Made available in DSpace on 2015-07-22T20:50:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-03-25 / A infecção pelo herpesvírus humano tipo 8 (HHV-8) e suas correlações clínicas não foram até o presente bem caracterizadas em indivíduos recém-infectados pelo HIV. Esse estudo avalia a prevalência e correlações clínicas da infecção pelo HHV-8 em uma coorte de 228 indivíduos recém-infectados pelo HIV (vírus da imunodeficiência humana), além de estudar a incidência desta infecção após um ano de acompanhamento. As sorologias para HHV-8 foram realizadas através de imunofluorescência indireta para antígenos latentes e líticos. Encontrou-se prevalência de 25,9% (59/228) no início do acompanhamento. No modelo de análise univariada, foram encontradas associações estatisticamente significantes com sexo masculino (p=0,05), transmissão entre homens que fazem sexo com homens (p=0,023), hepatite B (p=0,009), sífilis (0,034) e etnia negra (p=0,021). No modelo multivariado permaneceram as associações com modo de transmissão, hepatite B e etnia negra. Não foram evidenciadas diferenças nas medianas da contagem de linfócitos T CD4+ e na carga viral do HIV de acordo com positividade para o HHV-8. Em termos de incidência, foram observadas 23/127 (18,1%) soroconversões na coorte após 1 ano de acompanhamento. A partir deste estudo pode-se concluir que o HHV-8 é altamente prevalente em indivíduos recém-infectados pelo HIV. Além disso, as correlações encontradas entre o HHV-8 e outras infecções sexualmente transmissíveis corroboram a teoria de que estas infecções compartilham modos de trasmissão comuns. / Background: Human herpesvirus 8 (HHV-8) is the etiological agent for Kaposi’s sarcoma, which occurs especially in HIV-infected subjects. HHV-8 infection and its clinical correlates have not been well characterized in recently HIV-1-infected individuals. Methods: We assessed the HHV-8 seroprevalence, clinical correlates, and incidence after one year of follow-up in a cohort of 228 recently HIV-1-infected individuals using indirect immunofluorescence assay. Results: The prevalence of HHV-8 infection at the time of cohort enrollment was 25.9% (59/228). In the univariate model, there were significant associations with male gender (p=0.05), black ethnicity (p=0.021), men who have sex with men (MSM) practice (p=0.023), and previous hepatitis B virus (p=0.009) and syphilis (p=0.034) infections. In the multivariate model we could still demonstrate association with MSM, hepatitis B, and black ethnicity. No differences in mean CD4+ cell counts or HIV viral load according to HHV-8 status were found. In terms of incidence, there were 23/127 (18.1%) seroconversions in the cohort after one year. Conclusions: HHV-8 is highly prevalent among recently HIV-1-infected subjects. Correlations with other sexually transmitted infections suggest common transmission routes. / TEDE / BV UNIFESP: Teses e dissertações

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Human Herpesvirus 6A (HHV-6A) and 6B (HHV-6B) are ubiquitous betaherpesviruses. Both viruses are associated with a variety of adult disorders including neurological disorder, such as multiple sclerosis and chronic fatigue syndrome. HHV-6 viruses are capable of establishing latency by integration into the telomeres of the host chromosome and are transmitted in a Mendelian manner in approximately one percent of the population. To date little is known about the immunological and neurological consequences of HHV-6 inheritance. This study focused on a unique population of individuals that inherited HHV-6 and present with chronic fatigue-like symptoms, including hypersomnia, generalized fatigue, headache, and short term and long term memory impairment. The central hypothesis of this study was that active replication of HHV-6 correlates with patient symptoms. To address this aim we first looked at the reactivation of integrated HHV-6 in vitro by inducing viral replication with epigenetic modifiers