Infections in the central nervous system pose a considerable challenge to the host. On one hand, a quick and rapid immune response is important to control the infection, while on the other hand, too robust a response can damage the CNS, which has poor regenerative properties. Therefore, nowhere else in the body is such a balance between pro- and anti-inflammatory mediators as important. Mice infected with the coronavirus, mouse hepatitis virus strain J2.2-V-1, are a useful model for understanding the two sides of the immune system. In this neurotropic viral infection, demyelination occurs secondary to the immune response's control of the viral infection. Thus, J2.2-V-1 infection also functions as an infectious animal model for multiple sclerosis (MS). Many arms of the pro-inflammatory immune system have been studied during J2.2-V-1 infection but the anti-inflammatory immune response has not been thoroughly investigated prior to this study. The data demonstrated here represent an in-depth look into the role of regulatory T cells and IL-10 during J2.2-V-1 infection. Specifically, by adoptive transfer of Tregs, I show that there is a relative paucity of Tregs during J2.2-V-1 infection in C57BL/6 mice and their addition decreases clinical scores, demyelination and the T cell response during infection without affecting viral clearance. A RAG1-/- adoptive transfer model demonstrates clinical results consistent with results obtained in B6 mice, while further demonstrating that Tregs function in the draining cervical lymph node by dampening dendritic cell activation and pro-inflammatory chemokine and cytokine release. There is also a relative decrease in T cell proliferation. Thus, Tregs are protective in J2.2-V-1-induced encephalomyelitis and their enhancement is a potential therapy for MS. Additionally, IL-10 is an important anti-inflammatory component of the immune response, as its absence causes increased immunopathology with increased demyelination in J2.2-V-1-infected B6 mice. Through the development of a recombinant J2.2-V-1 virus that produces IL-10, I also demonstrate that increasing the level of IL-10 at the site of infection is protective early in the immune response. Antigen-specific IFN-γ+ CD4 and CD8 T cells produce IL-10 at the height of the inflammation. CD8 T cells require a high level of antigen stimulation and the most recently activated CD69+CD8 T cells express high levels of IL-10. Additionally, this IL-10 expression is transient in both CD4 and CD8 T cells, presumably only by the recently stimulated cells. Through microarray analysis, protein expression and cytolytic assay, I show that IL-10+CD8 T cells are more activated than IL-10-CD8 T cells. Nonetheless, the IL-10 produced is anti-inflammatory and its production in CD8 T cells is protective in J2.2-V-1-infected mice. Thus, the most activated and cytotoxic CD8 T cells self-regulate the immune response through the production of IL-10. Overall, these studies show that the anti-inflammatory component of the immune system is vital to protecting the host from the immunopathology that occurs during J2.2-V-1 virus clearance. Specifically, the addition of Tregs and IL-10 helps ameliorate clinical disease and demyelination. These studies suggest that increasing Tregs and/or increasing the cytokine IL-10 in patients with MS may have therapeutic potential.

Made available in DSpace on 2014-06-11T19:33:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-01-30Bitstream added on 2014-06-13T19:44:12Z : No. of bitstreams: 1 pedrazaordonez_fj_dr_jabo.pdf: 707975 bytes, checksum: 9868dbb427049fb448644457810a5e65 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O BoHV-5 é um alfa herpesvírus neurovirulento, que causa meningoencefalite fatal em bezerros. A morbidade é baixa contrastando com uma alta mortalidade, embora alguns animais possam-se recuperar. Varias pesquisas tem sido desenvolvidas para determinar a patogênese deste tipo de doença. No presente trabalho coelhos experimentalmente infectados com o Herpesvírus Bovino 5 (BoHV-5) foram submetidos a análise imuno-histoquímica e molecular, mediante a real time PCR, para descrever a resposta inflamatória em seis diferentes regiões do seu encéfalo. Todos os animais mostraram sinais neurológicos severos e foram eutanasiados vinte dias após a infecção inicial. Microscopicamente foi descrita uma meningoencefalite não supurativa, caracterizada por meningite, manguitos perivasculares mononucleares e malacia, mas não foram observados corpúsculos de inclusão viral. Os linfócitos T constituíram uma alta percentagem das células mononucleares envolvidas na neuroinflamação. Não foram encontradas diferenças significativas na resposta astrocitária quando comparados o grupo experimental e o grupo controle (p > 0,05). A quantificação viral pela qPCR permitiu achar partículas virais em todas as regiões encefálicas, de todos os animais do grupo experimental, sendo diretamente proporcional a quantidade de