PREPROENKEPHALIN PROMOTER YIELDS REGION-SPECIFIC AND LONG-TERM EXPRESSION IN ADULT BRAIN AFTER DIRECT IN-VIVO GENE-TRANSFER VIA A DEFECTIVEHERPES-SIMPLEX VIRAL VECTOR

We have previously used a defective herpes simplex virus vector to exp ress a foreign gene in the adult rat brain. One application of this te chnology would be the in vivo analysis of promoter function in brain a fter de novo transfer, which would allow the rapid generation of vecto rs with localized application in a broad range of mammalian species wh ile avoiding influences of other nearby promoters. A 2.7-kb fragment o f the rat preproenkephalin promoter was placed upstream of the bacteri al lacZ gene in our herpes simplex virus amplicon. A restricted patter n of lacZ expression was observed in vivo, which follows previously ob served patterns of endogenous preproenkephalin expression. These resul ts, from the direct gene transfer into an adult animal brain for in vi vo promoter analysis, demonstrate that sequence information that influ ences restricted expression of preproenkephalin is located within 2.7 kb upstream of transcriptional initiation. lacZ expression was also ob served in rat brain for 2 months after direct transfer, and PCR analys is confirmed the continued presence of amplicon DNA in lacZ-positive s ections. Restricted and long-term expression observed with an endogeno us promoter has important implications for gene therapy using viral ve ctors.