trichostatin A (TSA), valproic acid, sodium butyrate, and carbamazepine, and found TSA to be an effective method of inducing reactivation of HHV-6 from its integrated form. Additionally, a reactivated HHV-6A virus isolated from a patient with inherited HHV-6 was fully sequenced and the nucleotide and amino acid sequence was compared to that of fully sequenced HHV-6 laboratory strains, as well as the inherited virus. The reactivated virus was found to be very similar to the HHV-6A GS strain; however, there was some divergence at the right end of the viral genome and regions of the genome that do not contain herpesvirus core genes. Interestingly, the sequenced reactivated virus was found to differ from the HHV-6 virus which was inherited. Finally, HHV-6 replication was assessed by performing reverse transcriptase PCR assay for the viral glycoprotein U100 in patients receiving antiviral treatment. Results indicated that short term antiviral treatment was insufficient to abrogate viral replication, while treatment of six weeks or longer eliminated viral mRNA in patient blood samples. Furthermore, sequencing of the viral mRNA and inherited viral DNA indicate that the source of the mRNA detected in patient blood samples was an exogenously acquired HHV-6 virus, as the U100 glycoprotein sequences were not identical. Together these studies indicate that although HHV-6 can be reactivated from its integrated form, individuals in this unique population harbored an exogenous HHV-6 virus, in addition to the inherited virus; we termed this condition inherited herpesvirus syndrome. The fact that these individuals are able to acquire exogenous HHV-6 viruses suggest that there may be some level of immune tolerance or immune dysfunction; we suggest that further studies focus on uncovering the immune response to HHV-6 in individuals with an inherited form of the virus.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第22359号 / 医博第4600号 / 新制||医||1042(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 長尾 美紀, 教授 滝田 順子, 教授 河本 宏 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

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Desde a descoberta do herpes vírus humano tipo 8 (HHV-8) como o agente etiológico do sarcoma de Kaposi (SK) nas suas diferentes formas clínico-epidemiológicas, vários estudos vêm sendo conduzidos com o intuito de determinar as vias de transmissão desse vírus em populações endêmicas e de risco epidemiológico. Em regiões endêmicas, a transmissão viral foi relacionada à transmissão horizontal de mães para filhos e entre irmãos e a sexual principalmente, nos casos de SK/aids. Com o objetivo de determinar segmentos do genoma viral em fluídos biológicos e consequentemente seu potencial infectante foi conduzido o presente trabalho. Foram avaliados quanto à presença de segmentos localizados em posições estratégicas do genoma do HHV-8 em sangue, saliva e urina de 76 pacientes com SK/aids, 19 pacientes com HIV/aids, 4 casos de SK clássico e 11 indivíduos sadios (HIV-soronegativos, sem SK). Foram utilizadas as técnicas de PCR "nested" para as ORF K1, ORF 25, ORF 26, ORF K8.1 e ORF 73 em DNA extraído de material de biópsia de lesão de SK (controle positivo), células do sangue periférico, saliva e urina. Os resultados de PCR positivo para o HHV-8 foram analisados quanto a variáveis epidemiológicas, clínicas e laboratoriais. Foram consideradas como variáveis: sexo, cor, origem étnica, tempo de infecção por HIV e de acompanhamento do SK, terapia ARV e para SK, contagem de células CD4+ e sorologia para o HHV-8 (IFI-LANA e IFI-Lítico). Os testes estatísticos de regressão logística e de razão de chances foram usados para detectar as associações estatisticamente significantes entre as PCRs positivas e as variáveis estudadas nos grupos SK/aids e HIV/aids. Os subtipos do HHV-8 foram também determinados pela técnica de PCR-RFLP da ORF K1 (VR1). Os resultados obtidos mostraram a detecção de DNA/HHV-8 em 80,2% do