant decrease in levels of virus-neutralizing antibody by D 35 p.c. This was further confirmed using the HEL-specific B cell receptor transgenic system and recombinant viruses that express a mutant version of the antigen, hen-egg lysozyme (HEL) as a viral envelope protein. In spleens of mice depleted of CD4{u207A} T cells, there was a reduction in SW(HEL) GC B cells and a significant decrease in SWHEL GC B cells by D 35 p.c., which SW(HEL) correlated with the reduction in levels of anti-HEL IgG. The effector function of CD8{u207A} T cells becomes critical for virus control in the absence of CD4{u207A} T cells. In the absence of CD4{u207A} T cell help, the effector molecules perforin and possibly granzymes A and B expressed by CD8{u207A} T cells contribute to viral control during the later phases of secondary ECTV infection. Taken together, the results from experiments reported in this thesis provide key findings on the mechanism(s) of protection during a secondary ECTV infection during the acute phase (6-8 days post-challenge), maintenance phase (9-21 days post-challenge) and the long-term maintenance (22-35 days post-challenge). During the acute phase of a secondary ECTV infection, the NK cells, pDCs, neutrophils, T cells and extrafollicular antibodies are important in mediating protection. As the infection progresses, the extrafollicular response continues to be important in mediating protection during the maintenance phase of infection in the absence of CD4{u207A} T cell help. However as the infection further progresses, CD4{u207A} T cell help becomes important for long-term maintenance of antigen-specific memory B cells and long-lived ASCs. Protection mediated during this phase of infection requires CD4{u207A} T cell helper-dependent production of ECTV-specific antibody and also CD8{u207A} T effector cells.
39
Wang, Gary Zhe. "Host factors regulating retroviral replication by interactions with viral RNA and DNA". Thesis, 2016. https://doi.org/10.7916/D8028RHK.
Texto completo da fonteResumo:
Retroviruses are capable of infecting diverse vertebrates, and successful infection requires intimate interaction between virus and the host cell. During an infection, retroviral particles must bind specifically to cell surface receptors on the target cell, cross the plasma membrane, reverse-transcribe their RNA genome into double stranded DNA, find their way to the nucleus, enter the nucleus and integrate its DNA into host chromosomes. Following integration, expression of viral mRNA ensues, followed by viral mRNA export into the cytoplasm, translation of viral mRNA into proteins, and assembly of new virions that will egress from the host cell. We now appreciate that at many steps of this complex process, the virus must hijack the cellular machinery to replicate. At the same time, the host cell mobilizes a variety of cellular defense mechanisms to suppress viral infection. This thesis investigates various aspects of virus-host interactions. I will first describe the involvement of cellular transcriptional repressor protein ErbB3 binding protein 1 (EBP1) in facilitating transcriptional shutdown of Moloney murine leukemia virus (MLV) gene expression in mouse embryonic cells. Next, I describe a novel means of regulating the activity of Yin Yang 1 (YY1), a cellular transcription factor regulating retroviral gene expression, through post-translational modifications. I show that YY1 is a target of tyrosine phosphorylation by Src family kinases. Phosphorylation of YY1 impairs its ability to bind DNA and RNA, thereby downregulating its activity as a transcription factor on retroviral and cellular promoters. Apart from studying retroviral gene expression, I have also investigated intrinsic cellular defenses against retroviral infection. This is exemplified by our finding that mouse cells are intrinsically resistant to infection by betaretroviruses such as Mason-Pfizer monkey virus (M-PMV). The block against M-PMV occurs after reverse transcription and prior to viral nuclear entry. Finally, I will present ongoing work examining the fate of viral DNAs following infection, focusing on the kinetics of its association with cellular core histones and viral structural proteins. Together, this work provides critical insights into numerous aspects of the virus-host interactions.
40
Umbach, Jennifer Lin. "Analysis of the Interaction between Viruses, Mirnas and the Rnai Pathway". Diss., 2008. http://hdl.handle.net/10161/596.
Texto completo da fonte
41
"Systemic lupus erythematosus: from immunopathology to viral pathogenesis". Thesis, 2008. http://library.cuhk.edu.hk/record=b6074590.
