No description available.

Polyomaviruses are small, DNA tumor viruses that establish persistent infections in their natural hosts. Several members of the virus family are associated with human pathologies such as Progressive Multifocal Leukoencephalopathy (PML), trichodysplasia spinulosa and Merkel cell carcinoma. Polyomaviruses are one of the first virus family known to encode miRNAs. These polyomaviral miRNAs are located antisense to the early transcripts and hence, mediate the autoregulation of the viral early proteins, the T antigens. There are two major questions in the field of polyomaviral miRNAs – What is the biological significance of this miRNA-mediated autoregulation of the early transcripts? Are there other biological significant targets for these polyomaviral miRNAs? This work addressed these two questions through an evolutionary approach. First, examination of SV40 and JCV variants indicated the high conservation of the miRNAs and their autoregulatory functions. Second, miRNA-mediated autoregulation of the early transcripts is conserved in a newly discovered, evolutionarily divergent viruses, the Bandicoot papillomatosis and Carcinomatosis viruses (BPCVs). Third, by inspecting divergent members of the polyomavirus family, we have shown that some non-human polyomaviruses encode miRNAs, with the function to autoregulate the early transcripts conserved. The conservation of miRNAs both among variants of individual member and across divergent members of the polyomavirus family implies importance. More importantly, a conserved function of autoregulating the early transcript further emphasized the biological relevance of the miRNAs in polyomavirus biology. Yet, the lack of replicative differences between miRNA-expressing and miRNA-null SV40 strains during lytic infections suggests a role for the polyomaviral miRNAs under a different setting, perhaps in the establishment of persistent infection of their natural hosts. This work represents an evolutionary study of polyomaviral miRNAs that has demonstrated the conserved nature of miRNA-mediated autoregulation of the early transcripts among various members of the polyomavirus and polyoma-like virus families. These results have implicated a potential role for the polyomaviral miRNAs in the establishment of persistent infection and raised the possibility of using the JCV miRNAs as potential biomarkers as a non-invasive form of diagnostic for PML. / text

