Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2006. / Härtill 4 uppsatser.

En 2008, le génome d’un nouveau virus a été caractérisé au sein d’un cancer cutané rare survenant préférentiellement chez l’immunodéprimé, le carcinome de Merkel. Ce nouveau virus appartenait à la famille des Polyomaviridae qui comprend des virus dont le caractère cancérigène chez l’animal est avéré depuis plus de 50 ans. Dénommé Polyomavirus de Merkel puisqu’il semblait lié à la survenue du cancer du même nom, il constituait le premier Polyomavirus impliqué de manière consistante dans un cancer humain. Cette implication reposant sur une étude unique limitée à 10 cas, l’objectif de notre travail de thèse était de confirmer le rôle étiologique du Polyomavirus de Merkel dans le carcinome de Merkel.Nous avons montré que le génome du Polyomavirus de Merkel était présent dans les trois quarts des cas de carcinome de Merkel, mais également que le virus infecte la population générale de manière quasi-ubiquitaire et de nombreux tissus en dehors de la peau. Les faits que chez les sujets atteints de carcinome de Merkel, l’ADN viral soit présent à des taux décelables de manière chronique dans différents tissus et que les titres d’anticorps sériques spécifiques du virus soient élevés suggèrent que ces sujets développent une infection chronique active. Celle-ci pourrait faciliter la survenue de mutations et d’intégrations de l’ADN viral qui sont spécifiquement associées aux carcinomes de Merkel. Ces modifications secondaires du génome viral aboutissent à la production d’oncoprotéines virales par les cellules tumorales, mais à l’abolition des capacités réplicatives donc lytiques du virus et constitueraient ainsi le support de la transformation tumorale. / Nucleotidic sequences defining the genome of a new virus, the Merkel Cell Polyomavirus, has been discovered in 2008 in Merkel cell carcinoma, a rare form of cutaneous cancer developing mostly in immunosupressed individuals. Whereas this new virus belongs to the Polyomaviridae family, which includes known oncogenic viruses in animals, it was the first study consistently implicating a Polyomavirus in human cancer. Because scientific arguments were only based on a ten-case-single report, the primary goal of our work was to confirm the role of the Merkel Cell Polyomavirus in Merkel Cell Carcinoma.Our work demonstrated that Merkel Cell Polyomavirus DNA was indeed present in three quarters of Merkel Cell Carcinoma cases, but also that Merkel Cell Polyomavirus was a near ubiquitous virus infecting various tissues among healthy individuals. Nonetheless, viral DNA is chronically detected in various tissues from Merkel Cell Carcinoma cases, which harbour elevated seric titters of specific antibodies. Those facts suggest that Merkel Cell Polyomavirus develop an active and chronic infection that could favour genomic mutation and integration events specifically associated to Merkel Cell Carcinoma. Those modifications, inducing both expression of truncated viral oncoproteins and abolishment of cell lysis mediated by viral replication, may support cell transformation.

