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1
Bergaoui, Ramzi. "Epidémiologie de la maladie de West Nile en Tunisie." Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20055/document.
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Nous avons cherché à mieux comprendre la situation épidémiologique du virus West Nile (VWN) en Tunisie. Nous avons tout d'abord produit une carte du risque de transmission du VWN aux équidés montrant un risque élevé dans de nombreuses régions, dépendant de facteurs environnementaux : zones humides et climat favorables aux populations d'oiseaux sauvages et de moustiques. Le taux élevé de séroprévalence observé chez les équidés est compatible avec l'hypothèse d'une circulation endémique du VWN sans exclure la possibilité d'introductions répétées.Une étude complémentaire a démontré l'exposition des oiseaux domestiques, péri-domestiques et sauvages au VWN et a permis d'établir un premier inventaire des espèces d'oiseaux les plus exposées, pouvant servir de base à un système de surveillance de l'avifaune sauvage en Tunisie.Le suivi sérologique mensuel de poules sentinelles a permis de détecter la circulation du virus en fin de saison chaude (septembre, octobre) à proximité de zones humides pendant une période de forte activité des moustiques et d‘abondance des oiseaux sauvages. L'occurrence simultanée de cas humains de fièvre West Nile (FWN) laisse penser qu'un système de poules sentinelles serait utile pour une alerte précoce de recrudescence de l'activité du VWN.A l'issue de ce travail, nous proposons des pistes pour un système de surveillance multidisciplinaire de la FWN, adapté au contexte tunisien, et devant permettre la détection précoce de toute circulation viraleOur investigations aimed at clarifying some aspects of the West Nile virus (WNV) epidemiological situation in Tunisia, and in particular at identifying areas at high risk of WNV circulation. A major achievement was the establishment of a risk map for the transmission of WNF in horses. This map shows that the risk of transmission strongly depends on environmental factors: increased risk associated to wetlands proximity and climatic factors favourable to wild birds and mosquitoes. The high seroprevalence observed in horses is compatible with an endemic circulation of WNV without excluding the possibility of repeated introductions.Another study in birds showed the exposure of domestic, wild resident and migratory birds to WNV, and helped establishing an initial inventory of bird species most exposed to WNV. These studies can serve as a basis for a monitoring system of wild birds in Tunisia.A system of monthly follow-up of sentinel chickens detected virus circulation at the end of the hot season (September, October), near wetlands and during a period of high mosquito activity, and abundance of wild birds. The simultaneous occurrence of human cases of WNF brought us to suggest that active surveillance in sentinel chickens would be useful for early warning of increased activity of WNV. This work allows us to propose trails for a WNV multidisciplinary monitoring system adapted to the Tunisian situation, enabling early detection of viral circulation
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Schneeweiß, Anne. "Entwicklung eines DNA-Impfstoffs am Beispiel West-Nil-Virus." Doctoral thesis, Universitätsbibliothek Leipzig, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-82906.
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Das West-Nil-Virus (WNV) ist eine Zoonose mit weltweit zunehmender Verbreitung. Natürliches Reservoir dieses Flavivirus sind Vögel, aber auch Säugetiere wie z.B. Menschen können infiziert werden. In einigen Fällen führt eine WNV-Infektion zu schweren neurologischen Erkrankungen. Infolgedessen werden effektive und biologisch sichere Impfstrategien gegen dieses Virus benötigt. Eine Alternative zu herkömmlichen Impfmethoden beschreibt die DNA-Immunisierung. In dieser Arbeit wurde ein potentieller DNA-Impfstoff gegen das WNV hergestellt. Die Immunisierung des DNA-Vektors induzierte starke zelluläre und humorale Immunantworten in Mäusen. Zudem waren die Tiere gegen eine WNV-Infektion geschützt. Zusätzliche Impfungen mit rekombinantem WNV-Protein führten zu einer weiteren Steigerung der Immunogenität des DNA-Impfstoffkandidaten.
Des Weiteren sollte der nicht-virale Gentransfer im Allgemeinen optimiert werden. Ein neu entwickeltes Transportsystem für Plasmid-DNA, bestehend aus natürlichen Histonextrakten und Polyethylenimin, resultierte in einer verbesserten Proteinexpression in in vitro transfizierten Zellen und wurde von diesen sehr gut toleriert. Daher wäre diese Strategie auch für zukünftige DNA-Impftechniken denkbar.
Der Einfluss von WNV auf die Expression zellulärer miRNAs in Wirtszellen wurde bisher noch nicht untersucht. Dennoch könnten auf diese Weise potentielle molekulare Biomarker für eine frühe WNV-Diagnose identifiziert werden. Mittels Microarray-Technik wurde die Expression zellulärer miRNAs analysiert. Verschiedene miRNA-Spezies waren infolge einer WNV-Infektion leicht herunter- bzw. hochreguliert und stellen mögliche diagnostische Biomarker für das Virus dar.
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Aravapalli, Sridhar. "Dengue virus and West Nile virus protease inhibitors." Diss., Wichita State University, 2013. http://hdl.handle.net/10057/6719.
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Dengue virus and West Nile virus are important mosquito-borne pathogens of Flaviviridae family affecting millions of people worldwide and causing a severe global healthcare threat. However, currently there are no approved effective antiviral drugs or vaccines available for the treatment of virus infection. This thesis describes the design, synthesis and discovery of two novel classes of reversible competitive inhibitors of Dengue Virus and West Nile Virus NS2B/NS3 protease. Structure-activity relationship studies have led to the identification of a low micromolar hit, which will be used in a hit-to-lead campaign to generate lead compounds that display superior ADMET and PK characteristics.Thesis (Ph.D.)--Wichita State University, Fairmount College of Liberal Arts and Sciences, Dept. of Chemistry
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Shelite, Thomas Robert. "West Nile virus and wild bird populations." Diss., Click here for available full-text of this thesis, 2006. http://library.wichita.edu/digitallibrary/etd/2006/t076.pdf.
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Shelite, Thomas R. "West Nile virus and wild bird populations." Thesis, Wichita State University, 2006. http://hdl.handle.net/10057/391.
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West Nile Virus (WNV) first appeared in the western hemisphere in 1999, and has since spread across the United States and into Mexico and the Caribbean. It has been
hypothesized that WNV has spread rapidly via migratory birds, and that various avian
species may facilitate viral amplification during winter months. The goals of this research were to determine the role of American Tree Sparrows (Spizella americana) in the spread of WNV during their igrations and to determine the role of the Northern Cardinal (Cardinalis cardinalis) in winter survivorship and subsequent spring amplification of WNV. Additional wintering avian species were sampled to provide a general survey of the prevalence of WNV in winter in south-central Kansas. Blood samples were taken from the brachial vein of migratory and wintering birds captured using mist nets at four wintering feeding stations at the Wichita State University Field Station. Some samples were taken from retrapped birds within a single winter to determine if winter transmission occurs. Some birds were resampled in consecutive winters to monitor seroconversion rates. Analysis of serum samples were performed, in triplicate, using an epitope-blocking ELISA. The current study was conducted during the consecutive winters of 2003-04 and 2004-05. It was concluded that resident species had an increased incidence of WNV
exposure when compared to that of migratory species. This difference suggests that
migratory species may not have as important a role in the dissemination of WNV as first
hypothesized. Also, minimal, if any, winter transmission occurs on communal feeding
grounds. Viral amplification during the winter was not demonstrated, although one
individual seroconverted during a single winter.Thesis (M.S.)--Wichita State University, Dept. of Biological Sciences
Includes bibliographical references (leaves 35-39)
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Reed, Andrew J. "Biogeography of West Nile Virus in Ohio." Bowling Green State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1609806272985721.
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Zakhia, Renée. "Epidemiology of West Nile Virus in Lebanon." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066466/document.
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Le Virus du Nil Occidental (VNO) et le Virus de la Fièvre de la Vallée du Rift (VFVR) sont deux arbovirus transmis par le moustique Culex pipiens comprenant deux biotypes: pipiens et molestus. Au cours de ce projet, nous avons évalué la circulation du VNO au Liban dans des populations de moustiques, des humains, des chevaux et des poulets. Nous avons aussi évalué la compétence vectorielle des populations locales de Cx. pipiens à transmettre le VNO et le VFVR.Des moustiques ont été récoltés et testés pour la présence d’un gène spécifique du VNO. En plus, des sérums humains, de chevaux et de poulets ont été analysés pour rechercher des anticorps spécifiques par ELISA puis confirmés par neutralisation. En outre, des spécimens de Cx. pipiens ont été infectés avec la lignée 1 du VNO ou la souche de VFVR Clone 13. Ensuite, les taux d’infection, de dissémination et de transmission ont été déterminés à différents jours après infection des moustiques. La compétence vectorielle a été comparée entre les différents biotypes.Les résultats entomologiques ont révélé que Cx. pipiens est dominant (87.2%). Tous les moustiques analysés étaient négatifs pour le VNO. Les taux de séroprévalence étaient de 1.01% et 1.98% parmi les humains et les chevaux respectivement. De plus, Cx. pipiens s’est révélé bien plus compétent pour transmettre le VNO que le VFVR. Le biotype molestus est capable de transmettre le VNO plus tôt que celui de pipiens. Cette étude présente des preuves sur une faible circulation du VNO au Liban. Cx. pipiens s’est révélé compétent pour assurer cette transmission. Ainsi, il est essentiel d'établir des programmes de surveillance pour prévenir les éventuelles épidémiesWest Nile virus (WNV) and Rift Valley Fever virus (RVFV) are two emerging arboviruses that have never been reported in Lebanon. They can be transmitted by Culex pipiens mosquito species including two biotypes: pipiens and molestus. During this project, we assessed the circulation of WNV among mosquitoes, human, horse and chicken populations in Lebanon. Moreover, we evaluated, under experimental conditions, the capacity of local Cx. pipiens biotypes to transmit both viruses.Adult mosquitoes were collected, identified and tested to detect WNV RNA. Besides, human, horse and chicken blood samples were collected and screened for WNV antibodies using an in-house ELISA and then confirmed by neutralization assay. Moreover, local Cx. pipiens specimens were experimentally infected with WNV lineage 1 or RVFV Clone 13 strain. The viral infection, dissemination and transmission were then estimated at different days post infection.The vector competence was compared between Cx. pipiens biotypes.Entomological results revealed that 87.2% of collected adult mosquitoes were Cx. pipiens. Screened mosquitoes were negative for WNV. Seroprevalence rates were 1.01% and 1.98% among humans and horses respectively. Besides, local Cx. pipiens were highly competent for WNV transmission and to a lesser extent to RVFV. The molestus biotype was able to transmit WNV earlier than pipiens biotype.The present study provides new evidence of a low circulation of WNV among human and horses in Lebanon. Cx. pipiens is the suspected vector and is experimentally competent to ensure transmission. Therefore, there is a need to establish surveillance program to predict and prevent potential outbreaks
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Shrestha, Bimmi. "A study of pathogenesis of West Nile virus encephalitis in the adult murine model." Phd thesis, Department of Pathology, 2002. http://hdl.handle.net/2123/9297.