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas, Programa de Pós-Graduação em Biotecnologia e Biociências, Florianópolis, 2014. / Made available in DSpace on 2015-04-29T21:01:48Z (GMT). No. of bitstreams: 1 328079.pdf: 2882148 bytes, checksum: 0d8f6b84f74603e020abbf3892564514 (MD5) Previous issue date: 2014 / Pacientes imunodeprimidos podem apresentar infecções virais com evolução rápida, sintomatologias atípicas graves e muitas vezes fatais, sendo fundamental um diagnóstico precoce para estabelecimento do tratamento efetivo, redução da toxicidade e da resistência aos antivirais. HSV-1, HSV-2 e poliomavírus BK são vírus de importância clínica para imunodeprimidos e podem levar a rejeição de órgãos em transplantados. Assim, o objetivo deste trabalho foi desenvolver um sistema celular repórter, utilizando a proteína fluorescente GFP, para HSV-1 e 2 e implantar uma qPCR utilizando amostras clínicas de pacientes transplantados renais para detecção de poliomavírus BK. O sistema celular repórter foi construído através da transfecção de células Vero com o vetor pZsGreen1-1 ligado ao promotor ICP10 (F3R3 e F4R3) da RR1 do HSV-2. A regulação da expressão da GFP via ICP10 é dependente da infecção viral e acontece por meio da proteína viral transativadora VP16 e de fatores celulares Oct-1 e HCF-1. A efetividade do sistema foi avaliada por infecção viral e pela aplicação de antivirais (Aciclovir, ácido gálico, convalotoxina e extrato de Uncaria sp.) e candidatos antivirais inativos (Extrato de Passiflora edulis e derivados de cardenolídeos). O sistema repórter F4R3 ZsGreen1-1 expressou GFP em função da infecção por HSV-1 e 2, a qual foi detectada por microscopia de fluorescência e/ou citometria de fluxo. Em análise por citometria de fluxo, a fluorescência do sistema repórter correlacionou-se diretamente com os títulos virais (MOI de 4,0 x10-3 a 3,3 x10-4, ou seja, 1 partícula viral a cada 250 a 3000 células), o sistema manteve a capacidade de expressão da GFP na presença de agentes sem propriedade antiviral e não expressou fluorescência quando tratado com antivirais. O sistema F4R3 ZsGreen1-1 mostrou-se um sistema funcional com possíveis aplicações para diagnóstico clínico, para elaboração de testes de resistência aos antivirais e para a pesquisa de novos medicamentos. A qPCR para poliomavírus BK foi implantada utilizando amostras de DNA cedidas pelo HEMOSC com iniciadores dirigidos para o antígeno T viral. O limite de detecção foi de 18 cópias genômicas/ reação com quantificações variando entre 9,8 x 105 a 6,7 x 107 cópias genômicas/ mL. A qPCR foi efetiva para análises de amostras clínicas e apresentou limite de detecção suficiente para avaliação de risco de nefropatia em transplantados renais.<br> / Abstract : Immunosuppressed patients can present viral infections with fast evolution, severe atypical symptomatologies and often fatal, being essential the early diagnosis for the establishment of effective treatments, reduction of toxicity and development of resistance to antiviral. HSV-1, HSV-2 and polyomavirus BK are virus of clinical importance for immunosuppresed and can lead to the rejection of transplanted organs. Therefore, the aim of this work was to develop a reporter cellular system, using the fluorescent protein GFP, for HSV-1 and 2, and deploy a qPCR using clinical samples from patients submitted to renal transplant, for the detection of polyomavirus BK. The reporter cellular system was constructed through the transfection of Vero cells with the vector pZsGreen1-1 connected to the promoter ICP10 (F3R3 and F4R3) of the RR1 of the HSV-2. The regulation of the expression of GFP via ICP10 is dependent of the viral infection and happens through the viral transactivating protein VP16, and the cellular factors Oct-1 and HCF-1. The effectivity of the system was evaluated by viral infection and through the application of antiviral (Acyclovir, gallic acid, convalotoxina and extract of Uncaria sp.) and inactive antiviral candidate (Extract of Passiflora edulis and derivatives cardenolide). The reporter system F4R3 ZsGreen1-1 expressed GFP as a function of the infection for HSV-1 and 2, which was detected by fluorescence microscopy and/or flow cytometry. In flow cytometry, the fluorescence of the reporter system was directly correlated with virus titers (MOI 4,0 x10-3 to 3,3 x10-4, that is, 1 viral particle to each 250 to 3000 cells), the system maintained the ability to GFP expression in the presence of agents without antiviral property and no expressed fluorescence when treated with antivirals. The system F4R3 ZsGreen1-1 revealed a functional system with possible applications for clinical diagnosis, elaboration of tests of resistance to the antiviral and for new drugs research. The qPCR to polyomavirus BK was deployed using DNA samples provided by HEMOSC with primers directed to the viral antigen T. The limit of detection was 18 genome copies /reaction with quantification ranging between 9.8 x 105 to 6.7 x 107 genome copies /mL. The qPCR was effective for the analyses of clinical samples and presented enough sensitivity for risk evaluation of nephropathy in renal transplant.

Polyomaviruses are small non-enveloped DNA viruses infecting birds and mammals, including human. Their capsid consists of the major capsid protein, VP1, and two minor capsid proteins, VP2 and VP3. The VP2 and VP3 proteins are supposed to have an important function in the transport of viral genome into the cell nucleus, which is a key step to facilitate viral replication. VP2 and VP3 proteins of mouse polyomavirus and SV40 have an ability to bind and disrupt cellular membranes. This feature is believed to be involved in the transport of viral genome into the nucleus. Plasmids carrying genes of the minor capsid proteins of Merkel cell polyomavirus were prepared in order to produce and visualize these proteins in mammalian cells. These proteins are known to have very unusual sequences compared to other human polyomaviruses or related mouse polyomavirus. When produced alone, the minor capsid proteins of Merkel cell polyomavirus did not significantly interact with cellular membranes, unlike the minor proteins of the mouse polyomavirus. The second goal of this work was to prepare mouse polyomavirus mutants with deletion in hydrophobic domains of VP2 and VP3 proteins. These domains are likely responsible for the mentioned membrane interactions. Prepared mutants were non-infectious. The loss of infectivity was not...