Les réactivations à Polyomavirus, BK-virus (BKv) et JC-virus (JCv), sont des complications majeures en transplantation rénale, responsables de néphropathie à BKv (Nx BKv) et de leuco-encéphalopathie multifocale progressive (LEMP). Sans thérapeutique antivirale spécifique, ces infections virales menent à la perte du rein transplanté ou au décès du patient. Notre groupe a conduit une étude observationnelle incluant 100 patients transplantés rénaux avec différents niveaux de réactivation BKv (Etude MelTyK). Nous avons mis en évidence une altération progressive de la fonctionnalité des lymphocytes T spécifiques du BKv, associée à une corrélation inverse entre la polyfonctionnalité lymphocytaire ou le nombre d’incompatibilités HLA et la charge virale BKv plasmatique. Cette altération de la fonctionnalité suggérait un état d’épuisement des lymphocytes T spécifiques du BKv en fonction du niveau de réactivation BKv. Ces données nous ont conduit à élaborer une méthode biologique non-invasive d’évaluation du risque individuel de Nx BKv (brevet FR1855342). Cette méthode a pour objectif d’aider au diagnostic de Nx BKv sans avoir recours à la biopsie du greffon rénal et de stratifier le risque de développer cette complication. Par ailleurs, nous avons décrit un cas fatal de LEMP associé à un état d’anergie des lymphocytes T spécifiques du JCv. L’étude de la fonctionnalité des lymphocytes T spécifiques des Polyomavirus pourrait ouvrir de futures pistes diagnostiques et/ou thérapeutiques. Elle pourrait permettre de dépister les patients à risques de Nx BKv et pourrait contribuer au développement d’immunothérapies innovantes. La restauration de la fonctionalité des lymphocytes T spécifiques des Polyomavirus pourrait ainsi fournir une piste thérapeutique prometteuse afin de contrôler ces réactivations virales sans majorer le risque de rejet allogénique. / Polyomavirus reactivations, BK-virus (BKv) and JC-virus (JCv), are major complications in kidney transplantation, responsable of BKv associated nephropathy (BKvAN) and progressive multifocal leukoencephalopathy (PML). Without antiviral treatment, these viral reactivations lead to kidney transplant loss or patient death. Our group has headed an observational study including 100 kidney transplant recipients with different BKv reactivation levels (the MelTyK study). We were able to highlight a gradual loss of functional BKv-specific T cells, associated with an inverse correlation between lymphocyte functionality or HLA mismatches and plasmatic BKv viral load. This functional impairment suggested an exhaustion of BKv-specific T cells according to BKv reactivation levels. These data have led us to develop a non-invasive biological method to assess the individual BKvAN risk (patent FR1855342). This method is intended to help the BKvAN diagnosis, without renal graft biopsy and to stratify the risk to develop this complication. Moreover, we have described a fatal case of PML associated with a anergy state of the JCv-specific T cells. Functional assessment of Polyomavirus-specific T cells could help to propose new diagnostic assays and immunotherapy approaches. Functional restauration of Polyomavirus-specific T cells could provide a promising therapeutic approache to control viral reactivations without increase of allogenic rejection risk.

Major capside protein of Polyomaviridae family viruses is able to selfassemble into virus-like particle (VLP) even without the presence of minor proteins, bind exogenous DNA non-specifically and recognise the receptor on the cellular surface. These characteristics determine its use as vector in gene therapy or immunotherapy. It was discovered before that MPyV VLPs significantly stimulate immune system and have strong adjuvant effect. Chimeric VLP derived from mouse polyomavirus carrying exogenous antigene or epitop is supposed to elicit specifically targeted immune response after immunisation. The main obstacle is choice of immunogene that is strong enough to cause adequate immune response. The goal of this thesis was to construct chimeric particles carrying epitop of malignant melanoma, one of the most immunogenic tumours, on their surface, using methods of genetic engineering. For future research of particle's immunogenic properties three types of particles were developed - particles with human and mouse melanoma epitopes, respectively and control particles with ovalbumine epitop. For the purpose of production of chimeric protein was used baculovirus expression system. It was verified then, with the use of electron microscopy, that introduction of tumour antigen into one of surface loops of VP1...

Le polyomavirus BK est un virus très prévalent qui demeure normalement en phase de latence dans l’uroépithélium sans entrainer de complications. Chez les greffés rénaux, il peut cependant se réactiver et mener à une néphropathie pouvant nuire à la survie du greffon. L’immunité du receveur est la pierre angulaire de la prévention et du traitement de cette néphropathie, puisque le seul traitement démontré efficace est une diminution de l’immunosuppression. Cependant, une augmentation non spécifique de l’immunité augmente également le risque de rejet. Notre objectif était donc d’adapter et de valider un protocole transférable en clinique d’immunothérapie adoptive antivirale nous permettant de produire des lignées de lymphocytes T BKvirus spécifiques à partir du sang de patients greffés virémiques, afin de prévenir et traiter ces néphropathies. Nous avons tout d’abord comparé les lignées cellulaires produites à partir de donneurs sains à celles de patients immunosupprimés soumis à une immunosuppression chronique. Par la suite, nous avons adapté le protocole en ajoutant une stimulation à l’aide de cellules dendritiques afin de maximiser l’expansion cellulaire, le statut de différentiation et la spécificité. Bien que les lignées étaient polyclonales, elles n’ont pas démontré de potentiel alloréactif in vivo et in vitro, et ce, malgré une persistance et une prolifération in vivo. Nous avons donc élaboré un protocole qui est prêt à être transféré en étude clinique de phase I/II et qui pourrait nous permettre de prévenir et traiter la néphropathie associée au polyomavirus BK, sans augmenter le risque de rejet. / More than 75% of the population has been exposed to BK polyomavirus and carries latent virus in the uroepithelium without any complications. However, it can reactivates in kidney transplant recipients (KTR) and lead to a nephropathy affecting graft survival. Recipient anti-viral immunity is the cornerstone of BK-virus associated nephropathy prevention and treatment and thus, reduction of immunosuppression is the only well-accepted treatment. Adoptive immunotherapy is a promising solution to this problem, allowing a specific T cell mediated response against this virus without the alloreactive risk. It was demonstrated efficacious for other viral infections in immunocompromised hosts but it has not been used in this specific context. Our objective was to adapt and validate a clinical-compliant protocol to obtain BK-specific T cell lines from viremic KTR and to compare their expansion, differentiation and specificity to ones obtained from healthy donors. Although comparable specificity and differentiation status, cell expansions form KTR were not systematically sufficient for a therapeutic dose. The addition of a stimulation with dendritic cells improved cell expansion in addition to favors a central memory phenotype and refined BKspecificity. Despite polyclonality, T cell lines didn’t demonstrated alloreactivity in a chromium release assay and in vivo. Furthermore, T cell lines could persist and proliferates in vivo. This protocol is ready for a phase I/II clinical trial. This opens the possibility to solve the current conundrum and treat PVAN without increasing rejection risk.

