Peer-review started: September 7, 2015
First decision: October 8, 2015
Revised: October 28, 2015
Accepted: December 4, 2015
Article in press: December 8, 2015
Published online: February 12, 2016
Herpes simplex virus 1 (HSV-1) is a ubiquitous human pathogen that establishes latent infection in ganglia neurons. Its unique life cycle requires a balanced “conquer and compromise” strategy to deal with the host anti-viral defenses. One of HSV-1 α (immediate early) gene products, infected cell protein 0 (ICP0), is a multifunctional protein that interacts with and modulates a wide range of cellular defensive pathways. These pathways may locate in different cell compartments, which then migrate or exchange factors upon stimulation, for the purpose of a concerted and effective defense. ICP0 is able to simultaneously attack multiple host pathways by either degrading key restrictive factors or modifying repressive complexes. This is a viral protein that contains an E3 ubiquitin ligase, translocates among different cell compartments and interacts with major defensive complexes. The multiple functional domains of ICP0 can work independently and at the same time coordinate with each other. Dissecting the functional domains of ICP0 and delineating the coordination of these domains will help us understand HSV-1 pathogenicity as well as host defense mechanisms. This article focuses on describing individual ICP0 domains, their biochemical properties and their implication in HSV-1 infection. By putting individual domain functions back into the picture of host anti-viral defense network, this review seeks to elaborate the complex interactions between HSV-1 and its host.
Core tip: Due to the genomic limitation, viruses often use multifunctional proteins to ensure viral replication. Coordination of the multiple viral functions is critical for a successful viral infection. Infected cell protein 0 (ICP0) is notoriously multi-functional in terms of simultaneously targeting many host machineries located in different cellular compartments. Understanding the molecular basis of ICP0 multifunctionality is important for not only the elucidation of herpes simplex virus pathogenicity but also the delineation of host defense mechanisms.