The human polyomavirus, JCV, causes a demyelinating disease in immune compromised individuals, progressive multifocal leukoencephalopathy (PML). PML is a substantial neurological complication in AIDS patients, occuring in 8% of all cases. PML is the AIDS defining illness in almost 1% of AIDS cases. Although in the past PML was a rare disease, it now represents a large number of neurological disease and is considered on the increase by recent statistics from the CDC. JC Virus was orignially thought to be strictly neurotropic, infecting only macroglial cells derived from the human brain. However, our results have now shown that there is a firm link between lymphoid and glial cells in the pathogenesis of JCV infection leading to demyelination in the human brain. We have identified the nucleotide sequences from the viral regulatory region which are signature sequences in tonsil tissues, B lymphocytes in the tonsils, and stromal cells which make up the architecture of lymphoid organs. The data indicate that the same viral genotype which is found in brain tissue of PML patients originates from an initial lymphoid cell infection. This is the first evidence for a common route for JCV infection and establishes lymphoid cells as probable carriers of virus to other tissues. The molecular similarities between these cells for JCV gene expression and cells of the nervous system directly correlated with the expression of the NF-1 class D family of DNA binding proteins which function for transcription. We have cloned the gene for NF-1/D from human brain which is highly expressed. We have prepared polyclonal antibodies to each of the 4 classes of NF-1 and used these antibodies in gel shift experiments to identify class D proteins from both brain and lymphoid tissues. There appears to be a close association between susceptibility of infection to JCV and expression of this DNA binding protein. We have made expression vectors for NF-1/D and produced cell lines which constituitively express NF-1/D. These cell lines are normally non- permissive for JCV transcription. However, we have converted them from non-permissive to permissive once selected for NF-1/D expression. We have also cloned and expressed the viral virion protein, VP1, which is responsible for cell attachment and entry of the viral particle. We have developed the methodology to allow the VP1 molecules to self- assemble into icosahedron particles like a true virion particle. We add DNA of any origin into the self assembly process and can deliver genes to any cell type. Using this system, we have been able to definitively document that susceptibility to JCV infection in humans is directly related to transcriptional regulation by cells which express high levels of NF-1/D and not to attachment and entry of the viral particle. We are now investigating individual tissue samples from AIDS patients with PML and those without to determine NF-1/D expression levels and correlation with risk of developing PML. - JC Virus, lymphoid cell infection, demyelination PML, AIDS, transcription control, NF-1/D
Showing the most recent 10 out of 41 publications