Viral particles derived from mouse polyomavirus can be potentially used as a delivery system for therapeutic genes and drugs into target cells. This thesis focuses on preparation and characterization of polyomaviral particles that are modified with cell-penetrating peptides in order to increase efficiency of transduction of reporter genes into human cells. Viral particles that are composed of major capsid protein VP1 in combination with minor capsid protein VP2 and minor capsid protein VP3 that is modified with octaarginine, LAH4 peptide or with transduction domain of adenoviral protein VI are analysed in transduction assays. The thesis also provides information about the effect of the modification on encapsidation of heterologous DNA. The results of transduction assays performed with modified particles containing encapsidated luciferase gene revealed that efficiency of transduction did not increase but decreased in comparison with unmodified particles. These findings help to elucidate the role of polyomaviral minor capsid proteins in gene transfer mediated by viral particles and contribute to the design of new strategies for modifications of viral particles derived from mouse polyomavirus for their successful application in nanomedicine. Key words: mouse polyomavirus, pseudovirions, virus-like...

Os poliomavírus compõem uma grande família de vírus que causam infecções primárias geralmente na infância, e se mantem em condições subclínicas. Em situações de imunossupressão podem causar algumas doenças. Os indivíduos com HIV/AIDS frequentemente apresentam deficiência imunológica e por isso podem exibir maior risco de doenças causadas pelos poliomavírus. A utilização da saliva no diagnóstico e acompanhamento de doenças infecciosas tem sido explorado na literatura. As vantagens de usar a saliva para rastreio se pautam especialmente na coleta não invasiva e segurança no manuseio. O presente estudo teve como objetivo, detectar e quantificar o DNA dos poliomavírus BKV, JCV, de células Merkel e TSV, em fluídos orais (saliva, lavado bucal e fluído gengival crevicular) e comparar com a detecção em soro e urina, meios usualmente utilizados para detecção. Foram coletadas 299 amostras de 42 indivíduos, sendo 22 HIV positivos (GE) e 20 pacientes controle (GC). No GE, 63,6% dos pacientes apresentaram positividade para JCV em pelo menos uma amostra analisada, 54,5% foram positivos para BKV, 18,2% para células Merkel e não houve amostra positiva para TSV. No GC, 45% exibiu positividade para o JCV em pelo menos uma amostra analisada, 80% para BKV e nenhuma participante controle exibiu positividade para células Merkel e TSV. Não houve diferença de frequência de detecção viral entre os grupos estudados em relação às amostras coletadas, ou ainda em relação à idade ou sexo. Entretanto, nas amostras de fluídos orais houve maior prevalência de detecção para o BKV e para células Merkel. Concluímos que fluídos orais, especialmente saliva e lavado bucal, podem ser usados para o rastreamento do BK e JC; e que os indivíduos HIV positivos, sob tratamento antirretroviral não exibem frequências maior de poliomavírus, comparativamente a indivíduos controle. / Polyomavirus is one of the large family of viruses that cause primary infections usually in childhood, and can remain subclinical. In immunosuppression may cause some diseases. Individuals with HIV/AIDS often have immune deficiencies and may be at increased risk for diseases caused by polyomaviruses. The use of saliva in the diagnosis and follow-up of infectious diseases has been explored in the literature. The advantages of using saliva for screening are based on non-invasive collection and handling safety. The aim of present study was to detect and quantify the DNA from BKV, JCV, Merkel cell and TSV polyomaviruses in oral fluids (saliva, mouthwash and gingival crevicular fluid) and to compare it with serum and urine detection, the means usually used for detection. A total of 299 samples were collected from 42 individuals, 22 HIV positive (GE) and 20 control patients (GC). In GE, 63,6% of the patients presented positive for JCV in at least one sample analyzed, 54,5% were positive for BKV, 18,2% for Merkel cell and there was no positive sample for TSV. In GC, 45% showed JCV positivity in at least one analyzed sample, 80% in BKV, and no control participant exhibited positivity for Merkel cell and TSV. There was no difference in the frequency of viral detection among the groups studied in relation to the samples collected, or in relation to age or gender. However, in oral fluid samples there was a higher prevalence of detection for BKV and Merkel cell. We conclude that oral fluids, especially saliva and mouthwash, can be used for the screening of BK e JC; and that HIV positive individuals under antiretroviral treatment do not exhibit higher frequencies of polyomavirus compared to healthy control subjects.

