The ESCRT Machinery Is Recruited by the Viral BFRF1 Protein to the Nucleus-Associated Membrane for the Maturation of Epstein-Barr Virus

TLDR

ESCRT machinery mediates membrane scission and viral budding in many RNA viruses. BFRF1 associates with ESCRT proteins, reorganizes the nuclear membrane, and induces perinuclear vesicle formation. Dominant‑negative ESCRT proteins block EBV release, retain BFRF1 at the nuclear envelope, and prevent perinuclear vesicle formation, causing viral DNA and capsid accumulation in the nucleus; BFRF1 recruits ESCRT components to remodel the nuclear envelope for EBV egress.

Abstract

The cellular endosomal sorting complex required for transport (ESCRT) machinery participates in membrane scission and cytoplasmic budding of many RNA viruses. Here, we found that expression of dominant negative ESCRT proteins caused a blockade of Epstein-Barr virus (EBV) release and retention of viral BFRF1 at the nuclear envelope. The ESCRT adaptor protein Alix was redistributed and partially colocalized with BFRF1 at the nuclear rim of virus replicating cells. Following transient transfection, BFRF1 associated with ESCRT proteins, reorganized the nuclear membrane and induced perinuclear vesicle formation. Multiple domains within BFRF1 mediated vesicle formation and Alix recruitment, whereas both Bro and PRR domains of Alix interacted with BFRF1. Inhibition of ESCRT machinery abolished BFRF1-induced vesicle formation, leading to the accumulation of viral DNA and capsid proteins in the nucleus of EBV-replicating cells. Overall, data here suggest that BFRF1 recruits the ESCRT components to modulate nuclear envelope for the nuclear egress of EBV.