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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Detection of nonstructural protein NSm1 in Rift Valley Fever Virus virions assembled in insect but not mammalian cells

McGreevy, Alan 07 January 2013 (has links)
Rift Valley fever virus is a zoonotic pathogen that is transmitted between mosquitoes and mammals such as sheep, cattle and humans. It is an enveloped negative-sense single-stranded RNA virus, which is a member of the family Bunyaviridae and the genus Phlebovirus. During replication, RVFV produces a 78 kDa glycoprotein NSm1 of unknown function, believed to be nonstructural. Here I show that NSm1 is incorporated into RVFV virions assembled in C6/36 mosquito cells, but not in virions assembled in Vero E6 mammalian cells. The presence of NSm1 in insect-amplified virions was demonstrated through repeated immunoblots of purified virions and further supported by mass spectrophotometric confirmation of the identity of immunoblot-positive protein bands. This research appears to be the first evidence that distinct viral protein profiles are correlated to the host cell in which replication occurred.
2

Detection of nonstructural protein NSm1 in Rift Valley Fever Virus virions assembled in insect but not mammalian cells

McGreevy, Alan 07 January 2013 (has links)
Rift Valley fever virus is a zoonotic pathogen that is transmitted between mosquitoes and mammals such as sheep, cattle and humans. It is an enveloped negative-sense single-stranded RNA virus, which is a member of the family Bunyaviridae and the genus Phlebovirus. During replication, RVFV produces a 78 kDa glycoprotein NSm1 of unknown function, believed to be nonstructural. Here I show that NSm1 is incorporated into RVFV virions assembled in C6/36 mosquito cells, but not in virions assembled in Vero E6 mammalian cells. The presence of NSm1 in insect-amplified virions was demonstrated through repeated immunoblots of purified virions and further supported by mass spectrophotometric confirmation of the identity of immunoblot-positive protein bands. This research appears to be the first evidence that distinct viral protein profiles are correlated to the host cell in which replication occurred.
3

Développement d'un support microfluidique papier pour le diagnostic bas coût d'arboviroses émergentes / Development of a paper-based microfluidic support for the low-cost diagnosis of emerging arboviroses

Theillet, Gérald 07 December 2018 (has links)
L'incidence des infections à arbovirus (arthropod born virus) a augmenté de façon spectaculaire au cours des dernières décennies dans les régions tropicales et subtropicales du globe. Les virus de la dengue et du chikungunya sont transmis par les moustiques du genre Aedes et peuvent causer un large panel de symptômes, allant parfois jusqu’au décès. Bien que les tests de diagnostic conventionnels fournissent un diagnostic, l'accès à ces tests est limité dans les pays en développement. Un diagnostic précoce et rapide est crucial pour améliorer la prise en charge du patient. Il y a un besoin urgent de développer des outils peu chers, simples d’utilisation, rapides, et utilisables auprès du patient.Un PAD imprimé à la cire a été développé et évalué pour la détection de la protéine Non Structurale 1 (NS1) de la dengue, dans du sang et du plasma. Le PAD a été en mesure de détecter spécifiquement 10 ng.mL-1 de protéines dans divers types d'échantillons, en 6 à 8 minutes. Par la suite, une version améliorée du PAD obtenue par découpe laser a été conçue et testée pour la détection de la protéine NS1 de la dengue et des IgM spécifiques du virus, dans le sang et le plasma. Ces deux paramètres ont pu être détectés en 8 minutes. Les travaux de mise au point du PAD effectués sur la dengue ont ensuite été appliqués à la détection des IgM du virus du chikungunya dans des sérums humains, en utilisant des Particules virales Pseudotypées (PPs). Les résultats obtenus ont montré une sensibilité de 70,6% et une spécificité d'environ 98%. Le PAD a montré peu de réactions croisées avec d'autres arboviroses. Les PPs ont enfin été caractérisées par différentes méthodes physico-chimiques. / The incidence of arboviruses infections has increased dramatically in recent decades in tropical and sub-tropical areas worldwide. Dengue and chikungunya viruses are typically transmitted by mosquitoes and can cause a wide range of symptoms, and sometimes death. Although conventional diagnostic tests can provide diagnosis of acute infections, access to these tests is often limited in developing countries. Early and prompt diagnosis is crucial to improve patient management. Consequently, there is an urgent need to develop affordable, simple, rapid, and robust tools that can be used at ‘Point of Care’ settings.We developed and evaluated a PAD for the detection of the dengue Non Structural 1 (NS1) viral protein in blood and plasma samples. The PAD was able to detect specifically 10 ng.mL-1 of NS1 protein in various sample types and in 6-8 minutes. Secondly, an improved version of the PAD obtained by laser cutting was designed and tested for the detection of dengue NS1 protein and virus-specific IgM in blood and plasma. Each parameter could be detected in 8 minutes. PAD development performed on dengue fever was then applied to the detection of chikungunya virus IgM in human sera, using viral Pseudo-Particles (PPs). These synthetic antigens have proven to be powerful tools for specific IgM detection. The results obtained showed a sensitivity of 70.6% and a specificity of approximately 98% with a time to results of less than 10 minutes. The PAD showed few cross reactions with other arbovirusess. The PPS were finally characterized with different physico-chemical methods in order to determine the key factors of their performances.
4

