Epstein–Barr virus nuclear antigen 1 (EBNA1) (EBNA1)

Epstein–Barr virus nuclear antigen 1 (EBNA1) is a multifunctional dimeric viral protein essential for the persistence and replication of the Epstein–Barr virus (EBV) genome in host cells [1, 2]. It functions as a sequence-specific DNA-binding protein and transcription factor, mediating the replication, maintenance, and mitotic segregation of the viral episome by tethering it to host chromosomes [2, 8, 12]. EBNA1 is uniquely expressed in all EBV-associated malignancies, including nasopharyngeal carcinoma, Burkitt's lymphoma, and Hodgkin's lymphoma, where it contributes to oncogenesis by regulating both viral and cellular gene expression and promoting cell survival [4, 16, 29]. Additionally, EBNA1 plays a role in immune evasion through its glycine-alanine repeat (GAr) domain, which inhibits its own proteasomal degradation and subsequent MHC class I presentation [2, 5, 25]. Beyond cancer, EBNA1 is implicated in the pathogenesis of autoimmune diseases like multiple sclerosis [3, 6, 15]. As a therapeutic target, EBNA1 is highly specific because it lacks a human homolog [4, 17, 30]. Small-molecule inhibitors like VK-2019 are being developed to block its DNA-binding activity and disrupt the viral lifecycle [17, 23, 27]. Other approaches include inhibiting dimerization or using PROTACs to trigger protein degradation [4, 26, 29]. Clinical trials are currently evaluating these inhibitors for efficacy in EBV-positive cancers [17, 19, 21]. Although no drugs are yet approved, EBNA1 remains a primary focus for targeted anti-EBV therapy [1, 3, 31].

Other names

EBV-NA1EBV nuclear antigen 1EBV-encoded nuclear antigen 1Human herpesvirus 4 nuclear antigen 1

EBNA1 inhibitors primarily function by blocking the protein's DNA-binding domain, preventing its interaction with the viral origin of replication (oriP), which disrupts viral genome maintenance and replication [3, 17, 23]. Other mechanisms include inhibiting EBNA1 dimerization, suppressing its expression through Hsp90 inhibition, or disrupting its interaction with host proteins like USP7 to restore p53-mediated apoptosis [4, 7, 29].