Infected cell protein 4 (HSV-2) (ICP4)

Infected cell protein 4 (ICP4) is a large (approximately 175 kDa) immediate early (alpha) protein encoded by the alpha 4 (UL54) gene of HSV-2. ICP4 is indispensable for viral replication; it binds to specific DNA promoter regions within the HSV genome and functions as the principal transcriptional regulator, essential for activating early (beta) and late (gamma) viral gene expression. ICP4 acts bidirectionally, promoting or repressing transcription depending on promoter and context. It is also extensively post-translationally modified and may possess GTP-binding activities. ICP4 is structurally and functionally conserved between HSV-1 and HSV-2, and is required for efficient lytic replication and for the virus to escape host cell antiviral responses. ICP4 has not been the direct target of any approved antiviral drug, but its central role makes it an ideal candidate for novel anti-herpesvirus therapeutic strategies.

Other names

ICP4Immediate early protein ICP4Alpha 4 proteinInfected cell polypeptide 4

Inhibition of viral transcription factor activity to block viral gene transcription and replication; Disruption of ICP4 binding to viral DNA promoters