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Schneeweiß, Anne. "Entwicklung eines DNA-Impfstoffs am Beispiel West-Nil-Virus." Doctoral thesis, Fraunhofer Institut für Zelltherapie und Immunologie, 2011. https://ul.qucosa.de/id/qucosa%3A11341.
Full textAbstract:
Das West-Nil-Virus (WNV) ist eine Zoonose mit weltweit zunehmender Verbreitung. Natürliches Reservoir dieses Flavivirus sind Vögel, aber auch Säugetiere wie z.B. Menschen können infiziert werden. In einigen Fällen führt eine WNV-Infektion zu schweren neurologischen Erkrankungen. Infolgedessen werden effektive und biologisch sichere Impfstrategien gegen dieses Virus benötigt. Eine Alternative zu herkömmlichen Impfmethoden beschreibt die DNA-Immunisierung. In dieser Arbeit wurde ein potentieller DNA-Impfstoff gegen das WNV hergestellt. Die Immunisierung des DNA-Vektors induzierte starke zelluläre und humorale Immunantworten in Mäusen. Zudem waren die Tiere gegen eine WNV-Infektion geschützt. Zusätzliche Impfungen mit rekombinantem WNV-Protein führten zu einer weiteren Steigerung der Immunogenität des DNA-Impfstoffkandidaten.
Des Weiteren sollte der nicht-virale Gentransfer im Allgemeinen optimiert werden. Ein neu entwickeltes Transportsystem für Plasmid-DNA, bestehend aus natürlichen Histonextrakten und Polyethylenimin, resultierte in einer verbesserten Proteinexpression in in vitro transfizierten Zellen und wurde von diesen sehr gut toleriert. Daher wäre diese Strategie auch für zukünftige DNA-Impftechniken denkbar.
Der Einfluss von WNV auf die Expression zellulärer miRNAs in Wirtszellen wurde bisher noch nicht untersucht. Dennoch könnten auf diese Weise potentielle molekulare Biomarker für eine frühe WNV-Diagnose identifiziert werden. Mittels Microarray-Technik wurde die Expression zellulärer miRNAs analysiert. Verschiedene miRNA-Spezies waren infolge einer WNV-Infektion leicht herunter- bzw. hochreguliert und stellen mögliche diagnostische Biomarker für das Virus dar.
10
Eichler, Elizabeth Ann. "Public Attitudes, Knowledge and Practices on West Nile Virus." Master's thesis, Temple University Libraries, 2011. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/164048.
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Public HealthM.S.
Objective: To develop an original survey on public attitudes, knowledge and practices on West Nile Virus (WNV), mosquitoes, and pesticides. We sought to gain insight on what personal protective behaviors (PPBs) are used by the public and whether the public is supportive of pesticide use in combating the threat of WNV. An effective WNV control program must take into account the public's attitudes regarding PPBs and what would influence their use of PPBs. The survey findings will be used to develop a new educational plan for the West Nile Virus Surveillance and Control Program of Delaware County. We sought to determine if knowledge and concern about one's personal risk of contracting WNV were driving forces in one's use of PPBs and support of pesticide use. Results: The sample population was highly informed on WNV and used many PPBs. Knowledge of WNV and concern about contracting WNV were not significant predictors of PPB use or pesticide support. However, odds ratios indicate an increased odds of being in the high PPB group with increasing knowledge. Knowing someone who has or has had WNV was a factor in PPB use, although the outcome of WNV infection is rarely reported. Older age predicted greater PPB use while higher education predicted a lack of support for pesticide use. Conclusion: Future surveys of the public knowledge will need to reach a more diverse population than that of the current study. It appears that many people are using PPBs despite not believing in their efficacy at preventing mosquito bites and WNV. Future studies should seek to identify what is motivating people to use these PPBs, besides knowledge of WNV and concern for their health.
Temple University--Theses
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Cox, Darren Anthony. "Modulation of Murine Haematopoietic Responses During Viral Encephalitis and Other Inflammatory Diseases." Thesis, The University of Sydney, 2019. https://hdl.handle.net/2123/21381.
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During homeostatic conditions replenishment of the hematopoietic system occurs through the constitutive release of differentiated cells from the bone marrow to the circulatory system. Depletion of these mature immune cells during an immune response results in a compensatory haematopoietic response that can involve suppression or amplification of haematopoiesis as well as phenotypical and functional variation of progenitor cells. However, in many cases lymphopoiesis is often suppressed and is usually concomitant with amplification of myelo and granulopoiesis in a process known as “emergency granulopoiesis”. Here I investigated the effect of central nervous system (CNS) infection with West Nile Virus (WNV) on the lymphopoietic modulation in the bone marrow and conducted comparative studies using a diverse range of disease models, including ZIKV and lymphocytic choriomeningitis viruses (LCMV), as well as parasitic malaria infection. Our results suggest that both WNV and ZIKV act in a very similar way during late stage lethal infection to deplete the early and intermediate developing B cells, primarily via cell cycle interruption and subsequent proliferative suppression in a TNF dependent manor. I demonstrated that these similarities extend to other lethal disease models with similar phenomena observed in both acute LCMV and cerebral malaria models. In contrast, while there was an overall decline in the number of bone marrow B cells during chronic infection models, I observed an increase in the number of early stage pro B cells, but no evidence of increased proliferation, suggesting lymphopoietic modulation tends towards expansion of these early cell populations at a point prior to the pro B stage of development. It is also possible that the presence of encephalitis or encephalopathy results in a response that abrogates this expansion. In contrast to previous influenza studies, I found in vivo evidence to suggest that the depletion of early stage B cells is, at least partly, associated with an increase in apoptosis during both WNV and ZIKV infections. In addition, I ruled out mobilisation of transitional B cells and other, less developed cell populations to the periphery during WNV infection as an explanation for these changes. Interestingly, I show evidence to suggest that cells, classically seen as irreversibly locked to the B cell lineage, can be diverted away from the classic B cell development pathway. Finally, I conclude that the depletion of early-stage bone-marrow B cells during WNV and ZIKV infections is primarily associated with cell cycle inhibition and these cells likely undergo apoptosis. I also propose that a small proportion of these cells are subject to phenotypic diversion away from the classic B cell lineage.
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Costa, Ana Catarina de Almeida. "Serological surveillance of West Nile virus and molecular diagnostic of West Nile virus, Usutu virus, avian influenza and Newcastle disease virus in wild birds of Portugal." Master's thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2021. http://hdl.handle.net/10400.5/21604.
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Dissertação de Mestrado Integrado em Medicina VeterináriaABSTRACT - The worldwide changes in the environment and climate of natural ecosystems detected in the last few decades have been responsible for the emergence of new infectious diseases in both animals and humans. This work focused on surveillance of four zoonotic pathogens, namely West Nile virus (WNV), Usutu virus (USUV), avian orthoavulavirus-1 (AOaV-1), also known as Newcastle disease virus (NDV), and influenza A virus (IAV) in wild birds of continental Portugal. Blood and tissues samples from both live and dead birds (were collected in three wildlife rehabilitation centres of Portugal between 2018 and 2019: Wildlife Rehabilitation and Research Centre of Ria Formosa, Wildlife Rehabilitation Centre of Lisbon and University of Trás-os-Montes and Alto Douro Veterinary Teaching Hospital – Wildlife Rehabilitation Centre. Samples from a total of 192 animal were collected (82 in vivo and 110 post-mortem). A total of one hundred and eighty-two samples were tested for WNV, USUV, IAV and for AOaV-1 by real time RT-PCR (RT-qPCR) or RT-PCR. AOaV-1 positive samples from two Eurasian collared doves (Streptopelia decaocto) (1.10% sample positivity) collected in the south of Portugal were sequenced, and their phylogenetic relationships analysed. Phylogenetic analysis confirmed that these sequences clustered with other AOaV-1 sequences from genotype XXI, subgenotype XXI.2. Tissue samples were all negative for WNV, USUV and IAV. Plasma samples were also tested for WNV antibodies by seroneutralization test. WNV neutralizing antibodies were detected in ten (13.70%) out of 73 samples namely: four Buteo buteo, two Hieraaetus pennatus, an Accipiter nisus, a Aegypius monachus, a Circaetus gallicus, and a Ciconia ciconia. This study has established a baseline for future epidemiological studies of WNV and AOaV-1 in wild birds of continental Portugal. Further monitoring and epidemiological studies of both diseases in Portugal is advised, considering the threat that both diseases can pose to humans, animals and to the ecosystems themselves.