Le virus Chikungunya : mécanismes évolutifs et outils de génétique inverse / The Chikungunya virus : evolutionnary mechanisms and reverse genetic methods

Mohamed Ali, Souand 20 December 2017 (has links)
L’émergence de certains arbovirus pathogènes pose un problème majeur en termes de santé public. Le virus Chikungunya (CHIKV) est un exemple de virus émergent car il s’est récemment adapté à un nouveau vecteur et cause des épidémies explosives. Cette émergence est en partie la conséquence de phénomènes liés à la grande plasticité génomique du CHIKV. Mieux comprendre les mécanismes d’adaptation des arbovirus pourrait permettre de mieux contrôler ces pathogènes viraux. La première partie de cette thèse porte sur l’étude des mutations associées à l’évolution à long terme du CHIKV sur différentes lignées de mammifères et de moustiques. Les résultats montrent des profils d’évolution distincts sur cellules de mammifères ou de moustiques, illustrant les difficultés liées à l’alternance d’hôte au cours du cycle naturel du CHIKV. La deuxième partie porte sur l’étude chez le CHIKV de la recombinaison génétique, un mécanisme fondamental pour l’évolution des virus à ARN. Les résultats montrent une absence de recombinaison homologue entre virus non défectifs, mais ces expériences ont permis de mettre en évidence la présence de virus délétés qui semblent aider par trans-complémentation la réplication d’un virus atténué. La dernière partie de cette thèse porte sur l’étude de méthodes de génétique inverse qui permettent de générer des virus et d’étudier les mutations associées à l’émergence de certains arbovirus. En utilisant le CHIKV comme modèle, nous avons étudié l’impact qu’ont certaines méthodes sur le génotype et le phénotype du virus in-cellulo et in-vivo chez le moustique. Les résultats montrent une stabilité du phénotype alors que le génotype viral dépend de la méthode utilisée. / Emergence of some pathogenic arboviruses is a major public health concern. The Chikungunya virus (CHIKV) is a typical example of re-emerging pathogen since it recently caused large outbreaks in human population, adapted to a new vector and spread to new areas. This emergence is the consequence of phenomena related to the high genomic plasticity of CHIKV. Understanding the mechanisms of adaptation of arboviruses could help to better control these viral pathogens. The first part of this thesis presents a study of the mutations associated with long-term replication of CHIKV in mammalian and mosquito cells. Our results revealed different evolutionary patterns in mammalian and mosquito cells highlighting the difficulties encountered by arboviruses related to host alternation during their natural cycle. The second part of this thesis deals with the homologous recombination, an important process that play a role in the evolution of RNA viruses. Working with the CHIKV, we did not detect any recombination events between attenuated infectious viruses. However, we detected viruses harboring large genomic deletion that could help an attenuated virus by trans-complementation. The last part of this thesis focused on reverse genetic methods that give the possibility to rescue viruses and can be used to study mutations associated with emergence phenomena. Using the CHIKV as a model, we compared the genotype and the phenotype of viruses generated using different reverse genetic methods in cellulo and in vivo using Aedes mosquitos. Our results showed that the choice of the method influenced the genetic diversity of viral populations but whatever the method used, the phenotype was similar.
5

Fatores associados com o índice de infestação predial do Aedes aegypti em municípios brasileiros no ano de 2012