material de biópsia, 69,7% no sangue, 59,2% na saliva e 21,0% na urina de pacientes com SK/aids. No grupo HIV/aids, a PCR para o HHV-8 resultou positiva em 47,4% dos casos no sangue e em 26,3% na saliva e urina. Já no grupo SK clássico 100% das biópsias e salivas resultaram PCR positiva, 67% do sangue e 33% das urinas. A avaliação sorológica revelou 73,3% de reatividade para IFI-LANA e 85,3% para a IFI-Lítico no grupo SK/aids, enquanto o grupo HIV/aids mostrou reatividade de 15,8% para IFI-LANA e 47,4% para IFI-Lítico; todos os pacientes apresentaram resultados reagentes nas duas sorologias para o HHV-8 no grupo de SK clássico. No grupo controle sadio não houve reatividade na sorologia para o HHV-8, com exceção de um caso, que mostrou ser reagente na IFI-LANA. Foi possível realizar a subtipagem do HHV-8 em amostras de 69 pacientes, sendo detectadas 27 cepas do subtipo A, 13 do subtipo B, 28 do subtipo C e 1 do subtipo E. Após as análises estatísticas foi verificado que as PCRs que identificam as regiões ORF 26, ORF K8.1 e ORF 73 foram as que apresentaram melhor desempenho na identificação de DNA/HHV-8. Houve associação entre a reatividade de IFI-Lítico e a presença do vírus no sangue periférico, assim como a reatividade para IFI-LANA e a detecção de DNA/HHV-8 na saliva. Houve uma tendência dos subtipos B e C de HHV-8 serem detectados em pacientes com infecção profunda ou disseminada de SK. Estes resultados sugerem que a boca pode ser um sítio de latência da infecção por HHV-8 e confirmam a atuação de sangue, saliva e urina como fluídos potencialmente infectantes. / Since the discovery of the human herpesvirus 8 (HHV-8) as the etiological agent of Kaposi’s sarcoma (KS), several studies have been conducted in order to determine routes of virus transmission, mostly in endemic and at risk populations. The main of the present study was to determine target segments of the HHV-8 genoma and consequently infected bodily fluids. DNA sequences of ORF K1, ORF 25, ORF 26, ORF K8.1 and ORF 73 strategically localized in viral genoma were searched using nested PCR techniques in KS lesions (positive control), blood, saliva, and urine from 76 KS/aids patients, 19 HIV/aids patients, 4 classic KS patients, and among 11 healthy individuals (HIV-1 seronegative, without KS). HHV-8 subtypes were determined by PCR-RFLP of the ORF K1 (VR1), and HHV-8 antibodies by IFA-LANA and IFA-Lytic assays. The results obtained were analyzed according to epidemiological, clinical and laboratorial data, and the c2 test, logistic regression and odds ratio were applied to identify statistical association among variables in KS/aids and HIV/aids groups. The results obtained showed HHV-8 DNA in 80.2% of biopsies, 69.7% of blood, 59.2% of saliva, and 21% of urines from KS/aids group. Among HIV/aids patients, 47.4% resulted PCR positive in blood, 26.3% in saliva and urine. In classic KS cases, all biopsies and saliva resulted PCR positive, 67% in blood, and 33% in urine. The serology in KS/aids group showed 73.3% frequency of anti-latent antibodies, and 85.3% frequency of anti-lytic antibodies, while in HIV/aids group the frequencies were 15.8% and 47.4%, respectively. All classic KS cases resulted HHV-8 seroposite, while all individuals from control group resulted HHV-8 seronegative. Molecular characterization of 69 HHV-8 strains disclosed: 27 of subtype A, 13 of subtype B, 28 of subtype C, and 1 of subtype E. The ORF 26, ORF K8.1 and ORF 73 were the best segments for identifying HHV-8 DNA in bodily fluids. It was observed an association between antibodies to lytic antigens and the presence of HHV-8 in blood, and antibodies to latent antigens and the detection of HHV8 DNA in saliva of KS/aids patients. Indeed, HHV-8 subtypes B and C were detected mostly in disseminated KS cases. Taken together, the results obtained suggest that the mouth could be one site of HHV-8 latency, and confirm that blood, saliva and urine were potentially infectious bodily fluids.