vírus e a visualização de lesões histológicas no encéfalo dos coelhos, assim como a imunodetecção do BoHV-5 pela imunohistoquímica. É possível suspeitar de um forte envolvimento do sistema imunitário do hospedeiro que fez a maioria dos animais reagir de maneira diferente ante a mesma quantidade do inóculo viral ministrado / The BoHV-5 is a neurovirulent alpha herpesvirus, which causes fatal meningoencephalitis in calves. The morbidity is low in contrast with a high mortality, although some animals can heal. Several surveys have been developed trying to better understand the pathogenesis of this type of disease. In this study rabbits experimentally infected with bovine herpesvirus 5 (BoHV-5) were subjected to immunohistochemical and molecular analysis by real time PCR, to describe the inflammatory response in six different regions of his brain. All animals showed severe neurological signs and were euthanized twenty days after the initial infection. Microscopically was described a meningoencephalitis characterized by nonsuppurative meningitis, mononuclear perivascular cuffs and malacia, but were not observed viral inclusion corpuscles. T lymphocytes constituted a high percentage of mononuclear cells involved in neuroinflammation and there were no significant differences in astrocyte response when comparing the experimental and control groups (p> 0.05). The viral quantification by qPCR allowed found viral particles in all brain regions of all experimental animals, being directly proportional to the amount of virus and the visualization of lesions in the brain of rabbits, as well as immunodetection of BoHV-5 by immunohistochemistry. It is possible to suspect a strong engagement of the host immune system that made the majority of animals respond differently compared to the same administered amount of viral inoculum

Made available in DSpace on 2014-06-11T19:33:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-02-18Bitstream added on 2014-06-13T19:44:14Z : No. of bitstreams: 1 vasconcelos_ro_dr_jabo.pdf: 1349333 bytes, checksum: 7eaa9b531ee75109ac659bcca081d17c (MD5) / A compreensão do comportamento da microglia frente a uma injúria viral contribui para o entendimento da dimensão da rede de comunicação celular, durante um processo degenerativo ou inflamatório no SNC. Pesquisas que utilizam modelos experimentais com o vírus da estomatite vesicular (VEV) têm colaborado com informações importantes sobre o comportamento e distribuição do agente no encéfalo, e também sobre o papel da resposta imune na resolução ou no agravamento das lesões nervosas. Neste estudo, foi comparada a evolução do quadro neurológico induzido pelo VEV, por meio de técnicas de imunoistoquímca, em cérebros de camundongos. Foi possível observar que o VEV causa severa degeneração e necrose do neurópilo, com lesão direta em neurônios, pois estes mostraram-se claramente positivos para o vírus, por meio da reação de imunoistoquímica no cérebro. A reação astrocitária foi intensa nos animais infectados, porém a densidade destas células reduziu com o aumento da gravidade das lesões. As células residentes (neurônios, astrócitos e microglia) e as células inflamatórias expressaram MIP-1a e, em menor proporção, MIP-1b. A microgliose reativa foi significativa nos animais com sintomatologia clínica. A diversidade morfológica da microglia foi grande, variando desde uma forma fusiforme a uma ramificada e a forma arredondada fagocítica das áreas necróticas. Foi possível observar que existe uma profunda interação entre as células residentes do SNC - neurônios, microglia, astrócitos, endotélio, frente ao estímulo viral. Baseado nos relatos da literatura é importante salientar que os astrócitos mantêm um controle ativo sobre a microglia tanto em repouso quanto ativada, via citocinas/quimiocinas. A densidade aumentada dessas células coincidiu com a redução do número de astrócitos, devido à necrose do neurópilo... / The comprehension of the microglial cell behavior in a viral injury colaborate for the understanding of the dimension of the cellular communication net, during a degenerative or inflammatory process in central nervous system (CNS). Experimental models with the vesicular stomatitis virus (VSV), has contributed with important information about the behavior and distribution of virus in the CNS. Such studies evaluated the role of the immune response in the resolution or in the damage of the nervous lesions. In this study, the evolution of the neurological signals and lesions induced by VSV infection in mice was studied, using imunohistochemical techniques. It was observed that VSV causes severe degeneration and necrosis of the neuropil and direct lesions to the neurons. The neurons were the most intensively stained cells for the virus in the brain. The reactive astrocitosis was intense in the infected animals, but the density of these cells reduced with the increase of the gravity of the lesions. The resident and inflammatory cells expressed