Mouse polyomavirus (MPyV) is a small non-enveloped virus. Its capsid consists of 72 pentamers of the major capsid protein VP1. The central cavity of each VP1 pentamer contains one minor capsid protein, either VP2, or VP3. The minor capsid proteins are dispensable for capsid formation, but their presence is required for infection of the host cell, presumably because of their anticipated functions during virus entry. After internalization, MPyV virions traffic to endoplasmic reticulum (ER). VP2 and VP3 have been proposed to function as factors responsible for penetration of ER membranes, which is required for subsequent delivery of the viral DNA into the nucleus, a key step of the early phase of MPyV infection. Three hydrophobic domains were predicted in the sequence of VP2 and VP3. First in the unique Nterminal part of VP2, second and third in the common part of VP2 and VP3. The third domain corresponds to C-terminal VP1binding alpha-helix. It has been previously found in our laboratory, that VP2 and VP3 fused to N-terminus of EGFP, when expressed in mammalian cells, display properties similiar to the wild-type VP2 and VP3, namely affinity to intracellular membranes and high cytotoxicity. Expression plasmids carrying mutated VP2 and VP3 fused to Nterminus of EGFP were prepared to determine the hydrophobic...

Le polyomavirus BK (ou BKPyV) est un virus ubiquitaire qui infecte plus de 80% de la population adulte. Asymptomatique chez le sujet immunocompétent, il peut être la cause de cystites hémorragiques chez les greffés de cellules souches hématopoïétiques ou de néphropathies interstitielles après transplantation rénale. Parmi les facteurs de risques impliqués dans le développement des néphropathies à BKPyV, nous nous sommes intéressés à l’étude de la variabilité de la région régulatrice non codante (NCCR) du génome viral et à la réponse immunitaire cellulaire spécifique anti- BKPyV en post-greffe. La région NCCR du BKPyV est caractérisée par l’apparition de réarrangements (rrNCCR) chez certains patients présentant une virémie intense et prolongée. Ces réarrangements sont également observés in vitro au cours de la multiplication virale sur cellules permissives. Dans le but de caractériser les rrNCCR et d’étudier leur impact sur la réplication virale, nous avons étudié l’émergence de ces réarrangements in vitro et in vivo sur des échantillons cliniques d’une cohorte de transplantés du rein du CHU de Nantes. Par ailleurs, nous avons étudié la réponse spécifique anti-BKPyV dans les premiers mois postgreffe dans une cohorte prospective de patients adultes transplantés de rein. Nos résultats montrent une augmentation du taux des anticorps au cours de l’infection, et l’absence de valeur prédictive de la réponse médiée par les lymphocytes T sur la survenue d’une infection active à BKPyV. L’ensemble de ces résultats contribue à une meilleure compréhension des mécanismes en jeu au cours des infections à BKPyV en transplantation rénale. / The BK polyomavirus is ubiquitous and infects the majority of the adult population. It is not associated with any specific disease in immunocompetent individuals, but can be responsible for hemorrhagic cystitis after stem cell transplantation or interstitial nephropathy after kidney transplantation. Among the different risk factors involved in the development of such opportunistic diseases, we focused on the genetic polymorphism of the non coding control region of the viral genome (NCCR) and on the specific immune responses directed against BKPyV after kidney transplantation. The NCCR region is characterized by the emergence of rearrangements in vitro on permissive cells, and in vivo in case of prolonged infection and high viral loads. We described the emergence of such rearranged strains in vitro, correlated them with increased viral replication and transcription, and compared these sequences with clinical strains obtained from kidney transplanted patients. Our second objective was to study the specific immune responses in the first months following kidney transplantation. We showed that the active infection was associated with an increase in the anti-BKPyV IgG levels, and that the detection of a CD4+ or CD8+ mediated response was not predictive of a protection toward viral reactivation. Our results contribute to a better understanding of the different factors involved in the pathogenesis of BKPyV infections.