Desde a descoberta do herpes vírus humano tipo 8 (HHV-8) como o agente etiológico do sarcoma de Kaposi (SK) nas suas diferentes formas clínico-epidemiológicas, vários estudos vêm sendo conduzidos com o intuito de determinar as vias de transmissão desse vírus em populações endêmicas e de risco epidemiológico. Em regiões endêmicas, a transmissão viral foi relacionada à transmissão horizontal de mães para filhos e entre irmãos e a sexual principalmente, nos casos de SK/aids. Com o objetivo de determinar segmentos do genoma viral em fluídos biológicos e consequentemente seu potencial infectante foi conduzido o presente trabalho. Foram avaliados quanto à presença de segmentos localizados em posições estratégicas do genoma do HHV-8 em sangue, saliva e urina de 76 pacientes com SK/aids, 19 pacientes com HIV/aids, 4 casos de SK clássico e 11 indivíduos sadios (HIV-soronegativos, sem SK). Foram utilizadas as técnicas de PCR "nested" para as ORF K1, ORF 25, ORF 26, ORF K8.1 e ORF 73 em DNA extraído de material de biópsia de lesão de SK (controle positivo), células do sangue periférico, saliva e urina. Os resultados de PCR positivo para o HHV-8 foram analisados quanto a variáveis epidemiológicas, clínicas e laboratoriais. Foram consideradas como variáveis: sexo, cor, origem étnica, tempo de infecção por HIV e de acompanhamento do SK, terapia ARV e para SK, contagem de células CD4+ e sorologia para o HHV-8 (IFI-LANA e IFI-Lítico). Os testes estatísticos de regressão logística e de razão de chances foram usados para detectar as associações estatisticamente significantes entre as PCRs positivas e as variáveis estudadas nos grupos SK/aids e HIV/aids. Os subtipos do HHV-8 foram também determinados pela técnica de PCR-RFLP da ORF K1 (VR1). Os resultados obtidos mostraram a detecção de DNA/HHV-8 em 80,2% do material de biópsia, 69,7% no sangue, 59,2% na saliva e 21,0% na urina de pacientes com SK/aids. No grupo HIV/aids, a PCR para o HHV-8 resultou positiva em 47,4% dos casos no sangue e em 26,3% na saliva e urina. Já no grupo SK clássico 100% das biópsias e salivas resultaram PCR positiva, 67% do sangue e 33% das urinas. A avaliação sorológica revelou 73,3% de reatividade para IFI-LANA e 85,3% para a IFI-Lítico no grupo SK/aids, enquanto o grupo HIV/aids mostrou reatividade de 15,8% para IFI-LANA e 47,4% para IFI-Lítico; todos os pacientes apresentaram resultados reagentes nas duas sorologias para o HHV-8 no grupo de SK clássico. No grupo controle sadio não houve reatividade na sorologia para o HHV-8, com exceção de um caso, que mostrou ser reagente na IFI-LANA. Foi possível realizar a subtipagem do HHV-8 em amostras de 69 pacientes, sendo detectadas 27 cepas do subtipo A, 13 do subtipo B, 28 do subtipo C e 1 do subtipo E. Após as análises estatísticas foi verificado que as PCRs que identificam as regiões ORF 26, ORF K8.1 e ORF 73 foram as que apresentaram melhor desempenho na identificação de DNA/HHV-8. Houve associação entre a reatividade de IFI-Lítico e a presença do vírus no sangue periférico, assim como a reatividade para IFI-LANA e a detecção de DNA/HHV-8 na saliva. Houve uma tendência dos subtipos B e C de HHV-8 serem detectados em pacientes com infecção profunda ou disseminada de SK. Estes resultados sugerem que a boca pode ser um sítio de latência da infecção por HHV-8 e confirmam a atuação de sangue, saliva e urina como fluídos potencialmente infectantes. / Since the discovery of the human herpesvirus 8 (HHV-8) as the etiological agent of Kaposi’s sarcoma (KS), several studies have been conducted in order to determine routes of virus transmission, mostly in endemic and at risk populations. The main of the present study was to determine target segments of the HHV-8 genoma and consequently infected bodily fluids. DNA sequences of ORF K1, ORF 25, ORF 26, ORF K8.1 and ORF 73 strategically localized in viral genoma were searched using nested PCR techniques in