RESUMO - MONITORIZAÇÃO SEROLÓGICA DO VÍRUS DO NILO OCIDENTAL E DIAGNÓSTICO MOLECULAR DO VÍRUS DO NILO OCIDENTAL, VÍRUS USUTU, INFLUENZA AVIÁRIA E VÍRUS DA DOENÇA DE NEWCASTLE EM AVES SELVAGENS DE PORTUGAL - As profundas alterações ambientais e climáticas dos ecossistemas naturais que o mundo tem sofrido nas últimas décadas têm sido responsáveis pelo aparecimento de novas doenças infeciosas em animais e humanos. Este trabalho focou-se na monitorização de quatro agentes zoonóticos em aves selvagens de Portugal continental, nomeadamente vírus do Nilo Ocidental (WNV), vírus Usutu (USUV), orthoavulavirus-1 aviário, também conhecido como vírus da doença de Newcastle (NDV) e vírus influenza A (IAV). Amostras de sangue e tecidos de animais vivos e mortos foram recolhidas entre 2018 e 2019 em três centros de recuperação de fauna selvagem em Portugal: Centro de Recuperação e Investigação de Animais Selvagens da Ria Formosa, Centro de Recuperação de Animais Silvestres de Lisboa e Centro de Recuperação de Animais Selvagens do Hospital Veterinário da UTAD. Foram recolhidas amostras de um total de 192 animais (82 in vivo e 110 post-mortem). Um total de cento e oitenta e duas amostras foram testadas para a presença de WNV, USUV, IAV e AOaV-1 por RT-PCR em tempo real (RT-qPCR) e RT-PCR convencional. Duas amostras positivas de duas rolas turcas (Streptopelia decaocto) (1.10% positividade) recolhidas no sul de Portugal foram sequenciadas e as suas relações filogenéticas foram analisadas. A análise filogenética confirmou que estas sequências agrupam com estirpes de AOaV-1 do genótipo XXI, subgenótipo XXI.2. Amostras de tecidos foram todas negativas para a presença de WNV, USUV e IAV. Amostras de plasma foram testadas para a presença de anticorpos neutralizantes de WNV pelo teste da seroneutralização. Das 73 amostras, dez (13.70%) apresentavam anticorpos neutralizantes para WNV: quatro Buteo buteo, duas Hieraaetus pennatus, um Accipiter nisus, um Aegypius monachus, uma Circaetus gallicus e uma Ciconia ciconia. Este estudo estabeleceu uma base para futuros estudos epidemiológicos sobre WNV e AOaV-1 em aves selvagens em Portugal continental. Aconselha-se a realização futura de outros estudos epidemiológicos e monitorizações, considerando a ameaça que ambas as doenças apresentam para humanos, animais e para os próprios ecossistemas.
N/A
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Bahuon, Céline. "Construction d’un clone infectieux d’une souche méditerranéenne du Virus West Nile, validation de ses propriétés biologiques et développement de nouveaux modèles d’évaluation de la virulence." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA114828/document.
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Le virus West Nile (VWN) est un virus neurotrope principalement transmis par piqûre de moustique et dont le réservoir est constitué par la faune aviaire sauvage. Les souches circulant en Europe appartiennent à 4 lignages génétiques différents à l’origine de nombreuses épidémies d’ampleur modérée à faible et limitées géographiquement, contrairement à ce qui a été observé en Amérique du Nord. En 1998 en Israël, une importante épidémie a a été associée pour la première fois à une forte mortalité de la faune aviaire sauvage. Le virus (souche IS-98-ST1, lignage 1a) a été isolé du cerveau d’une cigogne moribonde. L’objet de cette thèse a été de construire un clone infectieux de la souche IS-98-ST1 afin d’en explorer les propriétés de neuroinvasion et de pouvoir mettre en évidence les déterminants moléculaires de sa virulence.Le virus obtenu à partir de la construction clone infectieux s’est révélé posséder les mêmes propriétés biologiques que le virus parental, que ce soit in vitro sur cellules Vero ou in vivo sur souris sensibles ou résistantes ou encore sur l’embryon de poulet. L’embryon de poulet est présenté ici comme un nouveau modèle d’évaluation de la virulence du VWN. Un modèle cellulaire neuronale (lignée de neuroblastomes humains, SK-N-SH) est aussi évalué dans ce manuscrit. En conclusion, un nouvel outil de génétique inverse a été obtenu pour le VWN. Cet outil permettra de travailler sur l’impact de mutations ponctuelles, ou de modifications plus importantes touchant un ou plusieurs gènes viraux sur la virulence du VWN, spécifiquement dans le contexte européenWest Nile virus (WNV) is a neurotropic virus mainly transmitted through mosquito bites. Wild birds represent the main reservoir hosts. Strains circulating in Europe belong to four lineages and have caused numerous but limited epidemics over the last few years. In 1998, an important outbreak associated to huge bird fatalities caused by a highly neuroinvasive strain (IS-98-ST1) took place in Israel. We aimed at producing a new infectious clone, based on the lineage 1a IS-98-ST1 WNV strain, for the characterization of its neuroinvasion properties as well as the molecular determinants of European WNV virulence. The growth kinetics of recombinant and parental WNV were similar in Vero cells. Moreover, the phenotypes of recombinant and parental WNV were indistinguishable in terms of viremia, viral load in the brain and mortality in susceptible and resistant mice. Finally, the pathobiology of the infectious clone was examined in embryonated chicken eggs, proposed as a new model for the evaluation of WNV virulence. The potential of human neuroblastoma cells (SK-N-SH) to discriminate between highly and mildly virulent WNV strains was assayed. In conclusion: a new molecular tool that is useful for the study of molecular determinants of WNV virulence has been generated. We take advantage of the high genetic stability of our one-piece infectious WNV cDNA clone to produce mutant viruses through the insertion of point mutations or the exchange of genetic fragments between WNV strains into the backbone of the IS-98-ST1 infectious clone
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Mohan, Swathi Groutas William C. "Potential inhibitors of dengue and West Nile virus proteases." Diss., The archival copy of this thesis can be found at SOAR (password protected), 2006. http://soar.wichita.edu/dspace/handle/10057/569.
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Thesis (M.S.)--Wichita State University, College of Liberal Arts and Sciences., Dept. of Chemistry."July 2006." Title from PDF title page (viewed on May 2, 2007). Thesis adviser: William C. Groutas. Includes bibliographic references (leaves 64-66).
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Debnath, Nitish Chandra. "Studies on defective interfering particles of West Nile virus." Thesis, University of Surrey, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305784.
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Ocampo, Diana Cruz. "Long-term Consequences of West Nile Virus in Virginia." VCU Scholars Compass, 2005. http://scholarscompass.vcu.edu/etd/1158.
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Objective: The purpose of this investigation was to describe the long-term effects and functional outcomes of patients in Virginia who were reported to the Virginia Department of Health with West Nile virus (WNV) non-neuroinvasive and neuroinvasive disease. The study identified the duration of symptoms after initial illness, the number of persons who fully recovered versus the number who continue to be symptomatic and how patients' quality of life differed after illness.Methods: The study population was drawn from 60 human cases that met the surveillance case definition for non-neuroinvasive and neuroinvasive WNV illness in Virginia between 2002-2004. Information was collected during personal interviews using a standard questionnaire. The questionnaire included questions on demographics, clinical signs and symptoms, existing medical conditions and the respondents' personal assessment of health. Statistical analysis were used to compare pre and post illness symptoms, respondents vs. non-respondents, and non-neuroinvasive respondents vs. neuroinvasive respondents. Results: Thirty-four patients were enrolled in the study. Five (14.7%) respondents had non-neuroinvasive disease and 29 (85.2%) had neuroinvasive disease. Thirty respondents (88.2%) reported being hospitalized. Respondents with non-neuroinvasive disease spent a median of 3.5 (range, 0-7) days in the hospital and were unable to resume normal activities for a median of 17 (range, 7-365) days. Respondents with neuroinvasive disease spent a median of 7.5 (range, 0-82) days in the hospital and were unable to resume normal activities for a median of 127.50 days (range, 0-1023). Two (40%) of the respondents that suffer from non-neuroinvasive illness were unable to resume normal activities for at least 90 days. Fifteen (51.7%) respondents with neuroinvasive disease were unable to resume normal activities for at least 90 days. At the time of the interview, 20% of respondents with non-neuroinvasive disease reported fatigue, tremors, arthralgia, paralysis and memory problems. Respondents with neuroinvasive disease reported fatigue (58.5%), weakness (51.7%), myalgias (37.9%), confusion (41.4%), and memory loss (55.2%). Conclusion: WNV illness, including non-neuroinvasive illness, may be more serious and prolonged than generally thought. Neuroinvasive disease resulted in long-term morbidity and non-neuroinvasive disease resulted in work absenteeism and extended recovery periods. The mortality rates and potential long-term effects associated with non-neuroinvasive and neuroinvasive illness emphasizes the importance of continuing to develop effective methods of targeting preventive education to high-risk populations while continuing to pursue longer-term solutions such as vaccines to prevent emerging infection. Further research is needed to document the long-term effects of WNV, especially in areas with a high number of WNV human cases with more non-neuroinvasive patients. WNV is an emerging infectious disease with a wide clinical spectrum and variable long-term effects; thus a public health concern.
