RESUMO
Human herpesvirus 6 (HHV-6) is a ubiquitous virus that has been associated with a wide spectrum of diseases, such as exanthem infantum, multiple sclerosis, seizures, encephalitis/meningitis, and more recently, mesial temporal lobe sclerosis. Although HHV-6 is known to predominately infect CD4+ T lymphocytes, its ability to infect neural glial cells has been demonstrated both in vitro and in vivo. Reactivation of latent HHV-6 infection in the brain has recently been suggested to play a role in the development of neuropathogenesis. To investigate the association of viral gene expression and disease pathogenesis, we developed a multi-virus array containing all open reading frames of the HHV-6 virus and other pathogenically related viruses (EBV, HBV, HHV-8, HIV-1, HTLV-1, HTLV-2) to study expression of viral gene transcripts. In this study, we infected CD4+ T lymphocytes and primary human astrocytes derived from brain biopsy material in vitro with the more neurotropic HHV-6A strain. Hierarchal cluster analysis based on gene expression over time suggested a temporally regulated herpesvirus transcription process. Furthermore, we compared viral gene expression in CD4+ T lymphocytes and primary human astrocytes at peak viral load levels (>10(8) copies of virus/10(6) cells) at 5 days post-infection. Differential expression of HHV-6A genes was observed between CD4+ T lymphocytes and primary human astrocytes. Absence of a number of HHV-6 genes detected at 5 days post-infection in primary human astrocytes suggests an alternative replication strategy used by HHV-6 to evade immune detection and allow establishment of persistent infection in neural glial cells.
Assuntos
Astrócitos/virologia , Linfócitos T CD4-Positivos/virologia , Regulação Viral da Expressão Gênica/genética , Herpesvirus Humano 6/genética , Infecções por Roseolovirus/genética , Astrócitos/imunologia , Astrócitos/metabolismo , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/metabolismo , Linhagem Celular , Células Cultivadas , Criança , DNA Viral/análise , DNA Viral/genética , Encefalite Viral/genética , Encefalite Viral/imunologia , Encefalite Viral/metabolismo , Perfilação da Expressão Gênica/métodos , Herpesvirus Humano 6/imunologia , Herpesvirus Humano 6/metabolismo , Humanos , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Infecções por Roseolovirus/imunologia , Infecções por Roseolovirus/metabolismo , Ativação Transcricional/genética , Carga Viral , Replicação Viral/genéticaRESUMO
BACKGROUND: HHV-6 has been implicated in a number of neurological disorders. Recent evidence has suggested high incidence of HHV-6 infection in patients (46%) undergoing allogeneic bone marrow transplant (BMT). OBJECTIVE: To investigate whether HHV-6 plays a role in the development of fatal encephalopathy in an allogeneic post-BMT patient using an unbiased approach. RESULTS: Detection of HHV-6 viral DNA sequence and RNA expression were demonstrated in fresh frozen post-mortem autopsy material derived from the insular cortex using a multi-virus array platform. In addition, PCR analysis by real-time quantitative TaqMan demonstrated high viral burden in multiple brain regions tested. Sequencing analysis of PCR product confirmed the virus to be HHV-6 variant B. CONCLUSIONS: Active infection as demonstrated by expression of viral RNA and high viral load in the CNS suggest a possible pathogenic role of HHV-6 in development neurologic complications post-BMT.
