To develop successful gene therapy strategies for chronic neurological diseases, a vector must be capable of long term gene expression in desired cell types. Use of a herpes simplex virus (HSV)-based vectors to deliver genes to neuronal cells is appealing because of the natural tropism for neurons; however, the expression of the transgene is less than six months. This project focuses on the role of vector chromatin structure in cessation of HSV amplicon mediated transgene expression. The hypothesis is that silencing of transcriptional activity from an HSV amplicon vector is a result of chromatin reorganization, more specifically, heterochromatinization. Thus, the primary goal of the proposed project is to determine if transcriptional silencing of the HSV amplicon genome in the striatum is a result of higher order chromatin formation. Many proteins are essential for the formation of higher order chromatin structure, and their modification can alter the level of transcriptional activity. Thus, a second goal of this project is to identify and characterize chromosomal proteins associated with amplicon DNA as well as modifications to these proteins. An understanding of the mechanism of transgene silencing in the striatum is essential in the development of strategies for obtaining long term expression of a therapeutic gene(s).