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Bleas, Karine Alliot Anne. "Le virus West Nile un exemple d'arbovirus ré-émergent /." [S.l.] : [s.n.], 2003. http://theses.univ-nantes.fr/thesemed/PHbleas.pdf.
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Silenzi, Silvia <1984>. "Characterization of West Nile virus strains isolated in Italy." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/6759/1/Silenzi_Silvia_tesi.pdf.
Full textAbstract:
West Nile virus (WNV) is a neurotropic flavivirus that is maintained in an enzootic cycle between mosquitoes and birds, but can also infect and cause disease in humans and other vertebrate species. Most of WNV infections in humans are asymptomatic, but approximately 20% of infected people develop clinical symptoms, although severe neurological diseases are observed in less than 1% of them. WNV is the most widely distributed arbovirus in the world and has been recently associated with outbreaks of meningo-encephalitis in Europe, including Italy, caused by different viral strains belonging to distinct lineages 1 and 2. The hypothesis is that genetic divergence among viral strains currently circulating in Italy might reflect on their pathogenic potential and that the rapid spread of WNV with increased pathogenicity within naïve population suggest that epidemic forms of the virus may encode mechanisms to evade host immunity. Infection with WNV triggers a delayed host response that includes a delay in the production of interferon-α (IFN-α). IFNs are a family of immuno-modulatory cytokines that are produced in response to virus infection and serve as integral signal initiators of host intracellular defenses. The increased number of human cases and the lack of data about virulence of European WNV isolates highlight the importance to achieve a better knowledge on this emerging viral infection. In the present study, we investigate the phenotypic and IFN-α-regulatory properties of different WNV lineage 1 and 2 strains that are circulating in Europe/Italy in two cell lines: Vero and 1321N1. We demonstrate that: Vero and 1321N1 cells are capable of supporting WNV replication where different WNV strains show similar growth kinetics; WNV lineage 2 strain replicated in Vero and 1321N1 cells as efficiently as WNV lineage 1 strains; and both lineages 1 and 2 were highly susceptible to the antiviral actions of IFN-α.
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Silenzi, Silvia <1984>. "Characterization of West Nile virus strains isolated in Italy." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/6759/.
Full textAbstract:
West Nile virus (WNV) is a neurotropic flavivirus that is maintained in an enzootic cycle between mosquitoes and birds, but can also infect and cause disease in humans and other vertebrate species. Most of WNV infections in humans are asymptomatic, but approximately 20% of infected people develop clinical symptoms, although severe neurological diseases are observed in less than 1% of them. WNV is the most widely distributed arbovirus in the world and has been recently associated with outbreaks of meningo-encephalitis in Europe, including Italy, caused by different viral strains belonging to distinct lineages 1 and 2. The hypothesis is that genetic divergence among viral strains currently circulating in Italy might reflect on their pathogenic potential and that the rapid spread of WNV with increased pathogenicity within naïve population suggest that epidemic forms of the virus may encode mechanisms to evade host immunity. Infection with WNV triggers a delayed host response that includes a delay in the production of interferon-α (IFN-α). IFNs are a family of immuno-modulatory cytokines that are produced in response to virus infection and serve as integral signal initiators of host intracellular defenses. The increased number of human cases and the lack of data about virulence of European WNV isolates highlight the importance to achieve a better knowledge on this emerging viral infection. In the present study, we investigate the phenotypic and IFN-α-regulatory properties of different WNV lineage 1 and 2 strains that are circulating in Europe/Italy in two cell lines: Vero and 1321N1. We demonstrate that: Vero and 1321N1 cells are capable of supporting WNV replication where different WNV strains show similar growth kinetics; WNV lineage 2 strain replicated in Vero and 1321N1 cells as efficiently as WNV lineage 1 strains; and both lineages 1 and 2 were highly susceptible to the antiviral actions of IFN-α.
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Delker, Anna Maria. "Expression diagnostisch verwendbarer Antigene zum Nachweis West-Nil-Virus-spezifischer Antikörper." Doctoral thesis, Universitätsbibliothek Leipzig, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-138414.
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Grundlage der vorliegenden Arbeit ist die Überlegung, dass eine Möglichkeit, die Spezifität der bisher angewendeten Verfahren zur West-Nil-Virus-Diagnostik zu verbessern, in der Anwendung rekombinanter WNV-spezifischer Antigene besteht. Die unter anderem auf bioinformatischen Methoden basierende Identifikation von potenziellen B-Zell-Epitopen und Auswahl entsprechender Sequenzabschnitte richtete sich dabei gezielt auf immunogene Bereiche, die innerhalb der Gruppe der Flaviviren einen ausreichenden Sequenzunterschied zu allen weiteren sequenzverwandten Erregern, zusammengefasst im Japanische Enzephalitis-Serokomplex, boten. Drei ausgewählte Bereiche innerhalb der Strukturproteinsequenz, bezeichnet als prM, Cnat und Cme, sollten mit Hilfe des Expressionssystems Pichia pastoris bzw. Escherichia coli rekombinant exprimiert werden. Nach Erarbeitung optimaler Expressionsbedingungen folgte die affinitätschromatografische Reinigung der im weiteren Verlauf zur Immunisierung von Balb/c-Mäusen eingesetzten Polypeptide. Die gewonnenen Seren der nach verschiedenen Immunisierungsprotokollen geimpften Mäuse wurden im Anschluss immunologisch untersucht. Es zeigte sich, dass die rekombinanten Derivate des Capsid-Proteins eine deutliche Serokonversion hervorriefen. Analysen der mit Cnat und MBP-Cme immunisierten Mausseren wiesen vorhandene peptidspezifische sowie virusspezifische Antikörper nach. Der Einsatz dieser gewonnenen Peptidantigene im indirekten ELISA-Testsystem zur Detektion WNV-spezifischer Antikörper unter Verwendung humaner WNV-IgG-positiver Serumproben zeigte positive Resultate.
Im Gegensatz hierzu führte die Immunisierung mit prM lediglich zu einer unspezifischen murinen Antikörperbildung. Die Unterscheidung zwischen WNV-positiven und WNV negativen Humanseren war unter Verwendung des rekombinanten Antigens prM nicht möglich.
Im Ergebnis zeigten zwei der drei in dieser Arbeit rekombinant erstellten Strukturproteinabschnitte ihr immunologisches Potenzial in der Generierung muriner WNV spezifischer Antikörper. Zudem konnte mit der Expression der WNV-spezifischen C Protein Antigene ein Beitrag zur Etablierung eines indirekten ELISA-Testsystems zur Detektion WNV-bedingter Humaninfektionen geleistet werden.
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Wittich, Courtney Anne. "Spatial analysis of West Nile Virus and predictors of hyperendemicity in the Texas equine industry." Texas A&M University, 2007. http://hdl.handle.net/1969.1/85838.
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West Nile Virus (WNV) first appeared in Texas equids during June 2002. It has
since spread rapidly across the state and apparently become endemic. Data from
outbreaks occurring between 2002 and 2004 were analyzed to determine hotspots of
equine WNV disease, identify environmental factors associated with outbreaks, and to
create risk maps of locations with horses at a higher risk of the disease. Kriging was used
to model the smoothed WNV attack rates, and interpolated rates were mapped to describe
the spatial distribution of WNV disease risk in Texas. A retrospective time-space
analysis using a Poisson model was conducted on each year's data to identify clusters
with high attack rates. The resulting overlapping yearly clusters were considered areas of
hyperendemicity (hotspots). The counties identified as hotspots included Hockley,
Lubbock, and Lynn (primary cluster) and Leon and Roberstson (secondary cluster).
Environmental and geographic features were added to the disease maps and analyzed to
determine possible environmental factors associated with outbreaks. Locations in close
proximity to lakes, bird breeding routes, migratory flyway zones, crop farm and
agricultural land, and all dense vegetation were found to be important environmental predictors. Finally, risk maps were created that combined surveillance data on WNV
positive mosquito collections and wild bird WNV cases with previously identified
environmental risk factors to predict areas of high occurrence of WNV. These risk maps
could be used to implement various preventative measures to reduce the transmission of
WNV in the Texas equine industry.
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Petersen, Wade H. "Exploring mosquito diversity and dynamics across Washington State as they relate to West Nile virus transmission." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Summer2009/w_petersen_072009.pdf.
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Thesis (M.S. in entomology)--Washington State University, August 2009.Title from PDF title page (viewed on Aug. 12, 2009). "Department of Entomology." Includes bibliographical references (p. 65-68).
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Prell, Juliane. "Eine Studie zum Vorkommen des West-Nil-Virus in der Wildvogelpopulation Deutschlands." Doctoral thesis, Universitätsbibliothek Leipzig, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-127767.
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In den letzten Jahren erreichten viele neue (emerging) Viren Europa, die zum Teil (z.T.) zoonotisch auf den Menschen übertragbar sind. So musste man sich mit Geflügel- und Schweinegrippe, Blauzungenkrankheit, Infektiöser Anämie der Einhufer oder auch SARS (severe acute respiratory syndrome) auseinandersetzen. Bedingt durch verschiedene Faktoren, wie Klimawandel oder zunehmende Globalisierung und damit einhergehendem Verkehr zwischen den Kontinenten verbesserten sich auch die Bedingungen für die Virusverbreitung, so dass viele für Deutschland untypische Krankheitserreger auch hier auftraten. Das West-Nil-Virus (WNV) ist in Europa bereits endemisch verbreitet und könnte somit eine besondere Gefahr für Deutschland darstellen. Es ist ein bekannter Zoonose-Erreger, und sein Eintrag und die rasche Verbreitung des Virus in Amerika 1999 zeigten wie gefährlich neue Viren in naiven Populationen sein können. Über die Verbreitung des Virus in Deutschland gibt es nur wenige Studien z.B. des Robert-Koch-Instituts (LINKE et al. 2007a) und des Friedrich-Loeffler-Instituts (SEIDOWSKI et al. 2010), wobei in keiner Studie tote Vögel als Untersuchungsmaterial genutzt wurden. Da das WNV in Amerika mit einem auffälligen Vogelsterben einherging, ist es naheliegend, den Virusnachweis zuerst bei toten Vögeln zu erbringen.
