Thesis (M.Sc.)--York University, 2008. Graduate Programme in Chemistry. / Typescript. Includes bibliographical references (leaves 82-88). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR38748

Dissertation (Ph.D.).--University of Texas Graduate School of Biomedical Sciences at San Antonio, 2007. / Vita. Includes bibliographical references.

Thesis--Leyden. / In Periodical Room. Title on spine: specific binding sites on RNAs and coat protein of AlMV involved in genome activation.

Orientador: Carlos Frederico Wilcken / Resumo:O presente trabalho teve por objetivo caracterizar um novo vírus isométrico, possivelmente do grupo do "CrP-like viruses", isolado de Thyrinteina arnobia (Stoll, 1782) (Lepidoptera: Geometridae), a lagarta parda do eucalipto, e avaliar seu potencial como bioinseticida viral. Os experimentos foram conduzidos nos Laboratórios da FCA/UNESP, Botucatu, SP e ESALQ/USP, Piracicaba, SP. Thyrinteina arnobia Vírus (TaV), proveniente de lagartas doentes coletadas na região de Itatinga em 1996 e Lençóis Paulista SP em 1997, foi multiplicado em lagartas de T. arnobia da criação estoque do laboratório. A mortalidade em lagartas de primeiro ao quarto instar foi de 100%. Fêmeas provenientes de lagartas infectadas no sexto instar originaram adultos com fertilidade bastante reduzida quando comparadas com fêmeas sadias. Através de análises de sobrevivência verificou-se a suscetibilidade em cada instar de lagartas de T. arnobia ao TaV. As lagartas em todos os instares exibiam sintomas característicos de virose. Amostras das suspensões do vírus purificado foram observadas ao microscópio eletrônico de transmissão, sendo visualizada uma grande quantidade de partículas do tipo picornavirus, de aproximadamente 30 nm em diâmetro. Partículas menores de 15 nm, sugerindo vírus satélite, também foram detectadas. As proteínas da capa protéica do TaV foram sorologicamente detectadas usando antissoro produzido em coelho. A capa protéica do vírus é composta de três proteínas de pesos moleculares 47, 60 e 66 kDa. O tamanho do RNA genômico varia entre 4 a 6 kb. Através de secções ultrafinas, verificou-se que a infecção de lagartas de T. arnobia pelo TaV parece limitar-se ao epitélio do tubo digestivo, onde ocorre acúmulo dos vírions. Um efeito citopático característico foi a formação de corpos multivesiculares, aparentemente derivados... (Resumo completo, clicar acesso eletrônico abaixo). / Abstract: The present work aimed to characterize a new virus, possibility belonging to CrPV like viruses group, isolated from Thyrinteina arnobia (Stoll, 1782) (Lepidoptera: Geometridae), the eucalyptus brown looper, and to evaluated its potencial to use as virus bioinsecticide. The experiments were carried out at the laboratory from FCA/UNESP Botucatu - SP and ESALQ/USP Piracicaba- SP. Thyrinteina arnobia virus (TaV) came from sick caterpillars collected in Itatinga, SP in 1996 and in Lençóis Paulista SP in 1997 and colonies were replicated in T. arnobia caterpillars reared in laboratory. The caterpillars mortality from the first to the fourth instar was 100%. Caterpillars infected in the sixth instar and could reach the adult stage showed females with reduced fertility when compared to health ones. Through the survivorship analysis was possible to verify the caterpillars susceptibility to TaV in each T. arnobia instar. All larvae instars exhibited viruses characteristic symptoms. Purified virus suspension samples were observed at the transmission eletronic microscopy and it was visualized a large quantity of picornavirus particles measuring about 30 nm of diameter. Shorter particles with 15 nm were detected, suggesting the existence of satellite virus. The TaV virus cover proteins was serologically detected using antisera produced in rabbit. This cover is composed by three proteins with molecular weight of 47, 60 and 66 kDa. The genomic RNA size varies from 4 to 6 kb. Through ultraslim sections, it was possible to verify that T. arnobia caterpillars infection due to TaV seem to be limited to midgut epithelium, where there has the virions accumulation. The characteristic cytopathic effect was multivesicular bodies formation, apparently due to mitochondrial derivation. Preliminaries assays indicated that TaV did not infect Bombyx mori and Spodoptera... (Complete abstract, click electronic address below). / Doutor

