ANALYSIS OF SEQUENCES IMPORTANT FOR HERPES-SIMPLEX VIRUS TYPE-1 LATENCY-ASSOCIATED TRANSCRIPT PROMOTER ACTIVITY DURING LYTIC INFECTION OF TISSUE-CULTURE CELLS

We describe the analysis of the herpes simplex virus type 1 (HSV-1) la tency-associated transcript (LAT) promoter using an HSV-1-based vector system. Sequences under investigation for LAT promoter activity were analysed for their ability to direct chloramphenicol acetyltransferase gene expression, either in transfection assays or following their ins ertion into an HSV-1 vector from which the endogenous LAT promoter seq uences had been removed. The analysis mapped the main determinants of LAT promoter activity during lytic infection of tissue culture cells t o a 277 bp region between -279 and -2 relative to the recognized 5' en d of the primary 8.3 kb transcript. The LAT promoter constructs behave d similarly in the context of the virus genome and in the plasmid-base d transfection assays. Comparison of the relative activities following infection of fibroblast and neuroblastoma cell lines indicates that s equences upstream from -279 are important for LAT promoter activity in neurons.