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Francis, Stephen Starko. "West Nile virus in Nevada : mosquito infection rates and weather /." abstract and full text PDF (free order & download UNR users only), 2006. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1440921.
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Thesis (M.S.)--University of Nevada, Reno, 2006."December, 2006." Includes bibliographical references (leaves 29-33). Online version available on the World Wide Web. Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2006]. 1 microfilm reel ; 35 mm.
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Young, Joanne Alison. "The creation of an avian vaccine for West Nile virus." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/43511.
Full textAbstract:
West Nile Virus (WNV) arrived in North America in 1999 and has since caused significant morbidity and mortality, mainly in birds but also in horses and humans. Many families of birds, especially corvids, are highly susceptible to WNV, with infections often resulting in fatalities. Avian species susceptible to WNV infection also include endangered species, such as the Greater Sage-Grouse (Centrocercus uropbasianuts) and the Eastern Loggerhead Shrike (Lanius ludovicianus migrans). Although WNV is now endemic throughout the continent, to date there is no veterinary vaccine available for birds. This thesis focuses on the use of a recombinant adenovirus to construct vaccines against WNV, that would contain either the envelope or the NS3 ‘genes’ from WNV.
To assist in assessing the vaccines, work was undertaken to assess to what extent avian antibody reagents could be used in an avian species for which the antibody was not created. The duck specific CD8 antibody, Du-CD8-1 and the chicken/turkey specific CD4 antibody, CT4, bound to Japanese Quail T cells. The CD4 and CD8 antibody reagents were used to analyse Japanese quail T cell populations, establishing the proportions of CD4+ and CD8+ cells, and discovering a previously unreported population of CD4/CD8 double positive cells. An anti bird IgG antibody was found to bind to chicken, House Sparrow and Japanese Quail IgY; the anti-bird IgG antibody was able to detect IgY from these three species when used as part of a serum ELISA assay.
Results from initial vaccine testing in Japanese Quail (Coturnix japonica), indicated that the vaccines activated more T cells and triggered production of higher levels of antibodies in vaccinated birds compared to unvaccinated controls. This was achieved using an intracellular interferon gamma (IFN-γ) assay to assess T cell activation and a serum ELISA to measure levels of WNV specific antibodies. During a challenge assay, using a wild population of House sparrows (Passer domesticus) following infection with WNV, vaccinated birds showed overall reduced levels of viremia compared to unvaccinated controls.
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Munoz-Erazo, Luis Enrique. "Cellular Responses of the Retina to West Nile Virus Infection." Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/15404.
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Age-related macular degeneration (AMD) is the leading cause of blindness in the developing world in people aged over 60 years, manifested as a loss of central vision in one or both eyes, with significant morbidity including loss of mobility and depression. This condition involves the degeneration of the macula, and although the exact aetiology of this disease is unknown, various epidemiological studies have shown it to be multifactorial. Current research points towards the involvement of a dysregulated immune system in the pathogenesis and progression of the disease: as the body ages, the immune system increasingly adopts a more inflammatory basal state. However, not all of the aged population develops AMD and it is highly likely that an additional stimulus or stimuli is/are needed to exploit this dysregulated immune environment to initiate this disease. Given the range of pathogens that can infect the retina, we hypothesize that this breaking point could manifest as a chronic inflammation as a result of a low-level infection. West Nile Virus (WNV) is a flavivirus that has come into international prominence ever since its spread into previously WNV-free regions following the 1999 New York outbreak. As several case reports have shown that WNV is capable of infecting the retina, and given its immunopathogenic properties, we believe the virus is a useful tool to model key immune pathways and responses that may be involved in the development and progression of AMD. Of significant interest are the processes involved in the breakdown of the outer blood-retinal barrier (BRB), which is an important step in the progression of AMD from an early stage to a more severe one. Additionally, deciphering and understanding the profile and populations of leukocytes that are recruited during an immunopathic infection in an organ regarded as being immunoprivileged is of great appeal. With this in mind, we set out to investigate the effects of WNV infection on the retinal pigment epithelium (RPE), which comprises the outer BRB. Previously, our laboratory established the WNV BRB model by quantitating various parameters, such as level of infectivity, viral output by WNV-infected RPE and effects of WNV infection on RPE proliferation/migration. The effect of WNV on the extracellular matrix (ECM) production by RPE was also investigated and increases in collagen I, IV and fibronectin were noted. Global ECM production induced a lowered rate of proliferation of RPE seeded on WNV-infected RPE ECM as opposed to mock-infected ECM. A full genome microarray was also undertaken on WNV-infected RPE to analyse differentially regulated gene mRNA production, and increases in several immune genes, as well as genes involved in the stress-response pathway and the TGFβ pathway were found. This current investigation expanded upon these results, and found that WNV infection produces a predominantly CCL5 chemokine response rather than a CCL2 response. Additionally, a lack of TNF production was noted, despite a high initial upregulation of the TNF gene in WNV-infected cells. WNV attenuation was found to be predominantly IFNβ-1-driven, while induction of indoleamine 2,3 dioxygenase activity was induced in part by IFNλ-1 and -2. The effects of WNV infection on RPE barrier integrity was investigated, and an initial increase in infected cells of barrier integrity was observed. Several investigations resulted in a conclusion of a soluble-mediator as the likely mechanism behind this initial increase, and while none of the chemokines tested appeared to contribute to this change, the results suggest that it may be TLR3/RIG-I independent. Finally, establishment of a murine WNV intravitreal model was also undertaken, and several key parameters were determined, including confirmation of WNV-infection of the murine retina, effect of WNV titre on mortality, and histological analysis of the effects of WNV infection on the murine retina. Quantification of the leukocyte profile recruited into the WNV-infected murine retina and choroid revealed significant increases in inflammatory Ly6Chi monocytes, as well as significant differences between immune mice and naïve mice intravitreally infected with WNV, and differences between 2 month old and 5 month old mice. Collectively, these results highlight the importance of the interferon response in both direct and indirect anti-WNV activities and immunomodulation, the changes in outer BRB integrity and possible contributors to its degradation, and the establishment of the murine intravitreal WNV model along with identification of several key leukocytes that are recruited at the peak of infection. These results will help guide further research and highlight possible immune pathways that may contribute to dysregulated inflammatory processes that may occur during the pathogenesis of AMD.
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Hancock, Calvin. "Mosquitos associated with equine West Nile virus cases in southeastern Georgia." Click here to access dissertation, 2006. http://www.georgiasouthern.edu/etd/archive/fall2006/calvin_w_hancock/hancock_calvin_w_200608_ms.pdf.
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Thesis (M.S.)--Georgia Southern University, 2006."A dissertation submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science" ETD. Includes bibliographical references (p. 38-69)
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Pliego-Zamora, Adriana C. "The Antiviral Properties of Melaleuca alternifolia concentrate (MAC) against West Nile virus." Thesis, Griffith University, 2015. http://hdl.handle.net/10072/367888.
Full textAbstract:
Many Flaviviruses are mosquito-borne viruses that can causes disease in humans and animals including Dengue virus (DENV), West Nile virus (WNV), yellow fever virus (YFV), Japanese encephalitis virus (JEV) and tick-borne encephalitis virus (TBEV). These viruses are highly pathogenic to humans causing extensive morbidity and mortality and most importantly, their recent re-emergence and global spread is a current growing public health issue. Currently, DENV alone causes an approximate 50 million infection cases annually and WNV infections have been reported in the five continents. Despite the existence of licensed vaccines for YFV, JEV and TBEV, a major challenge remains given there are no specific and effective antiviral therapies against flaviviral infections.
Considering the homologies between flaviviral replication strategies, it may be possible to identify broad-spectrum compounds with both prophylactic and therapeutic activity against different flavivirus strains. Because the steps involved in compound discovery to their clinical use are protracted and expensive, studies should include testing existing clinically approved drugs as antivirals. Melaleuca alternifolia extracts are good candidates to be explored for novel uses as they have been extensively studied and their composition, chemistry, safety and toxicity are well documented. Melaleluca alternifolia concentrate (MAC) is obtained from the further purification of Tea Tree Oil (TTO) and is a new product exhibiting promising antimicrobial and anti-cancer activities.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Medical Science
Griffith Health
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Garcia-Tapia, David. "The role of macrophages and anti-viral antibodies in West Nile virus pathogenesis." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4475.
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Thesis (Ph. D.)--University of Missouri-Columbia, 2006.Title from title screen of research.pdf file (viewed on December 22, 2006) The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. "May 2006" Vita. Includes bibliographical references.
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Marshall, James S. "West Nile Virus in northern cardinals: antibody patterns and fitness consequences." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1157135336.
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Cozzie, Linsey Renee. "Anti-insect defensive behaviors of equines after West Nile virus infection." Click here to access thesis, 2007. http://www.georgiasouthern.edu/etd/archive/spring2007/linsey_r_cozzie/Cozzie_Linsey_R_200701_MS.pdf.
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Thesis (M.S.)--Georgia Southern University, 2007."A thesis submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science." Under the direction of William S. Irby. ETD. Electronic version approved: May 2007. Includes bibliographical references (p. 36-39)
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Eastwood, Gillian. "The potential ecology of West Nile virus in the Galápagos Islands." Thesis, University of Leeds, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.582086.