Frutuoso, Rodrigo Lins January 2013 (has links)
Dissertação (mestrado)—Universidade de Brasília, Faculdade de Ciências da Saúde, Departamento de Saúde Coletiva, 2013. / Submitted by Alaíde Gonçalves dos Santos (alaide@unb.br) on 2013-10-21T12:11:19Z No. of bitstreams: 1 2013_RodrigoLinsFrutuoso.pdf: 1778606 bytes, checksum: 4337d7575c45c940325f61f069e72b58 (MD5) / Approved for entry into archive by Guimaraes Jacqueline(jacqueline.guimaraes@bce.unb.br) on 2013-10-21T12:44:34Z (GMT) No. of bitstreams: 1 2013_RodrigoLinsFrutuoso.pdf: 1778606 bytes, checksum: 4337d7575c45c940325f61f069e72b58 (MD5) / Made available in DSpace on 2013-10-21T12:44:34Z (GMT). No. of bitstreams: 1 2013_RodrigoLinsFrutuoso.pdf: 1778606 bytes, checksum: 4337d7575c45c940325f61f069e72b58 (MD5) / Introdução: A dengue é atualmente a arbovirose de maior magnitude e abrangência geográfica que atinge as populações humanas. No Brasil a epidemia mais recente ocorreu em 2010, com o registro de cerca de 1 milhão de casos. O cenário para o controle dessa doença não é estimulante. A redução da densidade de infestação do Aedes aegypti, ainda permanece como um desafio. Portanto, conhecer os fatores que contribuem para a proliferação do vetor, é de grande utilidade para o planejamento das ações de controle de dengue nos municípios. Objetivo: Verificar a correlação existente entre os fatores ambientais, sociais e de operacionalização dos programas municipais de controle da dengue que influenciaram o Índice de Infestação Predial, no ano de 2012, nos municípios brasileiros contemplados pela portaria n° 2557/2011. Método: O presente trabalho realizou um estudo ecológico, com enfoque na análise bivariada. Inicialmente foram selecionados 1.158 municípios que receberam incentivo financeiro para qualificação das ações de controle da dengue por meio da Portaria 2557/2011. Foram utilizadas variáveis contínuas (IIP, cobertura de imóveis trabalhados pelos agentes de endemias, índice de Desenvolvimento Humano, Densidade Demográfica e Índice de atendimento Urbano de Água) e variável dicotômica (coleta de resíduos sólidos). Os municípios foram agrupados por região geográfica e aqueles que não apresentaram dados referentes às variáveis analisadas, foram automaticamente excluídos do estudo. Para analisar a relação entre as variáveis contínuas, foi utilizado o coeficiente de correlação de Pearson (r), coeficiente de determinação (r2) e gráficos de dispersão. Para a relação entre o IIP e a variável dicotômica, foi utilizada a tabela de contingência. Foi construído um banco de dados em Microsoft Excel 2010, que subsidiou todas as análises do estudo. Resultado: correlação entre cobertura de imóveis trabalhados e IIP: Foi encontrada correlação negativa muito baixa e baixa nas regiões sul e norte, correlação positiva muito baixa nas regiões nordeste e sudeste e na região centro-oeste correlação positiva alta; correlação entre IDH e IIP: Foi encontrada correlação negativa muito baixa e baixa nas regiões nordeste e centro-oeste, correlação positiva baixa nas regiões norte e sudeste e correlação positiva muito baixa na região sul; correlação entre IIP e densidade demográfica: Foi encontrada uma correlação positiva moderada na região norte, correlação inversa baixa nas regiões nordeste e sudeste e correlação inversa muito baixa nas regiões centro-oeste e sul; correlação entre índice de abastecimento urbano de água e IIP: Foi encontrada uma correlação negativa alta na região centro-oeste, uma correlação negativa muito baixa na região sul e correlações positivas muito baixas nas demais regiões; relação entre coleta diária de resíduos sólidos e IIP: Os resultados não permitiram evidenciar a importância deste indicador na manutenção do vetor nos municípios analisados. Conclusão: Com base nos achados a correlação entre o IIP com os indicadores sociais, ambientais e operacionais não apresentaram resultados esperados e concordantes. O presente estudo demonstrou que a política empregada pelo PNCD em relação às ações de controle do vetor deve ser repensada, já que uma alta cobertura de imóveis trabalhados não se traduziu em uma baixa densidade vetorial. _______________________________________________________________________________________ ABSTRACT / Introduction: Nowadays, the dengue is the principal and most widely distributed arbovirose that affect the human population. In Brazil, the most recently outbreak of dengue occurred in 2010 with about 1 million of cases. The scenery to control of this arbovirose is not encouraging. The reduction of the infestation index of the Aedes aegypti remains as a challenge to vector control. Because this, to know the factors that contribute to vector expansion is very important to planning actions in the counties. Goal: This study aimed to verify the association between environmental, social and operational factors of the program vector control that influenced the infestation index, in 2012, in Brazilian municipalities covered for the Portaria n° 2557/2011. Method: An ecologic study focused in bivariate analysis was carried. Firstly, 1.158 municipalities that received financial government support to development of actions of dengue through Portaria 2557/2011 to dengue control were selected. The analyses was realized with the following continuous variables (Household infestation rates (IIP), the number of building visited by Endemic Disease Control Agents, the development human index (IDH), demographic density and index of demand of Urban Water) and dichotomous variable (collection of solid waste). The municipalities were grouped by geographic region. Those who didn’t have data on the variables analyzed were excluded from the study. To analyses the relation between continuous variables were used the Pearson correlation coefficients (r), coefficient of determination (r2) and dispersion graphics. For the analysis of the correlation between IIP and collection of solid waste were used contingencies tables. All analyses were carried using a database constructed in Microsoft Excel 2010 for this study. Result: In the analyses of correlation between building visited and IPII, the results found are: very low and low negative in the South and North regions; very low positive in the Northeast and Southeast and high positive in Midwest. In the analyses between IDH and IPII was found very low and low negative correlation in the Northeast and Midwest regions, low positive correlation in the North and Southeast region; very low positive correlation in the South. In the analyses between IIP e demographic density was found a moderate positive correlation in the North, low inverse correlation in the Northeast and Southeast region and very low inverse correlation in the Midwest and South. In the analyses between index of demand of Urban Water and IIP was found a high negative correlation in the Midwest, a very low correlation in the South and very low positive correlations in the others regions. The results found of the analysis between daily collection of solid waste and IIP didn’t permit to demonstrate that this is an important index to maintain the vectors in these municipalities. Conclusion: The results of the analyses were different of expected data and it presented discrepancies in the correlations between IIP and environmental, social and operational index. This study shows the necessity to review the political of vector control used by PNCD because the high number of visited buildings didn’t interpret in a low vector density.
6

