ANALYSIS OF FACTORS INFLUENCING KINETICS OF HERPES-SIMPLEX VIRUS TRANSCRIPTION UTILIZING RECOMBINANT VIRUS

The herpes simplex virus type 1 (HSV-1) transcription program is a reg ulated cascade in which early and late phases of gene expression are s eparated by viral DNA replication. While promoters controlling express ion of transcripts encoding immediate-early proteins contain virus-spe cific cis-acting elements, these are in the context of cellular promot er elements, and the promoters controlling expression of other viral t ranscripts contain only cellular cis-acting elements. We had developed and continue to refine a general method for the production of recombi nant viruses in which modified promoters can be inserted into nonessen tial loci within the viral genome through homologous recombination. Th is approach has been especially useful in defining the features of mod el promoters of the various kinetic classes. Our work suggests that cl ass-specific differences in promoter architecture are critical factors in the ability of the cellular transcription machinery to form stable preinitiation complexes at various phases of infection and, thus, med iate kinetic class-specific transcription. Early (beta) promoters cont ain a TATA box and upstream activation elements while sequences downst ream of the TATA homology are dispensible for transcription. Late tran scripts can be catagorized as either leaky-late (beta gamma) or strict late (gamma) depending on whether they are readily detectable prior t o viral DNA replication. Promoters controlling both types are clearly distinct from early ones in that sequences near the transcription star t site which resemble consensus mammalian initiator elements are requi red along with the TATA box and activator elements. Strict late promot ers do not contain elements upstream of the TATA box but include what appears to be a class specific element downstream of the transcription start site. (C) 1998 Academic Press.