KS lesions (positive control), blood, saliva, and urine from 76 KS/aids patients, 19 HIV/aids patients, 4 classic KS patients, and among 11 healthy individuals (HIV-1 seronegative, without KS). HHV-8 subtypes were determined by PCR-RFLP of the ORF K1 (VR1), and HHV-8 antibodies by IFA-LANA and IFA-Lytic assays. The results obtained were analyzed according to epidemiological, clinical and laboratorial data, and the c2 test, logistic regression and odds ratio were applied to identify statistical association among variables in KS/aids and HIV/aids groups. The results obtained showed HHV-8 DNA in 80.2% of biopsies, 69.7% of blood, 59.2% of saliva, and 21% of urines from KS/aids group. Among HIV/aids patients, 47.4% resulted PCR positive in blood, 26.3% in saliva and urine. In classic KS cases, all biopsies and saliva resulted PCR positive, 67% in blood, and 33% in urine. The serology in KS/aids group showed 73.3% frequency of anti-latent antibodies, and 85.3% frequency of anti-lytic antibodies, while in HIV/aids group the frequencies were 15.8% and 47.4%, respectively. All classic KS cases resulted HHV-8 seroposite, while all individuals from control group resulted HHV-8 seronegative. Molecular characterization of 69 HHV-8 strains disclosed: 27 of subtype A, 13 of subtype B, 28 of subtype C, and 1 of subtype E. The ORF 26, ORF K8.1 and ORF 73 were the best segments for identifying HHV-8 DNA in bodily fluids. It was observed an association between antibodies to lytic antigens and the presence of HHV-8 in blood, and antibodies to latent antigens and the detection of HHV8 DNA in saliva of KS/aids patients. Indeed, HHV-8 subtypes B and C were detected mostly in disseminated KS cases. Taken together, the results obtained suggest that the mouth could be one site of HHV-8 latency, and confirm that blood, saliva and urine were potentially infectious bodily fluids.

O presente trabalho teve como objetivo otimizar ensaios sorológicos para serem utilizados na pesquisa de anticorpos dirigidos ao Herpesvírus humano tipo 8 (HHV-8) e com eles explorar grupos de risco para adquirir, transmitir e desenvolver doença relacionada à esta infecção, como o sarcoma de Kaposi (SK). Tomando como base a literatura disponível, as condições do laboratório e a experiência profissional acumulada na Seção de Imunologia do Instituto Adolfo Lutz de São Paulo, foram selecionados e utilizados os ensaios de imunofluorescência indireta (IFI) e Western blot (WB) para a pesquisa de anticorpos dirigidos a antígenos (Ag) de fase latente (LANA) e lítica da infecção por HHV-8. Para a padronização dos testes sorológicos foram utilizadas amostras de soro de 44 pacientes com SK e 21 controles sadios do Laboratório, e para o cálculo de prevalência de infecção HHV-8 em diferentes populações de São Paulo, soros de 3 grupos de indivíduos: - 477 pacientes infectados pelo HIV/AIDS sem SK; - 683 pacientes institucionalizados com deficiência mental e/ou física; - 736 profissionais da área da saúde, sadios. Foram empregados na preparação das lâminas de IFI e nas tiras de WB respectivamente, as células BCBL-1 latentemente infectadas pelo HHV-8 ou estimuladas com forbol éster e o antígeno viral bruto obtido de sobrenadante de lisado das mesmas células. Os resultados obtidos na padronização da IFI-LANA mostraram baixa especificidade do ensaio devendo ser acompanhado pelo teste confirmatório de WB-LANA. Por outro lado, a IFI-Lítico se mostrou altamente sensível e específica, prescindindo do teste confirmatório de WB-Lítico. Este último, devido à complexidade de componentes antigênicos aliado aos diferentes perfis de reatividade de anticorpos encontrados em soros controle positivo e negativo, não se mostrou útil para ser empregado no presente trabalho. Levando em consideração os resultados obtidos na IFI-LANA confirmados pelo WB-LANA e na IFI-Lítico, foi possível determinar a prevalência de infecção HHV-8 no