Trichodysplasia spinulosa (TS) é uma doença proliferativa de pele observada em pacientes imunocomprometidos. Caracteriza-se pela formação de espinhas de queratina conhecidos como espículas, acantose epidérmica, dilatação do folículo piloso, queratose actínica, queda dos pelos, pápulas foliculares e, que normalmente, se manifestam na região facial do paciente e extremidades do corpo (constantemente confundida com danos por exposição prolongada ao sol). A TS resulta da infecção ativa com o poliomavírus TSassociado (TSPyV), onde observa-se alta carga viral, expressão de proteína do vírus e formação de partículas. Este estudo desenvolveu métodos moleculares de detecção e sequenciamento do genoma total e parcial de TSPyV e utilizou-se destes métodos para determinar padrões de excreção e viremia em indivíduos imunocompromentidos e imunocompetentes, bem como explorar possíveis vias de transmissão. Ainda, características genéticas e filogenéticas do TSPyV também foram determinadas. Apesar de observamos alta taxa de excreção urinaria em indivíduos imunocomprometidos (57,7%), o vírus não foi encontrado em amostras de água do meio ambiente. Ainda em termos de excreção urinária do TSPyV, apenas 1,4% dos indivíduos imunocompetentes apresentaram virúria (diferente do que se observa para os poliomavirus JCPyV e BKPyV), mas o vírus foi encontrado em leite materno, sugerindo assim a possibilidade de haver transmissão vertical do TSPyV. As análises filogenéticas revelaram a existência de 2 linhagens de vírus circulantes em nosso meio, com características distintas dos já descritos na literatura. As diferenças observadas foram suficientes para que os vírus sejam caracterizados como novos genótipos circulantes de TSPyV. / Trichodysplasia spinulosa (TS) is a proliferative skin disease seen in immunocompromised patients. It is characterized by the formation of keratin spines known as spicules, epidermal acanthosis, hair follicle dilatation, actinic keratosis, hair loss, follicular papules and, which usually manifest in the facial region and extremities of the body (constantly confounded with damage from prolonged exposure to the sun). TS results from active infection with TS-associated polyomavirus (TSPyV), where high viral load, virus protein expression and particle formation are observed. This study developed molecular methods for detection and sequencing the total and partial genome of TSPyV and, employing these methods, determined patterns of excretion and viremia in immunocompromised and immunocompetent individuals, as well as explored possible transmission pathways. Genetic and phylogenetic characteristics were also determined. Although we observed high rate of urinary shedding in immunocompromised individuals (57.7%), the virus was not found in environmental water samples. Also in terms of urinary excretion of TSPyV, only 1.4% of immunocompetent individuals presented viruria (different from what is observed for polyomaviruses JCPyV and BKPyV), but the virus was found in breast milk, thus suggesting the possibility of vertical transmission. Phylogenetic analyzes revealed the existence of 2 circulating virus strains in our country, with different characteristics from those already described in the literature. The differences seem to be sufficient to characterize the viruses as new genotypes of TSPyV.

