E2F1 suppresses Epstein-Barr virus lytic reactivation through cellular and viral transcriptional networks.

Epstein-Barr virus (EBV) establishes life-long persistence infection displaying a biphasic viral life cycle - latent phase and lytic replication. While latent EBV infection is linked to several B- and epithelial cell malignancies, periodic lytic-cycle reactivation is crucial for maintaining viral progeny and transmission. Targeting lytic reactivation offers a promising therapeutic avenue for EBV-associated cancers. Our genome-wide transcriptomic analysis reveals that E2F1 is transcriptionally activated during EBV latency but significantly suppressed during lytic reactivation. While ectopic E2F1 expression suppresses lytic replication, E2F1 depletion markedly accelerates this process. Mechanistically, we establish that E2F1 and the lytic transactivator BZLF1 form a negative transcriptional feedback loop, tightly controlling viral lytic replication. Furthermore, E2F1 positively regulates c-Myc expression and together they repress leaky BZLF1 expression during latency. Notably, c-Myc does not influence E2F1 expression, nor does BZLF1 modulate c-Myc transcription, underlining a distinct regulatory hierarchy. In sum, our findings reveal that EBV tightly controls the latent-to-lytic switch through precise regulation of E2F1 expression, positioning E2F1 as a pivotal regulator of both cellular and viral gene expression.