grupo de pacientes infectados pelo HIV/AIDS sem SK que foi de 19,3%, sendo detectados 4,8% de soros positivos para Ag LANA e 17% para Ag Lítico. Neste grupo de pacientes, houve associação estatisticamente significante entre sorologia HHV-8 positiva, sexo masculino e prática homossexual. Baixas prevalências de anticorpos foram detectadas nos pacientes institucionalizados com deficiência mental e/ou física (1,6%) e nos profissionais da área da saúde (1,1%). Anticorpos dirigidos a Ag LANA foram encontrados em 0,6% e 0,95% dos casos, e para Ag Líticos em 1,0% e 0,3% dos casos, respectivamente. Os resultados obtidos mostram que São Paulo não é região endêmica desta infecção viral e que pacientes institucionalizados e profissionais da área da saúde não são grupos de alto risco para adquirir e transmitir o HHV-8; nenhum caso de SK foi relatado neste grupo de indivíduos na ocasião da coleta das amostras de soro. Quanto ao grupo de pacientes infectados pelo HIV/AIDS sem SK, embora 19,3% deles tenham resultado sorologia HHV-8 positiva sendo a maioria para Ag de fase lítica de replicação viral, apenas 2% desenvolveram SK em estudo longitudinal de 5 anos. A explicação encontrada para o baixo número de casos de SK nesta população de indivíduos foi a introdução em 1994, de terapia anti-retroviral em São Paulo, que mudou o curso da infecção HIV e das doenças à ela associadas. Enfim, foi possível implantar ensaios sorológicos de pesquisa de anticorpos específicos, que juntos, apresentam alta sensibilidade e especificidade e que podem ser empregados em levantamentos epidemiológicos e no diagnóstico de infecção HHV-8. / The objective of the present study was to optimize serologic assays to be employed in the search for antibodies against human herpesvirus type 8 (HHV-8) and use them to survey groups at risk to acquire, transmit and develop disease related to this infection, such as Kaposi’s sarcoma (KS). On the basis of the available literature and of the Laboratory conditions and professional experience accumulated in the Immunology Section of the Adolfo Lutz Institute of São Paulo, we selected and used indirect immunofluorescence assay (IFA) and Western blot (WB) for the search of antibodies against antigens (Ag) of the latent (LANA) and lytic phase of HHV-8 infection. Serum samples from 44 patients with KS and from 21 healthy controls from the laboratory were used for the standardization of the serologic tests, and sera from the following 3 groups of individuals were used to calculate the prevalence of HHV-8 infection in different São Paulo populations:- 477 patients infected with HIV/AIDS without KS; - 683 institutionalized patients with mental and/or physical deficiency; - 736 healthy professionals from the health area. For the preparation of IFA slides and WB strips, we respectively used BCBL-1 cells latently infected with HHV-8 or stimulated with phorbol ester and the crude antigen obtained from the supernatant of a lysate of the same cells. The results obtained in the standardization of the IFA-LANA showed low specificity of the assay, which needed to be accompanied by the confirmatory WB-LANA test. In contrast, the IFA-Lytic proved to be highly sensitive and specific, requiring no confirmatory WB-Lytic test. The latter, due to the complexity of the antigenic components joined to the different reactive profiles of the antibodies detected in positive and negative control sera, was not found to be useful for the present study. Considering the results obtained by IFA-LANA confirmed by WB-LANA and those obtained by IFA-Lytic, it was possible to determine the prevalence of HHV-8 infection in the group of HIV-AIDS patients without KS, which was 19.3%, with the detection of 4.8% sera positive for LANA Ag and 17% positive for Lytic Ag. In this group of patients there was a statistically significant association between HHV-8-positive serology, male sex and homosexual