Virus-host interactions determine virus transmissibility and virulence, and underlie coevolution that shapes interesting biological phenomena such as the genetic architecture of host resistance and host range. Characterization of the virus factors that exert selective pressure on the host, and the host genes which underlie resistance and adaptation against viruses will help to define the mechanistic pathways embroiled in host-virus coevolution. In this thesis, I describe the viral causes and host consequences of host-virus coevolution. These include genomic signatures consistent with antagonistic coevolution in antiviral RNA interference pathway genes such as high rates of positive selection and polymorphism, loci that underlie genetic variation in resistance to virus infection, and apparent conflict between NF-κB signalling and DNA virus infection. The RNA interference (RNAi) pathway is the most general innate immune pathway in insects, underlined by the observation that many viruses encode suppressors of RNAi (VSRs). The relationship between RNAi and VSRs has garnered attention as a plausible battleground for host-virus antagonistic coevolution, and genomic patterns in Drosophila support this hypothesis. However, genomic patterns in the N-terminal domain of the key RNAi effector gene, Argonaute-2, have not been described. In Chapter 2, I sequence the Argonaute-2 N-terminal domain using PacBio long-read sequencing technology to describe variation within and across Drosophila species, and test whether this variation is associated with resistance to Drosophila C Virus. The RNAi pathway evolves adaptively in Drosophila, but this has not been formally extended across invertebrate species. In Chapter 3, I quantify rates of adaptive protein evolution and describe evidence for selective sweeps in RNAi pathway genes using population genomic data from 8 insect and nematode species. These analyses indicate that RNAi genes involved in suppression of transposable elements and defence against viruses evolve rapidly across invertebrates, and I identify genes with signatures of elevated adaptation in multiple insect species. Host genes that underlie host-virus interactions have been described in RNA virus infection of Drosophila, however substantially less attention has focussed on the host response to DNA viruses, primarily because no DNA viruses have been isolated from Drosophila. In Chapter 4, I describe the isolation of Kallithea virus, a Drosophila dsDNA nudivirus, and characterise the host response to infection and genetic variation in resistance. I find that Kallithea virus infection causes early male-specific lethality, a cessation of oogenesis, and induction of undescribed virus-responsive genes. Further, I describe genetic variation in resistance and tolerance to Kallithea virus infection, and identify a potential causal variant for virus-induced mortality in Cip4. Insect viruses commonly encode viral suppressors of RNAi, however there are a multitude of antiviral immune mechanisms besides RNAi which may select for viral-encoded inhibitors. In Chapter 5, I describe the requirement for RNAi and NF-κB in immunity against Kallithea virus, and map gp83 as a virus-encoded inhibitor of NF-κB signalling. I find that gp83 inhibits Toll signalling at the level of, or downstream of NF-κB transcription factors, and that this immunosuppressive function is conserved in other nudiviruses.

Thesis (M.Sc.). / Written for the Dept. of Microbiology & Immunology. Title from title page of PDF (viewed 2008/05/14). Includes bibliographical references.