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The global increase in emerging infectious diseases [EID] over recent decades reinforces the need to understand epidemiological drivers of emergence, and the ecology of novel pathogens. Vector-borne pathogens can be a significant threat to biodiversity conservation as well as public health. Firstly I examine air-transportation as a mechanism for the dispersal of disease vectors to islands. I then investigate the risk posed by the mosquito- borne flavivirus West Nile virus [WNV] emerging to the Galapaqos Islands. The unprecedented spread of WNV through the Americas led to the decline of several USA bird populations and the introduction of WNV to Galapaqos could be catastrophic for endemic fauna there. Local data is required to predict WNV transmission dynamics and its ability to persist in Galapaqos should it reach the archipelago. Here I investigate the ecology (life history, population abundance and host-feeding patterns) of the Galapaqos mosquitoes Culex quinquefasciatus and Aedes taeniorhynchus and determine their vector competence for WNV. I found that, although limited in distributional abundance by extreme temperatures and salt intolerance, virus competent Cx. quinquefasciatus has feeding behaviour consistent with a role as a WNV 'bridge vector'. Aedes taeniorhynchus is widespread and abundant in Galapaqos and a highly competent WNV vector (unlike US strains of the mosquito), however evidence of avian feeding is lacking. The susceptibility of vertebrate hosts in Galapaqos and their ability to amplify WNV remains to be tested directly. During surveillance conducted in Galapaqos and mainland Ecuador, I did not detect evidence of WNV infection. Nevertheless, pathogen invasion is a dynamic system and continued surveillance is required to ensure early detection. Risk assessments help to identify strategies to mitigate the impact of EIDs. The WNV threat calls for stringent biosecurity in Galapaqos and local capacity for vector control which can be implemented as an emergency response to WNV introduction.
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Jourdain, Elsa. "Oiseaux sauvages et virus West Nile : étude éco-épidémiologique en Camargue." Phd thesis, Université Joseph Fourier (Grenoble), 2006. http://tel.archives-ouvertes.fr/tel-00144110.
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Le travail présenté ici s'intéresse au rôle des oiseaux sauvages dans l'épidémiologie du virus West Nile (WN) en Camargue. Des espèces d'oiseaux susceptibles d'intervenir dans les différentes phases de circulation du virus (introduction, amplification, dispersion, émergence) sont identifiées en s'appuyant sur les données bibliographiques relatives à la maladie et sur des critères ornithologiques. Les investigations épidémiologiques effectuées pour quelques unes de ces espèces en 2004 (année épizootique) et en 2005 (année post-épizootique) montrent que le virus WN circule dans la population d'oiseaux de Camargue. Pour les oiseaux migrateurs arrivant d'Afrique au printemps, les dates et lieux de ces contacts restent inconnus. Concernant les oiseaux sédentaires, deux isolats d'une même souche virale ont été obtenus en 2004, réciproquement à partir du cerveau d'une Pie bavarde Pica pica et d'un Moineau domestique Passer domesticus, et totalement séquencés. L'étude phylogénétique de cette souche montre qu'elle appartient au même cluster que celles précédemment isolées en Europe méditerranéenne. Les résultats sérologiques et virologiques chez ces deux espèces d'oiseaux, souvent observées à proximité des écuries, en font des candidates à l'amplification et l'émergence du virus WN chez les chevaux de Camargue. La mise en évidence, en 2005, d'ARN viral dans les fientes d'une Pie bavarde conforte cette hypothèse. Les recherches doivent se poursuivre pour évaluer la part respective des différents oiseaux de Camargue dans la circulation du virus WN en utilisant d'autres approches, comme par exemple l'analyse des repas de sang des moustiques vecteurs, récemment identifiés.
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Brochu, Elizabeth A. "Mosquito Abundance and West Nile Virus in Cuyahoga County, 2005 - 2016." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1515138053914272.
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Kala, Abhishek K. "Spatially Explicit Modeling of West Nile Virus Risk Using Environmental Data." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc822841/.
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West Nile virus (WNV) is an emerging infectious disease that has widespread implications for public health practitioners across the world. Within a few years of its arrival in the United States the virus had spread across the North American continent. This research focuses on the development of a spatially explicit GIS-based predictive epidemiological model based on suitable environmental factors. We examined eleven commonly mapped environmental factors using both ordinary least squares regression (OLS) and geographically weighted regression (GWR). The GWR model was utilized to ascertain the impact of environmental factors on WNV risk patterns without the confounding effects of spatial non-stationarity that exist between place and health. It identifies the important underlying environmental factors related to suitable mosquito habitat conditions to make meaningful and spatially explicit predictions. Our model represents a multi-criteria decision analysis approach to create disease risk maps under data sparse situations. The best fitting model with an adjusted R2 of 0.71 revealed a strong association between WNV infection risk and a subset of environmental risk factors including road density, stream density, and land surface temperature. This research also postulates that understanding the underlying place characteristics and population composition for the occurrence of WNV infection is important for mitigating future outbreaks. While many spatial and aspatial models have attempted to predict the risk of WNV transmission, efforts to link these factors within a GIS framework are limited. One of the major challenges for such integration is the high dimensionality and large volumes typically associated with such models and data. This research uses a spatially explicit, multivariate geovisualization framework to integrate an environmental model of mosquito habitat with human risk factors derived from socio-economic and demographic variables. Our results show that such an integrated approach facilitates the exploratory analysis of complex data and supports reasoning about the underlying spatial processes that result in differential risks for WNV. This research provides different tools and techniques for predicting the WNV epidemic and provides more insights into targeting specific areas for controlling WNV outbreaks.
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Vittecoq, Marion. "Maladies infectieuses émergentes au sein des zones humides méditerranéennes dans le contexte des changements globaux." Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20269/document.
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L'émergence de maladies telles que le SRAS et le SIDA au cours des dernières décennies a fait prendre conscience des liens étroits existant entre santé animale, santé humaine et santé des écosystèmes. En effet, les pathogènes émergents ont pour la plupart une origine zoonotique (i.e. ils circulaient à l'origine au sein des populations animales). Les risques sanitaires associés à ces émergences sont en constante évolution sous l'influence des changements globaux qui modifient les écosystèmes et les contacts entre les hôtes. La prévention et le contrôle des maladies infectieuses émergentes nécessitent la compréhension de leur dynamique dans l'ensemble des compartiments dans lesquels elles circulent. Le travail présenté ici avait pour objectif d'améliorer cette compréhension au sein des zones humides méditerranéennes en ce concentrant sur deux pathogènes émergents : les virus Influenza A (VIA) et le virus West Nile. Il a été structuré selon trois axes de recherche : i) Utiliser la surveillance épidémiologique de l'avifaune sauvage pour comprendre la circulation du virus West Nile dans le bassin méditerranéen ii) Comprendre la dynamique des VIA au sein des différents compartiments où ils circulent et à leur interface iii) Comprendre le rôle des conditions environnementales dans la dynamique des VIA notamment au sein des populations humaines. Nos résultats mettent en évidence l'intérêt de mener des études multidisciplinaires sur le long terme pour comprendre l'épidémiologie des maladies émergentes. Ils soulignent également le rôle des activités anthropiques et des conditions environnementales dans la dynamique de ces maladies. Nos études apportent des éléments de réflexion pour allier gestion des risques d'émergence et gestion des écosystèmes et des populations. Elles encouragent à développer ce type d'approche afin de relever le défi de la prévention et du contrôle des pathogènes émergentsDuring the last decades, the emergence of numerous infectious diseases such as SARS and AIDS has raised awareness of the close links that exist between animal health, human health and ecosystem health. Many of the emerging pathogens have a zoonotic origin (i.e. they originally circulated among animal populations). The health risks associated with the emergence of these diseases are progressing under the influence of global changes that affect ecosystems and contacts between hosts. The prevention and control of emerging infectious diseases require an in-depth understanding of their dynamics in all the compartments in which they occur. The aim of the present work is to improve our understanding of these phenomena within the context of Mediterranean wetlands by focusing on two emerging pathogens: Influenza A viruses (IAV) and West Nile virus. The thesis is structured around three research axes i) Using epidemiological surveillance of wild birds to investigate the circulation of West Nile virus in the Mediterranean Basin ii) Exploring IAV dynamics in the different compartments in which they circulate and at their interface iii) Determining the role of environmental conditions in IAV dynamics, especially within human populations. Our results highlight the value of long-term interdisciplinary studies for the understanding of the epidemiology of emerging diseases. They also emphasize the role of human activities and environmental conditions in the dynamics of these diseases. Our studies open up perspectives for combining emerging disease risk management and the management of ecosystems and populations. They also argue in favour of further developing this type of approach in order to meet the challenge of emerging pathogen prevention and control
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Osório, Hugo Costa. "West nile virus in Portugal: vector population, host interaction and detection of new flaviviruses." Doctoral thesis, Universidade de Évora, 2013. http://hdl.handle.net/10174/9043.
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This thesis describes the studies undertaken in the epidemiology of West Nile virus (WNV) in Portugal exploring several key components of its natural cycle: identification of mosquito vector-populations – geographical and seasonal distribution; analysis of genetic and environmental determinants on feeding patterns of mosquito vectors; experimental transmission of WNV; identification of flaviviruses detected in wild mosquitoes; serological survey of wild birds potentially involved in the epizootic cycle of WNV; finally, a description of a clinical human case of WNV infection reported in 2010.