MIP-1a and in smaller proportion MIP-1b, in different cellular types (neurons, astrocytes and microglia). The reactive microgliosis was significant in animals with clinical symptomatology and there was a great morphologic microglial diversity, varying from a fusyforme form and ramified form and the fagocitic round form of the around necrotics areas. It was possible to observe that a close interaction exists among the resident cells of SNC (neurons, microglia, astrocytes, endothelial cells) in face of the viral infection. Based on the reports of the literature it is important to point out that the astrocytes maintains an active control on the microglia (in resting or activated cells), through citokines/chemokines. The increased density of microglia coincided with the reduction of the astrocytes number, due to the necrosis of the neuropil... (Complete abstract, access undermentioned eletronic address)

Encephalitis is a matter for serious public health concern because of the high morbidity and mortality associated with many cases. Epidemiological studies have shown that viral encephalitis (VE) is more common than the sum of encephalitis caused by all other pathogens. However, more than 95% of cases have no known cause. Thus, there is a significant need to develop a sensitive method for the diagnosis of these unknown cases. Previous sequence independent amplification (SIA) assays have proved successful in detecting new viruses in many biological samples but not in CSF samples. This may be due to the relatively low sensitivity of most available methods as CSF usually contains lower concentrations of pathogen than most other samples. A known problem with these types of assays is the annealing of the random primers to human DNA which facilitates preferential amplification of background human DNA. Thus, large scale sequencing is usually required to detect a virus, which in turn reduces the detection sensitivity to more than 1000 viral copies/µl, a CSF concentration that is rarely seen in cases of VE.This project was designed to develop a highly sensitive SIA assay for novel nucleic acid identification that could be used in testing CSF samples obtained from patients with neurological diseases of unknown cause. The study started with evaluation of two existing SIA assays commonly used for virus discovery; whole genome amplification (WGA) and random PCR (r-PCR). Sequential modification and adaptation of these methods was carried out to increase their sensitivity. Ultimately, a novel primer (Sa primer) that showed no binding to most human DNA sequences in GenBank was designed and synthesised. Its 3' end was tagged with 6 and 7 random nucleotides generating 2 r-primers; Sa-6 and Sa-7. The sensitivity of the r-primers was checked in a novel assay developed during this project and named Sa-SIA using known concentrations of HCMV and HSV-1. CSF samples from Malawian children were then tested using the developed assay. Results showed that adaptation of the existing WGA and r-PCR assays allowed detection of up to 1300 viral copies/µl. When the novel primers developed in this project were used in a random PCR assay (Sa-r-PCR), it was found that using Sa-6 primer 130, 13, and 1.3 HCMV copies/µl could be detected with 100, 60, and 50% efficiency respectively. When using Sa-7 primer, the same concentrations of virus were detected with 100, 42, and 28.6% efficiency. DNase-1 treatment of the samples pre-extraction resulted in an improvement in viral detection sensitivity in samples with a high background of host DNA. Starting with template concentrations of 11000, 110, 11, and 1.1 HSV-1 copies/µl, viral detection efficiency was increased from 33.3, 10, 0, and 0% to 92, 55.6, 16.7, and 0% respectively when pre-extraction DNase-1 treatment preceded Sa-r-PCR using Sa-6 primer. The final developed assay (Sa-SIA) consisted of centrifugation, DNase-1 treatment, DNA extraction, Sa-r-PCR using Sa-6 and Sa primers, gel electrophoresis, band excision, cloning, small scale sequencing (sequencing of ≤ 20 positive clones from one constructed DNA library), and bioinformatics. It had a detection sensitivity of 1.3-11 viral copies/µl. When this assay was applied to stored CSF samples, one 448bp sequence was identified which gave 96% coverage with 81% identity to Torque teno midi virus-1 and 93% coverage with 81% identity to small anellovirus-2. A 236bp sequence from another CSF sample showed 66% coverage with 97% homology to an unclassified sequence previously identified in a viral genomic survey of stool sample in an earlier published study. In conclusion, the standardised method had been shown to detect 1.3 to 11 viral copies/µl of two viruses; HCMV and HSV-1. The detection of these viruses was achieved with only small scale sequencing. Application of this method to CSF samples has shown promising results. However, this method could be followed by more advanced post amplification analyses such as next generation sequencing.