Made available in DSpace on 2014-06-11T19:32:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-08-10Bitstream added on 2014-06-13T19:22:41Z : No. of bitstreams: 1 morais_ats_dr_sjrp.pdf: 1276143 bytes, checksum: 62a89d8b555ac92b5faf4baa19e4db2f (MD5) / O vírus da Febre Amarela (YFV) pertence ao gênero Flavivirus e causa uma importante doença. Nos últimos anos, uma alarmante ressurgência da circulação viral e expansão do vírus em áreas endêmicas têm sido detectadas na África e América do Sul. NS5 é uma proteína viral não estrutural com duas atividades essenciais para a replicação viral, uma de metiltransferase e outra de RNA Polimerase dependente de RNA (RdRp). Para o melhor entendimento dos mecanismos de replicação viral, interações entre NS5 e proteínas celulares têm sido amplamente estudadas. Assim, os objetivos desse estudo foram caracterizar a interação da proteína NS5 e eIF3L, avaliar a função de eIF3L na replicação do vírus da febre amarela, e caracterizar estruturalmente a proteína eIF3L. Métodos. Para identificar a interação de NS5 YFV com eIF3L, foi realizado ensaios em sistema duplo-híbrido usando RdRp NS5 YFV contra eIF3L. Para o mapeamento da interação, foram construídos mutantes deletantes de RNApol e analisados em sistema duplo-híbrido. A região de interação de RNApol foi segmentada em três fragmentos e analisada na presença de eIF3L. Para mapear os resíduos de NS5 críticos para a interação, foi realizada mutagênese sítio-dirigida no segmento 3 de ID. A interação foi analisada em ensaios in vitro e em cultura de células de mamíferos. A significância de eIF3L para a replicação do YFV foi investigada usando superexpressão de eIF3L em células BHK21-RepYF17D LucNeoIres. A proteína eIF3L foi purificada usando uma combinação de cromatografia de afinidade e de exclusão molecular para subsequente caracterização estrutural. Resultados. Nesse estudo, foi caracterizada a interação de NS5 com o fator eucariótico de início de tradução... / Yellow fever virus (YFV) belongs to the Flavivirus genus and causes an important disease. An alarming resurgence of viral circulation and expansion of the YFV endemic zones have been detected in Africa and South America in recent years. NS5 is a viral protein that contains the methyltransferase and RNA-dependent RNA polymerase domains, which are essential during viral replication. Interactions among NS5 and cellular proteins have been studied for the understanding of viral replication. The aim of this study was to characterize the interaction of NS5 protein with EIF3L and evaluate the role of EIF3L in yellow fever replication. Methods. To identify the interaction of YFV NS5 with cellular proteins, we performed a two-hybrid screen using YFV NS5 RdRp domain as bait and a human cDNA library. For mapping the interaction, RNApol deletions mutants were performed and analyses in two-hybrid system. The RNApol region of interaction was segmented in three fragments and analyses into yeast containing eIF3L. To map residues of NS5 that are critical for its interaction, we performed a site-direct mutagenesis in segment 3 of ID. The interaction was confirmed in vitro assays and by in vivo coimmunoprecipitations. The significance of eIF3L for replication of YFV was investigated using overexpression of eIF3L in BHK21-RepYF17D LucNeoIres cells. eIF3L was purified using a combination of affinity and subsequent size exclusion chromatography for subsequent structural characterization. Results. In this work we describe and characterize the interaction of NS5 with the translation factor eIF3L. The interaction between NS5 and eIF3L was confirmed by in vitro binding and in vivo coimmunoprecipitation assays. This interaction occurs in a region (Interaction Domain of RNApol domain) that is conserved in several... (Complete abstract click electronic access below)

Orientador: Maurício Lacerda Nogueira / Banca: Fátima Pereira de Souza / Banca: Cleslei Fernando Zanelli / Banca: Eurico de Arruda Neto / Banca: Luciana Barros de Arruda / Resumo: O vírus da Febre Amarela (YFV) pertence ao gênero Flavivirus e causa uma importante doença. Nos últimos anos, uma alarmante ressurgência da circulação viral e expansão do vírus em áreas endêmicas têm sido detectadas na África e América do Sul. NS5 é uma proteína viral não estrutural com duas atividades essenciais para a replicação viral, uma de metiltransferase e outra de RNA Polimerase dependente de RNA (RdRp). Para o melhor entendimento dos mecanismos de replicação viral, interações entre NS5 e proteínas celulares têm sido amplamente estudadas. Assim, os objetivos desse estudo foram caracterizar a interação da proteína NS5 e eIF3L, avaliar a função de eIF3L na replicação do vírus da febre amarela, e caracterizar estruturalmente a proteína eIF3L. Métodos. Para identificar a interação de NS5 YFV com eIF3L, foi realizado ensaios em sistema duplo-híbrido usando RdRp NS5 YFV contra eIF3L. Para o mapeamento da interação, foram construídos mutantes deletantes de RNApol e analisados em sistema duplo-híbrido. A região de interação de RNApol foi segmentada em três fragmentos e analisada na presença de eIF3L. Para mapear os resíduos de NS5 críticos para a interação, foi realizada mutagênese sítio-dirigida no segmento 3 de ID. A interação foi analisada em ensaios in vitro e em cultura de células de mamíferos. A significância de eIF3L para a replicação do YFV foi investigada usando superexpressão de eIF3L em células BHK21-RepYF17D LucNeoIres. A proteína eIF3L foi purificada usando uma combinação de cromatografia de afinidade e de exclusão molecular para subsequente caracterização estrutural. Resultados. Nesse estudo, foi caracterizada a interação de NS5 com o fator eucariótico de início de tradução... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Yellow fever virus (YFV) belongs to the Flavivirus genus and causes an important disease. An alarming resurgence of viral circulation and expansion of the YFV endemic zones have been detected in Africa and South America in recent years. NS5 is a viral protein that contains the methyltransferase and RNA-dependent RNA polymerase domains, which are essential during viral replication. Interactions among NS5 and cellular proteins have been studied for the understanding of viral replication. The aim of this study was to characterize the interaction of NS5 protein with EIF3L and evaluate the role of EIF3L in yellow fever replication. Methods. To identify the interaction of YFV NS5 with cellular proteins, we performed a two-hybrid screen using YFV NS5 RdRp domain as bait and a human cDNA library. For mapping the interaction, RNApol deletions mutants were performed and analyses in two-hybrid system. The RNApol region of interaction was segmented in three fragments and analyses into yeast containing eIF3L. To map residues of NS5 that are critical for its interaction, we performed a site-direct mutagenesis in segment 3 of ID. The interaction was confirmed in vitro assays and by in vivo coimmunoprecipitations. The significance of eIF3L for replication of YFV was investigated using overexpression of eIF3L in BHK21-RepYF17D LucNeoIres cells. eIF3L was purified using a combination of affinity and subsequent size exclusion chromatography for subsequent structural characterization. Results. In this work we describe and characterize the interaction of NS5 with the translation factor eIF3L. The interaction between NS5 and eIF3L was confirmed by in vitro binding and in vivo coimmunoprecipitation assays. This interaction occurs in a region (Interaction Domain of RNApol domain) that is conserved in several... (Complete abstract click electronic access below) / Doutor