practice. Low antibody prevalences were detected in institutionalized patients with mental and/or physical deficiency (1.6%) and in health professionals (1.1%). Antibodies against LANA Ag were detected in 0.6% and 0.95% of cases, and antibodies against Lytic Ag in 1.0% and 0.3% of cases, respectively. The results obtained show that São Paulo is not an endemic region for this viral infection and that institutionalized patients and health professionals are not groups at high risk to acquire and transmit HHV-8; no case of KS was reported by these groups on the occasion of the collection of serum samples. With respect to the patients infected with HIV/AIDS without KS, although 19.3% of them showed HHV-8-positive serology, in most cases for Ag of the lytic phase of viral replication, only 2% developed KS in a 5 year longitudinal study. The small number of KS cases detected in this population is explained by the introduction in 1994 of antiretroviral therapy in São Paulo, which changed the course of HIV infection and of the diseases associated with it. In conclusion, it was possible to set up serologic assays for the detection of specific antibodies which, considered jointly, presented high sensitivity and specificity and which could be used in epidemiologic surveys and in the diagnosis of HHV-8 infection.

Human herpesvirus 6A (HHV-6A) has yet to be definitively linked to a specific disease. This is due in part to the ubiquitous nature of the virus. Humanized Rag2-/-γc-/- (Rag-hu) mice were tested to determine if these were a suitable animal model to study the virus. Both cell-free and cell-associated virus was used for infection and both were found to be efficient at infecting the mice. Viral DNA was found in the plasma and cellular blood fractions, bone marrow, lymph node, and thymus, indicating successful infection and propagation of the virus in vivo. The CD3+CD4- population was depleted, while the CD3-CD4+ was increased in infected animals. The CD3-CD4+CD8- and CD3+CD4+CD8- populations were depleted and the CD3+CD4+CD8+ population increased when analysis was gated upon CD4+ cells. The CD3-CD4+CD8+ population expanded and the CD3-CD4+CD8- population was reduced when analysis was gated on the CD3- population. Additional flow cytometry analysis revealed increases in CD4+CD8+ double positive cells in the peripheral blood of cell-free infected mice, which could indicate improper T cell selection and a premature departure of these cells from the thymus, possibly contributing to autoimmunity. Previous research has shown that HIV and HHV-6A may have a synergistic effect on one another and that HHV-6A may act as a cofactor in the progression to AIDS. After determining the Rag-hu mouse model was suitable for studying HHV-6A infection, a coinfection of HHV-6A and HIV-1 was performed. Coinfected mice had fewer thymocytes when compared with the HIV-1 only, mock-infected, and to a lesser extent HHV-6A only groups which could indicate increased cell death in the coinfected group as well as possible disruptions in migration of cells, either causing cells to be sequestered in the bone marrow and unable to migrate to the thymus, or causing premature egress of the cells in the thymus due in part to premature upregulation of CCR7, both of which would explain the smaller cellular populations found in the coinfected mouse thymi. Additional studies were performed to determine if a preferential targeting existed between HHV-6A and HIV-1 as these viruses are found simultaneously coinfecting the same cell. Preferential targeting was not observed by cell-associated migration assay, but increased migration of HHV-6A-infected cells was observed in a CCL21 dependent manner. These studies have provided useful information about HHV-6A and its relevance to HIV/AIDS as well as a possible mechanism of the involvement of HHV-6A in multiple sclerosis (MS) and other autoimmune diseases.

