TRANSDUCTION OF FOREIGN REGULATORY SEQUENCES BY A REPLICATION-DEFECTIVE HERPES-SIMPLEX VIRUS TYPE .1. THE RAT NEURON-SPECIFIC ENOLASE PROMOTER

Herpes simplex virus type 1 (HSV-1) can transduce genes into non-proli ferating cells such as neurons that are refractory to other means of g ene transfer. We have been interested to examine the potential usefuln ess of HSV-1 as a gene transfer vehicle to analyze neuron-specific reg ulatory sequences. In this study, we have used a replication-defective HSV-1-based vector deleted for the essential immediate early gene 3 ( IE3) to transduce a 1.8 kb promoter fragment from the rat neuron-speci fic enolase gene (nse) linked to the firefly luciferase reporter gene (luc). It has previously been shown that the same promoter fragment is capable of directing neuron-specific expression of a linked reporter gene in transgenic mice. As an internal control for infection and gene expression, we also inserted the chloramphenicol acetyltransferase (c at) gene driven by the SV40 early promoter/enhancer into the thymidine kinase locus of the same vector. We infected (i) non-neuronal BHK-C13 cells which do not express the endogenous nse gene, (ii) differentiat ed and non-differentiated pheochromocytoma PC12 cells as well as (iii) N1E-115 neuroblastoma cells, all of which do express endogenous nse. All three cell types produced luciferase upon infection, indicating th at the same nse promoter fragment that has previously been shown to be regulated in a cell-specific manner in transgenic mice, was not regul ated cell type-specifically in the context of the HSV-1 genome. Theref ore, the nse promoter fragment may either be incomplete (and genomic s equences in the transgenic mice may have compensated for this deficien cy), or the function of the present control elements is affected by ad jacent HSV sequences and is thus template-dependent.