Herpes simplex virus immediate-early protein ICP4 (ICP4)

Herpes simplex virus immediate-early protein ICP4 is a critical regulatory protein essential for the life cycle of both HSV-1 and HSV-2. As a major transcriptional activator, it coordinates the transition from immediate-early to early and late viral gene expression by binding to specific DNA sequences and recruiting host cellular transcription factors, such as TFIID and TFIIB. Without functional ICP4, the virus cannot proceed with DNA replication or the production of infectious progeny, making it a high-value target for antiviral intervention. While current standard-of-care treatments like acyclovir target the viral DNA polymerase, ICP4 is being actively explored as a target for novel therapeutics, including gene-editing tools and small-molecule inhibitors designed to disrupt its DNA-binding or oligomerization domains. Targeting ICP4 offers a potential strategy to overcome resistance to polymerase inhibitors and may provide a pathway toward addressing latent infections.

Other names

Infected cell protein 4Vmw175IE175Regulatory protein ICP4RS1

Inhibition of viral gene expression by preventing the recruitment of the transcription initiation complex or disrupting the protein's ability to bind to viral DNA promoters.