Human origin recognition complex binds to the region of the latent origin of DNA replication of Epstein-Barr virus

Epstein-Barr virus (EBV) replicates in its latent phase once per cell cycle in proliferating B cells. The latent origin of DNA replication, oriP, supp orts replication and stable maintenance of the EBV genome. OriP comprises t wo essential elements: the dyad symmetry (DS) and the family of repeats (FR ), both containing clusters of binding sites for the transactivator EBNA1. The DS element appears to be the functional replicator. It is not yet under stood how oriP-dependent replication is integrated into the cell cycle and how EBNA1 acts at the molecular level. Using chromatin immunoprecipitation experiments, we show that the human origin recognition complex (hsORC) bind s at or near the DS element. The association of hsORC with oriP depends on the DS element. Deletion of this element not only abolishes hsORC binding b ut also reduces replication initiation at oriP to background level. Co-immu noprecipitation experiments indicate that EBNA1 is associated with hsORC in vivo. These results indicate that oriP might use the same cellular initiat ion factors that regulate chromosomal replication, and that EBNA1 may be in volved in recruiting hsORC to oriP.