Orientador: Tereza Cristina Cardoso Silva / Banca: Roberto Gameiro de Carvalho / Banca: Andréa Fontes Garcia / Banca: Ana Carolina Borsanelli / Banca: Jamila Cristina Baptistella / Resumo: O herpes vírus bovino 5 (HVB-5) é um agente infeccioso pertencente a família Herpesviridae, sub-família Alphaherpesvirinae e gênero Varicellovirus. É um vírus neurotrópico que causa doenças neurológicas principalmente em animais jovens em todo mundo, especialmente nos países Sul-americanos, resultado em significantes perdas econômicas. A infecção pelo herpesvírus bovino 5 em gado jovemestá associado a doença neurológica que é, usualmente, fatal, sendo um ótimo modelo para estudar a patogênese da meningoencefalite induzida por vírus. O HVB5 replica na mucosa nasal, e invadesistema nervoso central (SNC), principalmente por meio do sistema olfatório. A resposta imune inata desencadeada pelo hospedeiro frente à replicação do vírus por meio da via olfativa não é totalmente entendida. Estudos verificaram as variações nos níveis de expressão de receptores Toll-Like (TLRs) em diferentes regiões do sistema nervoso central bovino durante a infecção aguda e reativação de bovinos infectados por HVB-1 e HVB-5-.Uma nova perspectiva para entender a relação do patógeno e o hospedeirorelacionando os microRNAs(miRNAs) que interagem com a resposta imune inatadurante infecções virais neurotrópicas. / Abstract: Bovine herpes virus 5 (BHV-5) is an infectious agent belonging to the family Herpesviridae, subfamily Alphaherpesvirinae and genus Varicellovirus. It is a neurotropic virus that causes neurological diseases mainly in young animals worldwide, especially in the South American countries, resulting in significant economic losses. Bovine herpesvirus 5 infection in young cattle is associated with neurological disease, which is usually fatal and is a good model for studying the pathogenesis of virus-induced meningoencephalitis. The BHV5 replicates in the nasal mucosa, and invades the central nervous system (CNS), mainly through the olfactory system. The innate immune response triggered by the host against virus replication via the olfactory route is not fully understood. Studies have found variations in the levels of Toll-Like receptor (TLR) expression in different regions of the bovine central nervous system during acute infection and reactivation of BoHV-1 and BoHV-5 infected bovines. A new perspective to understand the relationship of the pathogen and the host relating the microRNAs (miRNAs) that interact with the innate immune response during neurotropic viral infections. / Doutor

Orientador: Antonio Carlos Alessi / Coorientador: Noeme Sousa Rocha / Banca: Gisele Fabrino Machado / Banca: Mary Suzan Varaschin / Banca: Rosemeri de Oliveira Vasconcelos / Banca: Luiz Carlos Marques / Resumo: O BoHV-5 é um alfa herpesvírus neurovirulento, que causa meningoencefalite fatal em bezerros. A morbidade é baixa contrastando com uma alta mortalidade, embora alguns animais possam-se recuperar. Varias pesquisas tem sido desenvolvidas para determinar a patogênese deste tipo de doença. No presente trabalho coelhos experimentalmente infectados com o Herpesvírus Bovino 5 (BoHV-5) foram submetidos a análise imuno-histoquímica e molecular, mediante a real time PCR, para descrever a resposta inflamatória em seis diferentes regiões do seu encéfalo. Todos os animais mostraram sinais neurológicos severos e foram eutanasiados vinte dias após a infecção inicial. Microscopicamente foi descrita uma meningoencefalite não supurativa, caracterizada por meningite, manguitos perivasculares mononucleares e malacia, mas não foram observados corpúsculos de inclusão viral. Os linfócitos T constituíram uma alta percentagem das células mononucleares envolvidas na neuroinflamação. Não foram encontradas diferenças significativas na resposta astrocitária quando comparados o grupo experimental e o grupo controle (p > 0,05). A quantificação viral pela qPCR permitiu achar partículas virais em todas as regiões encefálicas, de todos os animais do grupo experimental, sendo diretamente proporcional a quantidade de vírus e a visualização de lesões histológicas no encéfalo dos coelhos, assim como a imunodetecção do BoHV-5 pela imunohistoquímica. É possível suspeitar de um forte envolvimento do sistema imunitário do hospedeiro que fez a maioria dos animais reagir de maneira diferente ante a mesma quantidade do inóculo viral ministrado / Abstract: The BoHV-5 is a neurovirulent alpha herpesvirus, which causes fatal meningoencephalitis in calves. The morbidity is low in contrast with a high mortality, although some animals can heal. Several surveys have been developed trying to better understand the pathogenesis of this type of disease. In this study rabbits experimentally infected with bovine herpesvirus 5 (BoHV-5) were subjected to immunohistochemical and molecular analysis by real time PCR, to describe the inflammatory response in six different regions of his brain. All animals showed severe neurological signs and were euthanized twenty days after the initial