Orientador: Paula Rahal / Banca: Clarice Arns / Banca: João Pessoa Araújo Junior / Banca: Maurício Lacerda Nogueira / Banca: Cristiane Damas Gil / Resumo: A Hepatite C é a inflamação do fígado causada pela infecção pelo vírus da hepatite C (HCV). Essa inflamação ocorre na maioria das pessoas infectadas pelo vírus e, dependendo da intensidade e tempo de duração, pode levar à cirrose e câncer do fígado. No momento não existem vacinas eficazes e o tratamento convencional com peg-IFN e ribavirina tem eficácia bastante limitada e efeitos colaterais graves. Terapias moleculares utilizando a RNAi demonstraram ser eficientes na inibição deste vírus in vitro. O objetivo deste trabalho foi desenvolver diferentes metodologias para inibição da replicação do HCV utilizando-se da técnica de RNAi. Foram desenvolvidas 5 moléculas de dicer substrate siRNA, que em sua maioria foram capazes de reduzir a replicação viral em até 90% em relação ao controle negativo. Ainda, não foi observada a seleção de mutantes resistentes do vírus após o tratamento com os DsiRNAs por 21 dias. Também foram desenvolvidos 3 vetores lentivirais contendo sequencias codificantes de shRNA contra o HCV. Com a utilização destas partículas lentivirais foi possível reduzir a replicação do HCV em aproximadamente 99% em relação ao controle negativo. Neste estudo foi demonstrado que o HCV pode ser inibido eficientemente utilizando tecnologias distintas de RNAi. Os DsiRNAs são mais potentes que os tradicionais siRNAs e com menor probabilidade de selecionar mutantes resistentes. Os vetores lentivirais são eficientes na entrega dos genes contendo os shRNAs e potentes na inibição do HCV. Ambas as tecnologias no futuro poderão ser utilizadas na terapia alternativa de pacientes crônicos ou no caso dos DsiRNAs de forma preventiva à infecção / Abstract: Hepatitis C virus (HCV) frequently establishes persistent infections in the liver, leading to the development of chronic hepatitis, and, potentially, to liver cirrhosis and hepatocellular carcinoma at later stages. No vaccine is available for HCV and the current standard of care, which consists of pegylated interferon-α and ribavirin, has limited efficacy against certain HCV genotypes, and also produces significant adverse effects. Molecular therapies have proven to be effective in the inhibition of the virus in vitro. Molecular therapies based on RNAi has shown good efficiency on knockdown of HCV in vitro.The aim of this study was to develop different methodologies for inhibiting HCV replication using the RNAi technique. We developed five dicer substrate siRNA molecules, which mostly were able to reduce viral replication by 90% compared to the negative control. Still, there was no selection of resistant mutants of the virus after treatment with DsiRNAs for 21 days. In addition, we developed lentiviral vectors containing sequences encoding shRNA against HCV. With the use of these lentiviral particles, it was possible to reduce HCV replication by approximately 99% compared to negative control. In this study, it was demonstrated that HCV could be effectively inhibited using different RNAi technologies. The DsiRNAs are more powerful than traditional siRNAs and less likely to select resistant mutants. The lentiviral vectors are efficient in delivery of genes containing shRNAs and potent in the inhibition of HCV. Both technologies in the future may be used in alternative therapy for chronic patients or in case of DsiRNAs preventively to infection / Doutor

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.