Progressive multifocal leukoencephalopathy (PML) is a subacute neurodegenerative disease of the central nervous system caused by the human polyomavirus, JCV. PML, once a relatively rare disease of middle- aged and elderly patients with a background of immunologic impairment is now much more common due to the high prevalence of AIDS. The surprisingly higher incidence of PML in AIDS patients than in other immunosuppressive disorders has suggested that the presence of Human Immunodeficiency Virus type 1 (HIV-1) in the brain may directly and indirectly contribute to the pathogenesis of this disease. It is hypothesized that cytokines, the peptide hormones which control the homeostasis of the immune system and have a fundamental role in inflammatory and immune-mediated reactions, participate in AIDS neuropathology by facilitating cross-communication between HIV-1 and other opportunistic infectious particles including JCV. Support for this hypothesis stems from results of several laboratories indicating that infection of microglia and astrocytes with HIV-1 stimulates production of some of these cytokines such as TGFbeta, TNF, and IL-1 both in vitro and in vivo. Furthermore, our studies revealed that several cytokines, including TGFbeta and IL-1, have the capacity to augment expression of the JCV genome in glial cells.
The aim of the research outlined in this proposal is to define the molecular mechanism by which the JCV genome is transcriptionally activated by HIV-1-induced cytokines in glial cells. The experimental design includes: 1) Examination of JCV gene expression and viral DNA replication in lytically infected primary glial cultures treated with TNFalpha, IL-1, and TGFbeta; 2) Identification of the regulatory elements which participate in this induction by: (i) targeting DNA sequences within the viral promoter which are required for this induction; (ii) defining the cellular factor(s) which enhance JCV activity by interacting with the JCV genome; 3) Evaluation of the biological activities of cytokine-induced regulatory protein(s) on JCV gene transcription. The information gained from these studies should increase our understanding of the molecular mechanism involved in the development of PML and other disorders prevalent in AIDS patients, and provide critical information for devising effective and safe strategies for disease prevention.
