An Adenovirus DNA Replication Factor, but Not Incoming Genome Complexes, Targets PML Nuclear Bodies.

UNLABELLED: Promyelocytic leukemia protein nuclear bodies (PML-NBs) are subnuclear domains implicated in cellular antiviral responses. Despite the antiviral activity, several nuclear replicating DNA viruses use the domains as deposition sites for the incoming viral genomes and/or as sites for viral DNA replication, suggesting that PML-NBs are functionally relevant during early viral infection to establish productive replication. Although PML-NBs and their components have also been implicated in the adenoviral life cycle, it remains unclear whether incoming adenoviral genome complexes target PML-NBs. Here we show using immunofluorescence and live-cell imaging analyses that incoming adenovirus genome complexes neither localize at nor recruit components of PML-NBs during early phases of infection. We further show that the viral DNA binding protein (DBP), an early expressed viral gene and essential DNA replication factor, independently targets PML-NBs. We show that DBP oligomerization is required to selectively recruit the PML-NB components Sp100 and USP7. Depletion experiments suggest that the absence of one PML-NB component might not affect the recruitment of other components toward DBP oligomers. Thus, our findings suggest a model in which an adenoviral DNA replication factor, but not incoming viral genome complexes, targets and modulates PML-NBs to support a conducive state for viral DNA replication and argue against a generalized concept that PML-NBs target incoming viral genomes.

IMPORTANCE: The immediate fate upon nuclear delivery of genomes of incoming DNA viruses is largely unclear. Early reports suggested that incoming genomes of herpesviruses are targeted and repressed by PML-NBs immediately upon nuclear import. Genome localization and/or viral DNA replication has also been observed at PML-NBs for other DNA viruses. Thus, it was suggested that PML-NBs may immediately sense and target nuclear viral genomes and hence serve as sites for deposition of incoming viral genomes and/or subsequent viral DNA replication. Here we performed a detailed analyses of the spatiotemporal distribution of incoming adenoviral genome complexes and found, in contrast to the expectation, that an adenoviral DNA replication factor, but not incoming genomes, targets PML-NBs. Thus, our findings may explain why adenoviral genomes could be observed at PML-NBs in earlier reports but argue against a generalized role for PML-NBs in targeting invading viral genomes.