Texto completo da fonteResumo:
Results of the above studies thus suggested that immune dysregulation in SLE result in derangement of a spectrum of inflammatory mediators leading to possible multiple organs auto-inflammatory damages. However, the exact etio-pathogenic mechanism could not simply be explained by these phenomena. Infection has been invoked as an underlying etiology or trigger for the induction of autoimmune disease. Epstein-Barr virus (EBV) possesses multiple features that characterise its involvement in initiating or perpetuating SLE disease. Several research groups demonstrated that the peripheral blood EBV DNA load is significantly higher in SLE patients, yet cell-free viral DNA was also reported in other EBV-associated diseases such as nasopharyngeal carcinoma (NPC) and certain lymphomas, suggesting that relatively little is known about its biology and dynamic distribution in the blood circulation. In the second part of our study, we examined the cell-free and cell-associated distribution profile of EBV DNA load in SLE. Our data showed that the distribution of EBV DNA in the cell-free and cell-associated compartments exhibited a heterogeneous pattern in SLE patients. Contrary to the exclusive presence of circulating cell-free EBV DNA in NPC patients, both cell-free and cell-associated EBV DNA were detected in some SLE patients, while in others, no EBV DNA was measurable in either blood compartments. The level of cell-associated EBV viral load was significantly higher in SLE patients with active disease than those who presented with milder disease activity. This phenomenon indicated a possible association of EBV viral infection with the level of immune competence in SLE patients. It has been reported that EBV encodes proteins which shares significantly homology sequence with human IL-6, IL-8, IL-10, IL-12 and colony-stimulating factor (CSF)-1. This proposition brought our attention to the immune perturbation by EBV on the cytokine balance, possibly constitute in part, to the immune dysregulation and Th1 and Th2 dichotomy in SLE exacerbation. (Abstract shortened by UMI.)The first section of this research study aimed to explore the messengers that influence Th1/Th2 cells differentiation, development, effector functions and hence their plausible contribution in SLE immunopathogenesis. We focused on studying the expression of cytokine and chemokine milieu that directs the traffic of T lymphocytes; co-stimulatory molecules in the activation of T lymphocytes; transcription factors T-bet and GATA-3 in regulating the differentiation of Th1 and Th2 cell lineage. We also investigated the involvement of the lymphocyte subpopulation, Th17 in the auto-inflammatory axis of SLE exacerbation.
Lit, Choi Wan.
Advisers: Christopher W.K. Lam; Y.M. Dennis Lo.
Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3358.
Thesis (Ph.D.)--Chinese University of Hong Kong, 2008.
Includes bibliographical references (leaves 203-235).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstracts in English and Chinese.
School code: 1307.
42
Byrd, Daniel James. "Vaccinia Virus Binding and Infection of Primary Human Leukocytes". Thesis, 2014. http://hdl.handle.net/1805/5279.
Texto completo da fonteResumo:
Indiana University-Purdue University Indianapolis (IUPUI)Vaccinia virus (VV) is the prototypical member of the orthopoxvirus genus of the Poxviridae family, and is currently being evaluated as a vector for vaccine development and cancer cell-targeting therapy. Despite the importance of studying poxvirus effects on the human immune system, reports of the direct interactions between poxviruses and primary human leukocytes (PHLs) are limited. We studied the specific molecular events that determine the VV tropism for major PHL subsets including monocytes, B cells, neutrophils, NK cells, and T cells. We found that VV exhibited an extremely strong bias towards binding and infecting monocytes among PHLs. VV binding strongly co-localized with lipid rafts on the surface of these cell types, even when lipid rafts were relocated to the cell uropods upon cell polarization. In humans, monocytic and professional antigen-presenting cells (APCs) have so far only been reported to exhibit abortive infections with VV. We found that monocyte-derived macrophages (MDMs), including granulocyte macrophage colony-stimulating factor (GM-CSF)-polarized M1 and macrophage colony-stimulating factor (M-CSF)-polarized M2, were permissive to VV replication. The majority of virions produced in MDMs were extracellular enveloped virions (EEV). Visualization of infected MDMs revealed the formation of VV factories, actin tails, virion-associated branching structures and cell linkages, indicating that infected MDMs are able to initiate de novo synthesis of viral DNA and promote virus release. Classical activation of MDMs by LPS plus IFN-γ stimulation caused no effect on VV replication, whereas alternative activation of MDMs by IL-10 or LPS plus IL-1β treatment significantly decreased VV production. The IL-10-mediated suppression of VV replication was largely due to STAT3 activation, as a STAT3 inhibitor restored virus production to levels observed without IL-10 stimulation. In conclusion, our data indicate that PHL subsets express and share VV protein receptors enriched in lipid rafts. We also demonstrate that primary human macrophages are permissive to VV replication. After infection, MDMs produced EEV for long-range dissemination and also form structures associated with virions which may contribute to cell-cell spread.
