MUTATIONAL ANALYSIS OF SEQUENCES DOWNSTREAM OF THE TATA BOX OF THE HERPES-SIMPLEX VIRUS TYPE-1 MAJOR CAPSID PROTEIN (VP5 UL19) PROMOTER/

Transient expression assays with the herpes simplex virus type 1 (HSV- 1) promoter/leader controlling the betagamma (leaky-late) VP5 (U(L)19) mRNA encoding the major capsid protein showed that no more than 36 to 72 bases of VP5 leader are required for full-level expression. Constr ucts lacking the viral leader and the transcription initiation site ex pressed the reporter gene at about 20% of the maximum level. We confir med this observation by using recombinant viruses in which VP5 promote r/leader deletions controlling the bacterial beta-galactosidase gene w ere inserted into the nonessential glycoprotein C (U(L)44) locus of th e genome. Sequences within +36 are required for full-level expression, and removal of all leader sequences including the cap site resulted i n a 10-fold decrease in reporter mRNA accumulation. The removal of the leader sequence had a measurable effect upon the kinetics of reporter mRNA accumulation, but insertion of the entire VP5 leader and cap sit e into a construct in which the reporter gene was controlled by the ki netically early (beta) dUTPase (U(L)50) promoter did not result in any significant change in the kinetics of dUTPase promoter expression. Th ese results suggest that DNA sequences both 5' and 3' of the TATA box are important determinants of the betagamma kinetics and levels of VP5 mRNA accumulation in the infected cell.