Le Virus Humain Herpès 8 (HHV-8) est un Herpèsvirus lymphotrope proche du virus d’Epstein Barr (EBV). Au cours de la lymphoprolifération B qu’est la Maladie de Castleman Multicentrique (MCM) HHV-8 est spécifiquement associé à une profifération de plasmablastes monotypiques IgM/. Ces cellules expriment des facteurs de transcription qui suggèrent que ces cellules sont au stade plasmablastique ou pré-plasmocytaire de la différenciation B.Les cellules invariantes Natural Killer (iNKT) sont des cellules innées qui jouent un rôle dans l’immunité antivirale, en particulier dans le contrôle des Herpèsvirus. Une diminution de ces cellules est associée à l’infection VIH ou l’âge, deux situations associées aux pathologies tumorales associées à HHV-8. Dans la première partie du travail nous avons analysés les iNKT chez des patients MCM et montrés des anomalies de fréquence et de prolifération de ces cellules. Les anomalies des cellules sont associées à des anomalies de répartition des sous populations B mémoires dans le sang circulants et la rate de ces patients. Des expériences de co-cultures montrent que les cellules iNKT pourraient être nécessaires au maintien de ces populations BDans la seconde partie de ce travail, nous avons démontré que la MCM HHV-8 est associée pendant les poussées de a maladie à une circulation dans le sang périphérique de cellules présentant les caractéristiques typiques des plasmablastes décrits jusqu’à présent uniquement dans les tissus lymphoïdes. Nous avons ensuite analysé le profil d’expression génique des cellules B infectées par HHV-8 par rapport à celui de sous populations B normales. Nos résultats montrent clairement que les cellules infectées par HHV-8 présentent un profil d’expression génique très différent de celui des sous populations B normales. Leur profil est par ailleurs caractéristique de plasmablastes. De plus, ces cellules sont en prolifération, modulent négativement l’expression de beaucoup de gènes associés à l’immunité et l’adhésion cellulaire. Enfin, nous confirmons que les cellules B infectées par HHV-8 de la MCM sont bien polyclonales même dans le sang circulant et sans mutations somatiques.Au total, ces résultats nous permettent de proposer un modèle de la physiopathologie de la MCM associée à l’infection HHV-8. / Human Herpesvirus-8 is a B-lymphotropic \γ-herpesvirus closely related to the Epstein-Barr virus (EBV). He is specifically associated with monotypic (IgM/λ) plasmablasts in Multicentric Castleman disease (HHV-8 MCD), which is a B lymphoproliferative disorder. These cells express transcription factors suggesting they are at the plasmablast or pre-pasma cell stage of differentiation. Invariant natural killer T (iNKT) cells are innate-like T cells that play a role in antiviral immunity, specifically in controlling viral replication in EBV-infected B cells. Decline of iNKT cells is associated with age or HIV infection, both situations associated with HHV-8-related diseases. We demonstrated that iNKT cell abnormalities are associated with HHV-8 MCD. These iNKT cell alterations were found to be associated with an imbalance in the frequency of circulating and splenic B cell subsets, and results of Coculturing experiments indicate that iNKT cells may be required for maintaining this cell population. In the second part of our work thesis, we demonstrate that HHV-8 MCD is associated with a unique population of circulating plasmablasts detected during the flare of the disease, with the typical phenotype of the MCD HHV-8-infected plasmablasts in MCD lesions. Then, we used gene expression profile analysis (about 48 000 genes) to further define the phenotype of this MCD HHV-8-infected cells and to investigate the lymphoma relationship to normal B cell subpopulations. The results showed that MCD HHV-8-infected cells displayed a common gene expression profile that is clearly distinct from all the normal B cell subpopulations. The gene expression profile of MCD HHV-8-infected cells was defined as plasmablastic. Moreover, the transcriptomic pattern of MCD HHV-8-infected cells demonstrates that these cells are proliferating and escaping the immune system. Finally, we determined the clonality and the cellular origin of the monotypic circulating plasmablasts by studying the rearranged immunoglobulin heavy genes in LANA+ HHV-8-infected B cells from patients with HHV-8 MCD. Our results show that these cells are polyclonal without somatic mutation. Altogether our results allowed us to elaborate a model of MCD physiopathology.