Infected cell protein 4 (Herpes simplex virus type 2) (ICP4)

ICP4 is the principal immediate-early regulatory protein of herpes simplex virus type 2, essential for switching on both early and late viral gene transcription following entry into host cells. ICP4 binds to specific DNA elements in the viral genome, recruiting host and viral transcription machinery to ensure productive lytic infection. By doing so, ICP4 orchestrates the complex temporal cascade of gene expression required for viral replication and assembly. It does not encode a structural protein but acts as a master transcriptional regulator; disruption of ICP4 function blocks viral reproduction and inhibits production of infectious virus particles[6]. ICP4 is not a host protein, but a viral protein with no direct homologues in humans.

Other names

ICP4alpha gene trans-inducing factor (α-TIF)RS1 protein

Drugs or inhibitors targeting ICP4 would block or interfere with the protein’s ability to initiate and regulate transcription of essential viral genes, preventing viral replication.