Multifaceted roles of RAP80 during the Herpes simplex virus 1 life cycle

Herpes simplex virus 1 (HSV-1) is a widespread human pathogen that establishes lifelong infections, but understanding precise activity at each infection stage remains challenging. HSV-1 utilizes ubiquitination pathways to modulate cellular factors to facilitate its replication cycle, however, elucidating the cascades that follow host protein degradation and the subsequent impact on the host-virus equilibrium continues to be a complex endeavor. Here we reveal the multifaceted role of the DNA damage response protein RAP80 throughout HSV-1's infection cycle. In early stages, RAP80 inhibits HSV-1 transcription by directly binding to the viral genome, blocking ICP4 (viral protein) binding to transcription factors. This interaction is regulated by phase separation via an intricate interplay between RAP80 and ICP0/ICP4. As infection progresses, the viral E3 ligase ICP0 degrades RAP80, dissolving phase separation, and allowing the formation of a mature viral replication compartment. In late infection stages, RAP80 is deubiquitinated by the viral deubiquitinase UL36USP, which restores cellular homeostasis and promotes HSV-1 survival. This process involves modulating the R-loop-cGAS-apoptosis pathway. These findings underscore the dynamic interplay between viral and host factors and the complex mechanisms used by HSV-1 to subvert host defenses, offering practical implications for the future development of antiviral strategies. Overall design: Chromatin immunoprecipitation DNA-sequencing (ChIP-seq) for RAP80 in HeLa cells infected by HSV-1 at 3h and 20h post-infection.