Culex pipiens was one of the most abundant mosquito species demonstrating ecological and intrinsic competence to transmit WNV. No positive mosquito pools for WNV were detected, but new mosquito-only flaviviruses were identified. The presence of antibodies anti-WNV in a juvenile turtle-dove suggests local virus circulation.
In conclusion, Portugal meets suitable conditions for epizootic circulation of WNV and for the occurrence of accidental human infections; RESUMO
O vírus West Nile em Portugal
Vetores, interação com hospedeiros e deteção de novos flavivírus
Esta tese descreve os estudos desenvolvidos na epidemiologia do vírus West Nile (VWN) em Portugal explorando várias componentes do seu ciclo natural: identificação das populações de mosquitos vetores – distribuição geográfica/ sazonal; análise de determinantes genéticos/ ambientais na preferência de hospedeiro de mosquitos vetores; transmissão experimental do VWN; identificação de flavivírus detectados em mosquitos selvagens; estudo serológico em aves potencialmente reservatórios do vírus; finalmente é descrito um caso clínico humano de infecção por VWN detetado em 2010.
Culex pipiens foi uma das espécies de mosquito mais abundantes e demonstrou competência ecológica e intrínseca para transmitir o VWN. Não foram detectados pools de mosquitos positivos para o VWN, mas foram identificados novos flavivírus específicos de insetos. A presença de anticorpos anti-WNV numa rola juvenil sugere circulação local do vírus.
Em conclusão, Portugal reúne condições adequadas para a circulação epizoótica do VWN e para a ocorrência de infecções humanas acidentais.
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Davis, William G. "Protein binding sites and cis-acting sequences on the West Nile Virus 3' (+) SL RNA." unrestricted, 2007. http://etd.gsu.edu/theses/available/etd-07262007-134423/.
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Thesis (Ph. D.)--Georgia State University, 2007.Title from file title page. Margo Brinton, committee chair; W. David Wilson, Teryl Frey, committee members. Electronic text (120 p. : ill. (some col.)) : digital, PDF file. Description based on contents viewed Nov. 20, 2008. Includes bibliographical references.
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Bakli, Mahfoud. "Marqueurs d'exposition aux piqûres de moustiques du genre Culex et processus physiopathologiques d'infection au virus de West Nile." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM5056/document.
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Le virus West Nile,WNV est responsable de milliers de cas de morbidité et de mortalité chez les oiseaux, les chevaux et l’homme. Le WNV se transmet par des moustiques du genre Culex. Les méthodes entomologiques ne permettent pas l’évaluation individuelle directe du contact hôte/vecteur. 5 protéines salivaires de Culex ont été sélectionnées, produites, et évaluées comme des candidats antigéniques de l'exposition aux piqûres de Culex. Des sérums humains du sud de France exposés à des densités de Culex distinctes et des sérums de chevaux exposés à l'infection par le WNV ont été testés. Une protéine 30kD est reconnue par les chevaux exposés à Culex. Cependant, pas de différence de réponse d’anticorps n’a été observée entre les animaux faiblement et fortement exposés. Concernant les processus physiopathologiques de la maladie causée par le WNV, la cinétique des profils d'expression de protéines de l’hôte dans le cerveau de souris infectées par le WNV, a été étudiée sur des échantillons prélevés avant et après l’apparition des signes cliniques, en utilisant 2D-DIGE et iTRAQ. 148 protéines différentiellement exprimées. Les voies de signalisation altérées au cours de l'infection précoce et tardive ont été identifiées. Les profils protéiques de LCR de patients atteints de WNND et des individus témoins ont été comparés, en utilisant l’approche iTRAQ. 47 protéines ont été trouvées différemment exprimées chez les patients WNND. Un candidat potentiel biomarqueur, la Defensine-alpha1, a été évalué par ELISA sur des échantillons humains de LCR/sérum. Les biomarqueurs putatifs identifiés dans cette étude peuvent être un outil précieux d’évaluation de la mesure de la gravité du WNVWest Nile Virus,WNV is responsible for thousands of cases of morbidity and mortality in birds, horses and humans. WNV is transmitted mainly by mosquitoes by Culex species, to avian hosts. Entomological methods did not give direct individual evaluation of the host/vector contact. 5 salivary proteins from the Culex genus were selected for a production under recombinant forms for further evaluation as potential antigenic candidates of exposure to Culex bites. Sera from individuals living in south of France exposed to distinct Culex density and sera from horses exposed to WNV infection were tested. The recombinant protein30 kDa was recognized only by horses exposed to Culex. However, no difference of antibody response between low and high exposed to Culex. Concerning the pathophysiological processes of WNV disease, a kinetics host brain protein expression profiles of WNV-infected mice using samples collected prior and after clinical signs apparition was performed using proteomic approaches 2D-DIGE and iTRAQ. 148 distinct proteins was found altered following WNV infections. The functional signaling networks in samples collected during early and late infection have been identified. Un examination of CSF protein profiles between patients with neuroinvasive disease (WNND) and control individuals was performed using iTRAQ approach. 47 proteins were found differentially expressed in WNND patients compared to controls. A potential biomarker candidates, defensin-alpha1 was assessed by ELISA using other human paired CSF/serum samples. The putative biomarker identified in this study may potentially be a valuable tool in the assessment of the extent of WNV severity
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Elbahesh, Husni. "Functional Analysis of the Murine Oligoadenylate Synthetase 1b (Oas1b)." Digital Archive @ GSU, 2006. http://digitalarchive.gsu.edu/biology_theses/3.
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The flavivirus resistance gene, Flv, in mice has been identified as 2'-5' oligoadenylate synthetase 1b (Oas1b). Susceptible mice produce a protein that is truncated (Oas1btr) at the C-terminus due to a premature stop codon encoded by a C820T transition. Mice produce 8 Oas1 proteins, Oas1a-Oas1h. In the present study, Oas1a, Oas1b and Oas1btr were expressed as MBP-fusion proteins in bacteria and purified. 2-5A synthetase activity was demonstrated using MBP-Oas1a, while neither MBP-Oas1b nor MBP-Oas1btr were functionally active. The 2-5A synthetase activity of MBP-Oas1a was inhibited in a dose-dependent manner by the addition of MBP-Oas1b but not MBPOas1btr. Finally, three RNA probes were synthesized from the 3' end of the WNV Eg101 genome and used to test the ability of the expressed Oas1 proteins to bind to viral RNA. Results of the RNA binding activity assays suggest Oas1 proteins may specifically interact with regions of WNV RNA.
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Mallya, Shruti. "Modelling Human Risk of West Nile Virus Using Surveillance and Environmental Data." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35734.
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Limited research has been performed in Ontario to ascertain risk factors for West Nile Virus (WNV) and to develop a unified risk prediction strategy. The aim of the current body of work was to use spatio-temporal modelling in conjunction with surveillance and environmental data to determine which pre-WNV season factors could forecast a high risk season and to explore how well mosquito surveillance data could predict human cases in space and time during the WNV season. Generalized linear mixed modelling found that mean minimum monthly temperature variables and annual WNV-positive mosquito pools were most significantly predictive of number of human WNV cases (p<0.001). Spatio-temporal cluster analysis found that positive mosquito pool clusters could predict human case clusters up to one month in advance. These results demonstrate the usefulness of mosquito surveillance data as well as publicly available climate data for assessing risk and informing public health practice.
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Zheng, Hui. "Evaluation and Analysis of the Canadian Surveillance System for West Nile Virus." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23239.
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West Nile virus (WNv) is an arbovirus and is transmitted by infected mosquitoes after feeding on the blood of birds carrying the virus. The Canadian WNv national surveillance system has just completed its tenth year of operation. The thesis is to evaluate the surveillance system and analyze multi-year human data. The evaluation includes the use of multiple lines of complementary methods such as the US CDC surveillance guidelines, Canadian Evaluation Framework, document review and a survey. Logistic and Poisson regressions were used for data analyses. WNv has become endemic in most parts of Canada since the virus occurred in 2001. The virus activity is peak around August. High numbers of human cases with WNv neurological syndrome identified pose a significant health concern due to the long term sequelae among affected patients. WNv national surveillance met its main objectives and there is a continual need for the surveillance.
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Elbahesh, Husni M. "Study of Innate Immune Response Components in West Nile Virus Infected Cells." Digital Archive @ GSU, 2011. http://digitalarchive.gsu.edu/biology_diss/94.
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Two cellular innate responses, the dsRNA protein kinase (PKR) pathway and the 2'-5' oligoadenylate synthetase (OAS)/RNase L pathway, are activated by dsRNAs produced by viruses and reduce translation of host and viral mRNAs. PKR activation results in eIF2a phosphorylation. As a consequence of eIF2a phosphorylation, stress granules (SGs) are formed by the aggregation of stalled SG proteins with pre-initiation complexes and mRNA. West Nile virus (WNV) infections do not induce eIF2a phosphorylation despite upregulation of PKR mRNA and protein suggesting an active suppression of PKR activation. Assessment of the mechanism of suppression of PKR activation in WNV-infected cells indicated that WNV infections do not induce PKR phosphorylation so that active suppression is not required.
In contrast to infections with "natural" strains of WNV, infections with the chimeric W956 infectious clone (IC) virus efficiently induce SGs in infected cells. After two serial passages, the IC virus generated a mutant (IC-P) that does not induce SGs efficiently but does induce the formation of NS3 granules that persist throughout the infection. This mutant was characterized.
