Characterization of Herpes Simplex Virus 1 UL51 Self-Interaction

Following reactivation from latency herpesviruses utilize the conserved ability of cell-to-cell spread to evade the host immune response, mediating disease and viral shedding. The UL51 protein of herpes simplex virus 1 is a conserved tegument protein that functions in cytoplasmic assembly and secondary envelopment. Partial deletions of UL51 are associated with strong cell-to-cell spread defects. UL51 has no known enzymatic ability suggesting its function in cell-to-cell spread is likely dependent on specific interactions with other proteins. It has been shown to form complexes with UL7, the gE/gI complex and itself. However, it is unknown whether the self-interaction is a direct interaction or an interaction mediated by another component. A co-immunoprecipitation assay using plasmid expression of differentially tagged UL51 proteins demonstrates that the UL51 protein does not require other viral proteins for self-interaction. Using UL51 truncations coinciding with regions of conservation we began mapping regions important for self-interaction through co-immunoprecipitation and co-localization assays. We expect that determining the mechanism of interaction that UL51 has with itself will lead to the development of ways to determine the significance of the self-interactions for cell-to-cell spread, viral assembly or both.