infection. Microscopically was described a meningoencephalitis characterized by nonsuppurative meningitis, mononuclear perivascular cuffs and malacia, but were not observed viral inclusion corpuscles. T lymphocytes constituted a high percentage of mononuclear cells involved in neuroinflammation and there were no significant differences in astrocyte response when comparing the experimental and control groups (p> 0.05). The viral quantification by qPCR allowed found viral particles in all brain regions of all experimental animals, being directly proportional to the amount of virus and the visualization of lesions in the brain of rabbits, as well as immunodetection of BoHV-5 by immunohistochemistry. It is possible to suspect a strong engagement of the host immune system that made the majority of animals respond differently compared to the same administered amount of viral inoculum / Doutor

Le danio zébré est un modèle bien établi pour étudier la biologie du développement des vertébrés. Ses larves transparentes sont favorables à des approches de microscopie non invasive, qui permettent de réaliser des observations à l’échelle d’un individu entier à des niveaux de résolution cellulaire et subcellulaire. Ces atouts font du danio zébré un excellent modèle pour étudier les infections virales in vivo. Au cours de mon projet, j’ai etudié l’entrée et la colonisation du système nerveux central (SNC) par le virus Sindbis (SINV) dans le modèle danio zébré. Mon projet présentait plusieurs axes: 1) développer un modèle d’infection du virus Sindbis chez le danio zébré, 2) caractériser l’invasion du SNC par le virus par des techniques d’imagerie à haute résolution, 3) définir la voie d’entrée du virus dans le SNC, 4) évaluer la dynamique de la réponse immunitaire innée par l’étude de la réponse interféron. Le suivi de la propagation du virus a été rendu possible par l’utilisation d’un ARN viral recombinant exprimant la protéine fluorescente verte ‘GFP’. L’utilisation de cette construction m’a permis de caractériser la progression de SINV chez le danio zébré et d’identifier les organes/tissus cibles que sont le vitellus, le foie, le cœur et enfin, le cerveau. Les données rassemblées jusqu'à présent m’ont aussi permis d’identifier le mécanisme par lequel SINV se propage vers le cerveau: le virus se propage par un transport axonal du system nerveux périphérique vers le SNC. Dans le cadre de la réponse immunitaire au niveau cellulaire, j’ai pu observer le rôle joué par les leucocytes, en particulier les neutrophiles, comme cellules productrices d'interféron. / The zebrafish (Danio rerio) is an important model organism, particularly for studies of development and more recently host pathogen interactions. As opposed to other vertebrate model organisms, its optical clarity and ease of genetic manipulations allow to visualize highly dynamic cellular processes in vivo at the whole organism scale. These assets make the zebrafish a perfect model for the study of viral infections in vivo, such as those caused by neurotropic viruses. The aim of this project has been to gain insights in some of the interactions that determine encephalitis, by characterizing the neurotropic Sindbis virus (SINV). This Thesis project has consisted therefore in: 1) the development of a SINV infection model in zebrafish larvae, 2) the characterization of SINV neuroinvasion upon its inoculation in the bloodstream, thanks to the use of high resolution microscopy, 3) the study of SINV mechanism of entry in the CNS, 4) the characterization of the innate immune response, both at the whole organism and organ specific level. Thanks to the use of a SINV recombinant strain, engineered to express the green fluorescent protein “GFP” in infected cells upon viral replication, we have been able to follow the onset and the progression of the infection. We have suggested infection of peripheral neurons and subsequent axonal transport to the CNS as SINV entry mechanism. At the cellular level, we have identified neutrophils as the main IFN producing cells.

Infecções no sistema nervoso central (SNC) causadas por microrganismos desencadeiam sintomas de moderados a severos, dependendo da região atingida, podendo ser designadas como encefalites ou meningites. Os vírus são os agentes mais comuns nestas infecções. Os agentes virais responsáveis por essas enfermidades que apresentam maior incidência na população mundial são certos herpesvírus, flavivírus, influenza A, enterovírus e vírus da caxumba. Entretanto, essa prevalência varia de acordo com a população, estado imunológico do indivíduo, idade e região estudada. Embora existam dados bem estabelecidos da etiologia dessas doenças em alguns países, ainda há uma carência de informação no que diz respeito à etiologia dessas moléstias no Brasil. Assim, informações mais precisas em relação à prevalência desses agentes em nosso meio são necessárias para o desenvolvimento e aplicação de métodos de diagnósticos mais rápidos e eficientes. Neste trabalho, foram analisadas 120 amostras de liquido cefalorraquidiano (LCR), procedentes