2'-5' oligoadenylate synthetases (OAS) are activated by viral dsRNA to produce 2-5A oligos that activate RNase L to digest viral and cellular RNAs. Resistance to flavivirus-induced disease in mice is conferred by the full-length 2'-5' oligoadenylate synthetase 1b (Oas1b) protein. Oas1b is an inactive synthetase that is able to suppress the in vitro synthetase activity of the active synthetase Oas1a. The ability of Oas1b to inhibit Oas1a synthetase activity in vivo and to form a heteromeric complex with Oas1a was investigated. Oas1b suppressed 2-5A production in vivo. Oas1a and Oas1b overexpressed in mammalian cells co-immunoprecipitated indicating the formation of heteromeric complexes by these proteins.
Unlike mice, humans encode a single OAS1 gene that generates alternatively spliced transcripts encoding different isoforms. Synthetase activity has previously been reported for only three of the isoforms. The in vitro synthetase activity of additional OAS1 isoforms was analyzed. All tested isoforms synthesized higher order 2-5A oligos. However, p44A only produced 2-5A dimers which inhibit RNase L.
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Boos, Sarah Bryant. "A Spatial Analysis of Demographic Factors of West Nile Virus in Georgia." Digital Archive @ GSU, 2009. http://digitalarchive.gsu.edu/iph_theses/68.
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Background: West Nile Virus (WNV) is a serious mosquito-borne disease that can potentially lead to death. The purpose of this study is to spatially examine known risk factors for WNV within Georgia at the county level. The study produces maps that relate known WNV cases to high, medium, and low risk factor areas for additional analyses. Methodology: Cartographic visualization and statistical analysis software was used to examine the relationships between: the geographical distribution of age, race, gender, urbanicity, and population density of Georgians in relation to WNV cases by county. Chi-square analysis and odds rations were calculated to determine whether or not associations of risk and the likelihood of WNV case reports were significant. Results: Gender was found to be significantly associated with the distribution of reported WNV cases. Identification of high risk areas throughout the state was determined through the use of Geographic Information System software. Conclusion: Insights into the visual distribution of WNV risk factors throughout the state of Georgia can assist policy makers and public health planners to optimize resources in WNV transmission and prevention abatement and education efforts. This exploratory study provides a critical first glimpse into the distribution of WNV risk factors throughout the state.
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Pulit-Penaloza, Joanna A. "Regulation of Interferon Stimulated Genes in West Nile Virus Infected Mouse Embryofibroblasts." Digital Archive @ GSU, 2012. http://digitalarchive.gsu.edu/biology_diss/110.
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The induction of type I interferon (IFN) and subsequent activation of interferon stimulated genes (ISGs) represent a first line of defense against viral infection. Typically type I IFN signaling leads to the phosphorylation of the STAT1 and STAT2 transcription factors (TFs) which then form a trimetric complex with IRF-9 and translocate to the nucleus to induce ISG expression. However, the results of this study showed that IFN-mediated upregulation of the ISG Oas1b, the product of which confers resistance to flavivirus induced disease, can be induced in a STAT1-independent manner. Since numerous ISGs have antiviral functions, many viruses have evolved strategies to disrupt the type I IFN-signaling pathway. In cases when STAT1 activation is blocked by a viral infection, STAT1-independent upregulation of ISGs provides an additional strategy for the cell to mount an effective antiviral response. Infection of mouse embryofibroblasts (MEFs) with West Nile virus (WNV) induced the production of IFN beta and STAT1 and STAT2 phosphorylation but blocked nuclear translocation and binding of these TFs to the promoters of the ISGs, Oas1a, Oas1a, Irf7 and Irf1. However, each of these antiviral ISGs was efficiently upregulated in infected cells and IRF-9 was shown to be crucial for the upregulation of Oas1a, Oas1b and Irf-7. IRF-3 or IRF-7 was needed to maintain the upregulation of these genes at later times of infection. In contrast, the upregulation of Irf1 by WNV infection did not depend on the tested IRFs but was reduced by inhibition of the p38 or NF-kappa B pathways. Although Irf1 mRNA was efficiently upregulated in WNV-infected cells IRF-1 protein synthesis was blocked. The precise mechanism of the IRF-1 translational suppression is not yet known, but the suppression was shown not to be due to increased proteasomal degradation of IRF-1 nor to alternative splicing of Irf1 mRNA. Preliminary results suggest miRNAs may play an indirect role in regulating IRF-1 translation.
The results of this study expand knowledge about the strategies evolved by viruses to evade host cell antiviral responses and also provide valuable insights about alternative mechanisms utilized by the host cell to counteract viral infections.
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Condotta, Stephanie Anne. "Molecular and cellular studies of the West Nile virus NS2B/NS3 protease." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/26994.
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West Nile virus (WNV) is the most widely distributed arthropod-borne virus globally. It can cause a potentially fatal infection and has become a public health concern in North America since its introduction in 1999. Currently, there are no vaccines or treatments available for human WNV infections. As such, it is important to understand the virus life cycle, in order to develop effective therapeutics. The WNV protease heterocomplex, NS2B/NS3, is a prime target for antiviral therapy and has become the focus of much research. It is important to understand protease function first, in order to develop effective inhibitors. The overall goal of this thesis was to gain a better understanding into the function of the full-length NS2B/NS3 protease heterocomplex within the intracellular microenvironment. I hypothesized that there are critical residues essential for the interaction between NS2B and NS3 that affect protease activity and protein stability. The first aim of this project was to generate a cell-based fluorescent substrate assay to investigate the protease activity of the full-length NS2B/NS3 protease heterocomplex within the cell. My results demonstrate that the full-length NS2B/NS3 protease heterocomplex functions differently within the context of the cell, compared to what has been previously observed in vitro (Chapter 2). In the second aim, I investigated NS2B function on NS3 protease cis-cleavage and trans-cleavage activity. My results reveal an important dual role the NS2B protein plays in the proper function of the full-length NS2B/NS3 protease heterocomplex (Chapter 3). In the third aim, I utilized the information gathered to rationally design and test a serine protease inhibitor directed against the full-length NS2B/NS3 protease heterocomplex (Chapter 4). Taken together, my results highlight the importance of utilizing cell-based assays to assess protease activity, as this allows for the investigation of NS2B/NS3 protease function in a more physiologically relevant environment. The results presented in this thesis further our understanding of the activity of the full-length WNV NS2B/NS3 protease heterocomplex within the context of the cell. The information gathered gives insight into the regulation of viral protease function that could be utilized in the rational drug design towards the WNV NS2B/NS3 protease heterocomplex.
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Beebe, Taylor A. "A two host species stage-structured model of West Nile virus transmission." VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4225.
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We develop and evaluate a novel host-vector model of West Nile virus (WNV) transmission that incorporates multiple avian host species and host stage-structure (juvenile and adult stages), with both species-specific and stage-specific biting rates of vectors on hosts. We use this model to explore WNV transmission dynamics that occur between vectors and multiple structured host populations as a result of heterogeneous biting rates. Our analysis shows that increased exposure of juvenile hosts results in earlier, more intense WNV transmission when compared to the effects of differential host species exposure, regardless of other parameter values. We also find that, in addition to competence, increased juvenile exposure is an important mechanism for determining the effect of species diversity on the disease risk of a community.
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Elwell, Gretchen E. "Spatial analysis of West Nile virus in Colorado, using geographical information systems." Diss., Online access via UMI:, 2006.
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Gibson, Tiffany C. M. "The seasonality of parasites in Illinois house sparrows (Passer domesticus) : effect of stress on infection parameters /." View online, 2010. http://repository.eiu.edu/theses/docs/32211131524730.pdf.
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Adiji, Olubu Adeoye. "Presence of Wolbachia, A Potential Biocontrol Agent: Screening for Vertebrate Blood Meal Source and West Nile Virus in Mosquitoes in the North Texas Region." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc862878/.
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West Nile virus (WNV) is a geographically endemic mosquito-borne flavivirus that has spread across the United States infecting birds, mosquitos, humans, horses and other mammals. The wide spread nature of this virus is due to the ability of the mosquito vector to persist in broad, ecological diverse environments across the United States. In this study, mosquito populations in North Texas region were sampled for detection of Wolbachia, blood meal source, and WNV. The ultimate goal of this study was to examine the potential of a biocontrol agent, Wolbachia sp. that colonizes the hindgut of various insects, including mosquitos, as a natural means to interrupt virus transmission from mosquitos to other hosts, including humans. In Australia, Wolbachia sp. from fruit flies (Drosophila melanogaster) have been successfully used to block transmission of a similar pathogenic virus from mosquitos responsible for transmission of Dengue fever.
Here, mosquitoes were collected using CDC style Gravid Traps in Denton, Texas, from October 2012 through September 2014. Collected mosquitoes were identified, sexed, and categorized as to the amount of host blood in their alimentary system using a Zeiss Axio Zoom microscope (Carl Zeiss Microscopy, LLC, Thornwood, NY). Culex quinquefaciatus was the dominant blood engorged species collected. Smaller populations of Culex tarsalis and Aedes albopictus, another known vector for WNV were also collected. Mosquito larva were also collected from the UNT water research field station and reared to adults. Cx. tarsalis was the dominant mosquito taken from this habitat.
Samples of Cx. quinquefasciatus, Cx. tarsalis and A. albopictus were analyzed for Wolbachia sp. and to identify host blood in the mosquito alimentary system. Total DNA extraction from the pool of mosquito samples was by both commercially available DNA extraction kits (Qiagen, Valencia, CA) and salt extraction technique. Polymerase chain reaction (PCR) was used to amplify and identify Wolbachia sp. 16SrDNA and mitochondrial DNA from vertebrate blood. The maternally inherited endosymbiont, Wolbachia, were found to be uniformly distributed across the mosquitoes sampled in this study. Blood meal analysis by PCR showed that Cx. quinquefaciatus fed more on birds than on mammalian blood sources based on the previously developed primers used in this study.