43
Dias, Jose Alberto Caram de Souza. "The relationship of potato leafroll virus concentration in the host and vector to disease spread". 1988. http://catalog.hathitrust.org/api/volumes/oclc/20388123.html.
Texto completo da fonteResumo:
Thesis (Ph. D.)--University of Wisconsin--Madison, 1988.Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 310-339).
44
Huang, Ching-Ing, e 黃瀞瑩. "The study of the relationship between Bamboo mosaic virus ?infection and its downregulated host gene NbTFIISL from Nicotiana benthamiana". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/33672067394055047419.
Texto completo da fonteResumo:
碩士國立中興大學
生物科技學研究所
102
Abstract Bamboo mosaic virus (BaMV) belongs to the Potexvirus genus of Flexiviridae family and has a single-stranded positive-strand RNA genome. To understand the infection mechanism BaMV, our lab has selectively detected and isolated 90 differentially expressed genes from Nicotiana benthamiana post BaMV infection using cDNA-Amplified Fragment Length Polymorphism (cDNA-AFLP) technique. In my study, one of the downregulated cDNA fragments, ACAC5-2, has no significant match to any known sequence in the databases. The relative coat protein accumulation level of BaMV in inoculated leaves of ACAC5-2 knockdown N. benthamiana plants declined to about 60% that of the control. Furthermore, the coat protein of BaMV in the ACAC5-2 knockdown protoplasts does not show significant change compared to that of the control protoplasts at 24 and 48 hrs post inoculation. These results suggest that the downregulated gene ACAC5-2 could be involved in the cell to cell movement of BaMV. Moreover, The full-length cDNA of ACAC5-2 from N. benthamiana transcriptome database was obtained after up- and down- stream extension by the Rapid Amplification of cDNA Ends (RACE) technique. It could be encoded a 992-amino acid polypeptide comprising a TFIIS N-terminal domain, a conserved protein binding domain found in Transcription Factor IIS, Med26, Elongin A and other transcription elongation factors located at the N-terminal region of this polypeptide. Therefore, this gene was designated NbTFIISL. We further fused this gene with mOrange2 to generate pEyon-NbTFIISL-OFP construct which then transiently expressed by agro-infiltration. The fluorescent signal predominantly located at the nucleus was observed under confocal microscopy. The future work will be focusing on the relationship between this protein and BaMV infection.
45
Lanza, Andre Syd, e 藍安杰. "A Study on the Relationship between Nucleolar Localization of the Nervous Necrosis Virus Capsid Protein and Host Gene Expression". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/vp54vu.
Texto completo da fonteResumo:
碩士國立臺灣海洋大學
水產養殖學系
107
Nervous necrosis virus (NNV) is a devastating fish virus causing mass mortality in juvenile fish and causing significant economic losses in the grouper aquaculture industry in South East Asia. Treatment and control of the disease is difficult primarily because the molecular basis of pathogenicity of the virus is still not fully understood. It has previously been demonstrated that the viral capsid protein (CP) localizes to the nucleolus in fish cells signifying some role it may have in controlling gene expression of the host. We employed a PCR site-directed mutagenesis method to delete or mutate a nucleolar localization sequence (NoLS) located on the capsid protein thus generating the mutant capsids NoLSDel and 29AlaMut. Confocal microscopy showed that nucleolar localization of the NNVCP was completely blocked in GK cells transfected with NoLSDel at 3 hours and 24 hours post transfection, however the cells transfected with 29AlaMut still showed 29% and 100% localization to the nucleolar periphery at 3 hours and 24 hours post transfection, respectively. RNA samples were collected from cells transfected with the wild type or mutant capsids and sequenced for transcriptomic analysis, and it was revealed that the regulatory effects of NNVCP nucleolar localization occur quite early after at 3 hours after introduction of the NNVCP. Genes related with cell protein expression, proteolysis, cell cycle control and nuclear import were most influenced by NNVCP nucleolar localization. These genes were also affected during viral infection. Interestingly, luciferase activity was also upregulated in cells primed with the NNVCP. Development of therapeutic or prophylactic strategies that disrupt nucleolar localization of the NNVCP or its downstream effects would help alleviate the economic pressures on the aquaculture industry brought about by NNV.