Epidemiological studies on some Sudanese arboviruses

Mohamed, M. E. H. January 1988 (has links)
No description available.
7

Investigation of risk factors for better surveillance and control of arboviruses in Australia /

Kelly-Hope, Louise A. January 2002 (has links) (PDF)
Thesis (Ph. D.)--University of Queensland, 2002. / Includes bibliographical references.
8

Epidemiology of Ross River virus in the south-west of Western Australia and an assessment of genotype involvement in Ross River virus pathogenesis /

Prow, Natalie A. January 2006 (has links)
Thesis (Ph.D.)--University of Western Australia, 2006.
9

Arboviral infection in mosquito vectors : survey and pathogenesis studies /

Neira Oviedo, Marco. January 2005 (has links)
Thesis (Ph.D.)--Ohio University, November, 2005. / Includes bibliographical references (leaves 147-154)
10

Développement du système universel de génétique inverse pour les arboviruses applicable dans les cellules mammifères et moustiques / Development of universal reverse genetics system for arboviruses applicable in mammalian and mosquito cell lines

Atieh, Thérèse 20 December 2017 (has links)
La génétique inverse est la manipulation génétique des virus à ARN pour créer un virus de type sauvage ou modifié. Les techniques de génétique inverse conduit à bien comprendre les fonctions des gènes viraux et leur pathogénicité dans les cellules d’hôte ou de vecteur. Les virus à ARN comme les arbovirus ceux qui ont comme vecteurs les arthropodes représente une vraie menace pour la santé humaine mondiale. Les techniques de génétique inverse sont un moyen adéquat pour protéger l’homme contre les virus par la création des vaccins at par bloquer leur transmission par les vecteurs comme les moustiques. De nos jours, la plupart des systèmes de génétique inverse se concentraient exclusivement sur l’étude d’interaction entre les virus et les cellules de mammifères. Cependant, la transmission de l'arbovirus se situe entre un hôte mammifère et un vecteur d'invertébré.Nous présentons ici ISA (Infectious-Subgenomic-Amplicons) comme une méthode universelle de génétique inverse qui a prouvé son applicabilité sur les cellules de mammifères et de moustiques pour générer des virus infections ARN simple brin de polarité positive.Ainsi, ISA est une méthode adéquate pour étudier le cycle de vie de l'arbovirus chez le moustique vecteur et l'hôte mammifère at ainsi avoir une idée générale de la circulation de l’arbovirus pour créer d’autre outils de blocage. / Reverse genetics, the genetic manipulation of RNA viruses to create a wild-type or modified virus, has led to important advances in our understanding of viral gene function and interaction with host cells. Since arboviruses the most threatening viruses to human and animal are RNA viruses, thus reverse genetics is an extremely powerful technique with important application for the protection from these viruses and to control their spread.Hitherto, most reverse genetics systems focused exclusively on mammalian cells. However, arbovirus transmission is between a mammalian host and invertebrate vector.Herein, we present ISA (Infectious-Subgenomic-Amplicons) as a universal reverse genetic method that proved it applicability to rescue infectious single stranded positive RNA viruses on mammalian and mosquito cells.Thereby, ISA is an adequate method to study the arbovirus life cycle in mosquito vector and mammalian host. Thus, providing information about the global arbovirus circulation to provide further technique that protect mammalian from their infection and inhibit vector to transmit the virus.

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