Cells that constitutively express the herpes simplex virus immediate-early protein ICP4 allow efficient activation of viral delayed-early genes in trans

To study the role of herpes simplex virus type 1 immediate-early proteins in the transcriptional activation of herpes simplex virus genes, we isolated stably transformed cells expressing herpes simplex virus type 1 ICP4, an immediate-early protein known from previous studies to be necessary for delayed-early and late transcription. These cells efficiently expressed six delayed-early herpes simplex virus genes introduced by viral superinfection, …