Trichodysplasia spinulosa (TS) é uma doença proliferativa de pele observada em pacientes imunocomprometidos. Caracteriza-se pela formação de espinhas de queratina conhecidos como espículas, acantose epidérmica, dilatação do folículo piloso, queratose actínica, queda dos pelos, pápulas foliculares e, que normalmente, se manifestam na região facial do paciente e extremidades do corpo (constantemente confundida com danos por exposição prolongada ao sol). A TS resulta da infecção ativa com o poliomavírus TSassociado (TSPyV), onde observa-se alta carga viral, expressão de proteína do vírus e formação de partículas. Este estudo desenvolveu métodos moleculares de detecção e sequenciamento do genoma total e parcial de TSPyV e utilizou-se destes métodos para determinar padrões de excreção e viremia em indivíduos imunocompromentidos e imunocompetentes, bem como explorar possíveis vias de transmissão. Ainda, características genéticas e filogenéticas do TSPyV também foram determinadas. Apesar de observamos alta taxa de excreção urinaria em indivíduos imunocomprometidos (57,7%), o vírus não foi encontrado em amostras de água do meio ambiente. Ainda em termos de excreção urinária do TSPyV, apenas 1,4% dos indivíduos imunocompetentes apresentaram virúria (diferente do que se observa para os poliomavirus JCPyV e BKPyV), mas o vírus foi encontrado em leite materno, sugerindo assim a possibilidade de haver transmissão vertical do TSPyV. As análises filogenéticas revelaram a existência de 2 linhagens de vírus circulantes em nosso meio, com características distintas dos já descritos na literatura. As diferenças observadas foram suficientes para que os vírus sejam caracterizados como novos genótipos circulantes de TSPyV. / Trichodysplasia spinulosa (TS) is a proliferative skin disease seen in immunocompromised patients. It is characterized by the formation of keratin spines known as spicules, epidermal acanthosis, hair follicle dilatation, actinic keratosis, hair loss, follicular papules and, which usually manifest in the facial region and extremities of the body (constantly confounded with damage from prolonged exposure to the sun). TS results from active infection with TS-associated polyomavirus (TSPyV), where high viral load, virus protein expression and particle formation are observed. This study developed molecular methods for detection and sequencing the total and partial genome of TSPyV and, employing these methods, determined patterns of excretion and viremia in immunocompromised and immunocompetent individuals, as well as explored possible transmission pathways. Genetic and phylogenetic characteristics were also determined. Although we observed high rate of urinary shedding in immunocompromised individuals (57.7%), the virus was not found in environmental water samples. Also in terms of urinary excretion of TSPyV, only 1.4% of immunocompetent individuals presented viruria (different from what is observed for polyomaviruses JCPyV and BKPyV), but the virus was found in breast milk, thus suggesting the possibility of vertical transmission. Phylogenetic analyzes revealed the existence of 2 circulating virus strains in our country, with different characteristics from those already described in the literature. The differences seem to be sufficient to characterize the viruses as new genotypes of TSPyV.

This thesis is missing page 157, the other copies of the thesis did not have the page either. -Digitization Centr / The polyomavirus enhancer is organized into three elements. One of these elements, Element 2, is particularly interesting because the activities of the factors which interact with it are highly regulated. There are at least three cellular proteins, PEA1, PEA2, and PEA3, which bind to adjacent sites in Element 2. These proteins are differentially active in mouse cells at different developmental stages and their activity is modulated by serum, tumor promoting agents and the products of several oncogenes. It is likely, therefore, that these cellular proteins play an important role in interpreting growth stimuli and other physiological cues in the mouse. A plasmid was contructed which can be used to test enhancer elements for their ability to activate both transcription and DNA replication. This plasmid includes the Py origin of replication and a minimal promoter, consisting of a TATA box only, controlling expression of a reporter gene. The activity of the PEA factors was studied by cloning the binding sites for these factors into this reporter plasmid as monomers, multiple tandem copies, and in paired combinations, and testing their ability to activate transcription and DNA replication in vivo. The results of these studies show that PEA1 and PEA3 can function independently and cooperatively to activate both replication and transcription. By contrast, PEA2 is unable to independently activate transcription and represses PEA1-activated transcription when the binding sites for these factors are located adjacent to one another. However, PEA2 functions cooperatively with PEA1 to activate DNA replication, and can weakly activate replication on its own. / Thesis / Master of Science (MS)

The main structural protein VP1 is the product of late polyomaviral genes and it is the largest and the most abundant protein of the whole polyomaviral capsid. Because of the low coding capacity of the polyomaviral genomes, it is considered that in addition to its structural role the VP1 protein might have some additional functions in the late phase of the infectious cycle. This diploma thesis is exactly on these additional functions. In the case of the VP1 protein of mouse polyomavirus, it was observed that the protein is capable of binding to the structure of cellular microtubules. The first objective of this work was to test whether pentamers of the VP1 protein are able of this binding without the participation of other cellular (or viral) proteins. Based on an in vitro experiment, we showed that protein VP1 binds to the structure of microtubules very inefficiently. The second objective of this work was to prepare a detection system that would allow an identification of potential interaction partners of BK polyomavirus VP1 protein. Therefore, expression plasmids producing the N and C-terminally tagged VP1 protein were prepared. These tagged proteins had the property of being biotinylated whilst being produced in the transfected cells. By using affinity chromatography, the entire protein complexes...