David Davido
Associate Professor
Department of Molecular Biosciences
University of Kansas


Determination of Protein-Protein Interactions of the HSV-1 ICP0 C-terminal Domain (2016-2017)

The results from this proposal examining functional interactions between viral and host factors can used to develop new therapies for preventing or treating herpetic diseases. Herpes simplex virus (HSV) infections, typically characterized by physiologically-distinct lytic and latent phases, result in intermittent mouth (cold) and genital sores and are the primary cause of infectious blindness in western industrialized countries. HSV can initiate a lytic infection, establish a latent infection in sensory neurons, or reactivate from latency by stress stimuli (e.g., heat shock).

A key player in determining whether an infection will be lytic or latent is the immediate-early (IE) protein of HSV, ICP0. ICP0 is a 110-KDa protein that initiates strong transactivation of viral gene expression.It can synergistically stimulate the expression of early (E) and late (L) viral genes with the major IE transcription factor of HSV, ICP4. Studies using ICP0 mutant viruses have shown that ICP0’s activation of viral gene expression is required for efficient lytic replication and reactivation. The C-terminus of ICP0 contains a large region that activates HSV gene expression either alone or in combination with ICP4. Notably, this C-terminal region contains ICP0’s dimerization and ICP4-interaction domains, which have been hypothesized to regulate ICP0 transactivation of HSV genes. The structures of ICP0 binding to itself and its interaction with ICP4 have been unexplored. Until the molecular mechanisms that regulate ICP0 activities are understood, it will not be possible to fully understand the roles ICP0 play in HSV life cycle.

The long-term goal of our research is to understand the interactions between viral factors, relating findings from our studies to recurrent herpetic diseases. Given the one-year time frame of this pilot project, the objective of this application is to identify ICP0’s interaction with itself and ICP4 that are associated with stimulating viral gene expression. Our central hypothesis is that specific C-terminal amino acid residues that facilitate ICP0 dimerization and/or interaction with ICP4 are required for efficient HSV gene expression. Our rationale for these studies is that, by identifying molecular events in ICP0 functions, it may be possible to develop new anti-HSV therapies.

The following aims are proposed: Aim #1 is to determine the structure of ICP0-ICP0 and ICP0-ICP4 interaction domains, and Aim #2 is to identify ICP0-ICP0 and ICP0-ICP4 contacts that stimulate HSV gene expression.