Os poliomavírus compõem uma grande família de vírus que causam infecções primárias geralmente na infância, e se mantem em condições subclínicas. Em situações de imunossupressão podem causar algumas doenças. Os indivíduos com HIV/AIDS frequentemente apresentam deficiência imunológica e por isso podem exibir maior risco de doenças causadas pelos poliomavírus. A utilização da saliva no diagnóstico e acompanhamento de doenças infecciosas tem sido explorado na literatura. As vantagens de usar a saliva para rastreio se pautam especialmente na coleta não invasiva e segurança no manuseio. O presente estudo teve como objetivo, detectar e quantificar o DNA dos poliomavírus BKV, JCV, de células Merkel e TSV, em fluídos orais (saliva, lavado bucal e fluído gengival crevicular) e comparar com a detecção em soro e urina, meios usualmente utilizados para detecção. Foram coletadas 299 amostras de 42 indivíduos, sendo 22 HIV positivos (GE) e 20 pacientes controle (GC). No GE, 63,6% dos pacientes apresentaram positividade para JCV em pelo menos uma amostra analisada, 54,5% foram positivos para BKV, 18,2% para células Merkel e não houve amostra positiva para TSV. No GC, 45% exibiu positividade para o JCV em pelo menos uma amostra analisada, 80% para BKV e nenhuma participante controle exibiu positividade para células Merkel e TSV. Não houve diferença de frequência de detecção viral entre os grupos estudados em relação às amostras coletadas, ou ainda em relação à idade ou sexo. Entretanto, nas amostras de fluídos orais houve maior prevalência de detecção para o BKV e para células Merkel. Concluímos que fluídos orais, especialmente saliva e lavado bucal, podem ser usados para o rastreamento do BK e JC; e que os indivíduos HIV positivos, sob tratamento antirretroviral não exibem frequências maior de poliomavírus, comparativamente a indivíduos controle. / Polyomavirus is one of the large family of viruses that cause primary infections usually in childhood, and can remain subclinical. In immunosuppression may cause some diseases. Individuals with HIV/AIDS often have immune deficiencies and may be at increased risk for diseases caused by polyomaviruses. The use of saliva in the diagnosis and follow-up of infectious diseases has been explored in the literature. The advantages of using saliva for screening are based on non-invasive collection and handling safety. The aim of present study was to detect and quantify the DNA from BKV, JCV, Merkel cell and TSV polyomaviruses in oral fluids (saliva, mouthwash and gingival crevicular fluid) and to compare it with serum and urine detection, the means usually used for detection. A total of 299 samples were collected from 42 individuals, 22 HIV positive (GE) and 20 control patients (GC). In GE, 63,6% of the patients presented positive for JCV in at least one sample analyzed, 54,5% were positive for BKV, 18,2% for Merkel cell and there was no positive sample for TSV. In GC, 45% showed JCV positivity in at least one analyzed sample, 80% in BKV, and no control participant exhibited positivity for Merkel cell and TSV. There was no difference in the frequency of viral detection among the groups studied in relation to the samples collected, or in relation to age or gender. However, in oral fluid samples there was a higher prevalence of detection for BKV and Merkel cell. We conclude that oral fluids, especially saliva and mouthwash, can be used for the screening of BK e JC; and that HIV positive individuals under antiretroviral treatment do not exhibit higher frequencies of polyomavirus compared to healthy control subjects.

Thesis (Ph. D.)--University of Missouri--Columbia, 2003. / "August 2003." Typescript. Vita. Includes bibliographical references (leaves 110-133). Also issued on the Internet.