de dois centros da cidade de São Paulo (Irmandade Santa Casa de Misericórdia e Hospital das Clínicas da Faculdade de medicina da Universidade de São Paulo), as quais foram submetidas à reação em cadeia de polimerase para o herpesvirus simples 1 e 2 (HSV 1 e 2), vírus da varicela zoster (VZV), herpesvirus humano 6 (HHV-6), influenza A (FLUA), enterovírus, vírus da caxumba, poliomavírus vírus BK (BKV) e vírus JC (JCV) para flavivírus. Do total, 44 amostras (36,7%) apresentaram resultado positivo para algum dos vírus analisados no âmbito desta pesquisa, sendo 15 (12,5%) para poliomavírus BKV, 2 (1,7%) para poliomavírus JCV, 21 (17,5%) para HSV1 e 2, 5 (4,2%) foram positivos para BKV e HSV1 e 2 (coinfecção) e 1 (0,8%) para vírus Epstein-Barr (EBV). Uma parte das amostras negativas foi submetida a sequenciamento direto de nova geração (n=8 amostras), resultando em amostras positivas para vírus (vírus simio 40), protozoários e bactérias. Este estudo mostrou que infelizmente, menos de 50% das encefalites e meningites assépticas puderam ser relacionadas a algum agente viral. Houve uma alta prevalência de HSV no material estudado, de acordo com o esperado, mas a presença de poliomavírus no LCR destes indivíduos foi acima da observada na literatura. Esses, bem como os resultados de sequenciamento direto e sua associação a etiologia das encefalites e meningites, devem ser interpretados com cautela. / Central nervous system (CNS) infections caused by microorganism trigger moderate to severe symptoms, depending on the region affected and may be referred as encephalitis or meningitis. Viruses are the most common agents in these infections. The viral agents responsible for these diseases with highest incidence worldwide are certain herpesviruses, flaviviruses, influenza A, enteroviruses, and mumps virus. However, their prevalence vary according to the population, immunological state of the individual, age and region studied. Although there are well-established data on the etiology of these diseases in some countries, there is little information regarding the etiology of these diseases in Brazil. Thus, data regarding the prevalence of these agents in our environment is necessary for the development and application of faster and more efficient diagnostic methods. In this study, 120 cerebrospinal fluid (CSF) samples from two centers of the city of São Paulo (Hospital Santa Casa de Misericordia and Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo) were investigated by PCRs for herpes simplex virus (HSV 1 and 2), varicela zoster virus (VZV), human herpesvirus 6 (HHV6), influenza A, enterovirus, mumps virus, polyomavirus BK virus and JC virus and flaviviruses. From these, 44 samples (36.7%) presented positive result for one of the viruses analyzed, being 15 (12.5%) for polyomavirus BKV, 2 (1.7%) for polyomavirus JCV, 21 (17.5%) for HSV 1 and 2, 5 (4.2%) samples were positive for BKV and HSV1 and 2 (coinfection) and 1 (0.8%) for Epstein-Barr virus (EBV). A part of the negative samples (n=8) were submitted to next generation direct sequencing and revealed the presence of agents as viruses (simian virus 40), protozoa and bacteria. This study showed that unfortunately, less than 50% of the aseptic encephalitis and meningitis could be related to some viral agent. It was found high prevalence of HSV, as expected, but the presence of polyomavirus in the CSF of these individuals was higher than that observed in the literature. These results, as well as direct sequencing results and its relationship to the etiology of encephalitis and meningitis should be interpreted with caution.

Infecções no sistema nervoso central (SNC) causadas por microrganismos desencadeiam sintomas de moderados a severos, dependendo da região atingida, podendo ser designadas como encefalites ou meningites. Os vírus são os agentes mais comuns nestas infecções. Os agentes virais responsáveis por essas enfermidades que apresentam maior incidência na população mundial são certos herpesvírus, flavivírus, influenza A, enterovírus e vírus da caxumba. Entretanto, essa prevalência varia de acordo com a população, estado imunológico do indivíduo, idade e região estudada. Embora existam dados bem estabelecidos da etiologia dessas doenças em alguns países, ainda há uma carência de informação no que diz respeito à etiologia dessas moléstias no Brasil. Assim, informações mais precisas em relação à prevalência desses agentes em nosso meio são necessárias para o desenvolvimento e aplicação de métodos de diagnósticos mais rápidos e eficientes. Neste trabalho, foram analisadas 120 amostras de liquido cefalorraquidiano (LCR), procedentes de dois centros da cidade de São Paulo (Irmandade Santa Casa de Misericórdia e Hospital das Clínicas da Faculdade de medicina da Universidade de São Paulo), as quais foram submetidas à reação em cadeia de polimerase para o herpesvirus simples 1 e 2 (HSV 1 e 2), vírus da varicela zoster (VZV), herpesvirus humano 6 (HHV-6), influenza A (FLUA), enterovírus, vírus da caxumba, poliomavírus vírus BK (BKV) e vírus JC (JCV) para flavivírus. Do total, 44 amostras (36,7%) apresentaram resultado positivo para algum dos vírus analisados no âmbito desta pesquisa, sendo 15 (12,5%) para poliomavírus BKV, 2 (1,7%) para poliomavírus JCV, 21 (17,5%) para HSV1 e 2, 5 (4,2%) foram positivos para BKV e HSV1 e 2 (coinfecção) e 1 (0,8%) para vírus Epstein-Barr (EBV). Uma parte das amostras negativas foi submetida a sequenciamento direto de nova geração (n=8 amostras), resultando em amostras positivas para vírus (vírus simio 40), protozoários e bactérias. Este estudo mostrou que infelizmente, menos de 50% das encefalites e meningites assépticas puderam ser relacionadas a algum agente viral. Houve uma alta prevalência de HSV no material estudado, de acordo com o esperado, mas a presença de poliomavírus no LCR destes indivíduos foi acima da observada na literatura. Esses, bem como os resultados de sequenciamento direto e sua associação a etiologia das encefalites e meningites, devem ser interpretados com cautela. / Central nervous system (CNS) infections caused by microorganism trigger moderate to severe symptoms, depending on the region affected and may be referred as encephalitis or meningitis. Viruses are the most common agents in these infections. The viral agents responsible for these diseases with highest incidence worldwide are certain herpesviruses, flaviviruses, influenza A, enteroviruses, and mumps virus. However, their prevalence vary according to the population, immunological state of the individual, age and region studied. Although there are well-established data on the etiology of these diseases in some countries, there is little information regarding the etiology of these diseases in Brazil. Thus, data regarding the prevalence of these agents in our environment is necessary for the development and application of faster and more efficient diagnostic methods. In this study, 120 cerebrospinal fluid (CSF) samples from two centers of the city of São Paulo (Hospital Santa Casa de Misericordia and Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo) were investigated by PCRs for herpes simplex virus (HSV 1 and 2), varicela zoster virus (VZV), human herpesvirus 6 (HHV6), influenza A, enterovirus, mumps virus, polyomavirus BK virus and JC virus and flaviviruses. From these, 44 samples (36.7%) presented positive result for one of the viruses analyzed, being 15 (12.5%) for polyomavirus BKV, 2 (1.7%) for polyomavirus JCV, 21 (17.5%) for HSV 1 and 2, 5 (4.2%) samples were positive for BKV and HSV1 and 2 (coinfection) and 1 (0.8%) for Epstein-Barr virus (EBV). A part of the negative samples (n=8) were submitted to next generation direct sequencing and revealed the presence of agents as viruses (simian virus 40), protozoa and bacteria. This study showed that unfortunately, less than 50% of the aseptic encephalitis and meningitis could be related to some viral agent. It was found high prevalence of HSV, as expected, but the presence of polyomavirus in the CSF of these individuals was higher than that observed in the literature. These results, as well as direct sequencing results and its relationship to the etiology of encephalitis and meningitis should be interpreted with caution.

Japanese encephalitis virus (JEV) causes viral encephalitis in new born and young adults that is prevalent in different parts of India and other parts of South East Asia with an estimated 6000 deaths per year. JEV is a single stranded RNA virus that belongs to the Flavivirusgenus of the family Flaviviridae. It is a neurotropic virus which infects the central nervous system (CNS). The virus follows a zoonotic life-cycle involving mosquitoes and vertebrates, chiefly pigs and ardeid birds, as amplifying hosts. Humans are dead end hosts. After entry into the host following a mosquito bite, JEV infection leads to acute peripheral leukocytosis in the brain and damage to Blood Brain Barrier (BBB). The exact role of the endothelial cells during CNS infection is still unclear. However, disruption of this endothelial barrier has been shown to be an important step in entry of the virus into the brain. Humoral and cell mediated immune responses during JEV infection have been intensively investigated. Previous studies from our lab have shown the activation of cytotoxic T-cells (CTLs) upon JEV infection. MHC molecules play pivotal role in eliciting both adaptive (T-cells) and innate (NK cells) immune response against viral invasion. Many viruses such as HIV, MCMV, HCMV, AdV and EBV have been found to decrease MHC expression upon infection. On the contrary, flaviviruses like West Nile Virus (WNV) have been found to increase MHC-I and MHC-II expression. More recently, data from our lab has shown that JEV infection can lead to upregulation of mouse non-classical MHC class Ib molecules like Qb1, Qa1 and T-10 along with classical MHC molecules. Non-classical MHC molecules are important components of the innate and adaptive immune systems. Non-classical MHC molecules differ from their classical MHC class I counterparts by their limited polymorphism, restricted tissue distribution and lower levels of cell surface expression. Human classical MHC class I molecules are HLA-A, -B and –C while non-classical MHC Class Ib molecules are HLA-E, -G and –F. HLA-E, the human homologue of the mouse non-classical MHC molecule, Qa-1b has been shown to be the ligand for the inhibitory NK, NKG2A/CD94 and may bridge innate and adaptive immune responses. In this thesis, we have studied the expression of human classical class I molecules HLA-A, -B, -C and the non-classical HLA molecule, HLA-E in immortalized human brain microvascular endothelial cells (HBMEC), human endothelial like cell line ECV304 (ECV), human glioblastoma cell line U87MG and human foreskin fibroblast cells (HFF). We observed an upregulation of classical HLA molecules and HLA-E mRNA in endothelial and fibroblast cells upon JEV infection. This mRNA increase also resulted in upregulation of cell surface classical HLA molecules and HLA-E in HFF cells but not in both the human endothelial cell lines, ECV and HBMECs. Release of soluble classical HLA molecules upon cytokine treatment has been a long known phenomenon. Recently HLA-E has also been shown to be released as a 37 kDa protein from endothelial cells upon cytokine treatments. Our study suggests that JEV mediated upregulation of classical HLA and HLA-E upregulation leads to release of both Classical HLA molecules and HLA-E as soluble forms in the human endothelial cell lines, ECV and HBMEC. This shedding of sHLA-E from human endothelial cells was found to be mediated by matrix metalloproteinase (MMP) proteolytic activity. MMP-9, a protease implicated in release of sHLA molecules was also found to be upregulated upon JEV infection only in endothelial cell lines but not in HFF cells. Our study provides evidence that the JEV mediated solubilisation of HLA-E could be mediated by MMP-9. Further, we have tried to understand the role of the MAPK pathway and NF-κB pathway in the process of HLA-E solubilisation by using specific inhibitors of these pathways during JEV infection of ECV cells. Our data suggests that release of sHLA-E is dependent on p38 and JNK pathways while ERK 1/2 and NF-κB pathway only had a minor role to play in this process. Treatment of endothelial cells with TNF-α, IL-1β and IFN-γ is known to result in release of sHLA-E. In addition to TNF-α and IFNtreatment, we observed that activating agents like poly (I:C), LPS and PMA also resulted in the shedding of sHLA-E from ECV as well as U87MG but not from HFF cells. Treatment of endothelial cells with IFN-β, a type-I interferon also led to release of sHLA-E. IFN-γ, a type II interferon and TNF-α are known to show additive increase in solubilisation of HLA-E. We studied the interaction between type I interferon, IFN-β and TNF-α with regard to shedding of sHLA- E. Both IFNand TNF, when present together caused an additive increase in the shedding of sHLA-E. These two cytokines were also found to potentiate the HLA-E and MMP-9 mRNA expression. Hence, our data suggest that these two cytokines could be working conjunctly to release HLA-E, when these two cytokines are present together as in the case of virus infection of endothelial cells. HLA-E is known to be a ligand for NKG2A/CD94 inhibitory receptors present on NK and a subset of T cells. Previous reports have suggested that NKG2A/CD94 mediated signaling events could inhibit ERK 1/2 phosphorylation leading to inhibition of NK cell activation. IL-2 mediated ERK 1/2 phosphorylation is known to play a very important role in maintenance and activation of NK cells. We studied the effects of sHLA-E that was released, either by JEV infection or IFN-γ treatment on IL-2 mediated ERK 1/2 phosphorylation in two NK cell lines, Nishi and NKL. The soluble HLA-E that was released upon JEV infection was functionally active since it inhibited IL-2 and PMA induced phosphorylation of ERK 1/2 in NKL and Nishi cells. Virus infected or IFN-γ treated ECV cell culture supernatants containing sHLA-E was also found to partially inhibit IL-2 mediated induction of CD25 molecules on NKL cells. CD25 is a component of the high affinity IL-2 receptor and hence could play an important role in proliferation and activation of NK cells. sHLA-E was also found to inhibit IL-2 induced [3H]-thymidine incorporation suggesting that, similar to cell surface expressed HLA-E, sHLA-E could also inhibit the proliferation and activation of NK cells. In summary, we found that establishment of JEV infection and production of cytokines like IFN-β, TNF-α, IL-6 along with MMP-9 in human endothelial cells. These cytokines may also indirectly lead to the reported damage and leukocyte infiltration across infected and uninfected vicinal endothelial cells. The increased surface expression of HLA-E in fibroblast and release of sHLA and sHLA-E molecules from endothelial cells may have an important immunoregulatory role. HLA-E is an inhibitory ligand for NKG2A/CD94 positive CD8+ T and NK cells. Hence our finding that sHLA-E can inhibit NK cell proliferation suggests an immune evasive strategy by JEV.