Effect of Rta protein of Epstein-Barr virus on the cell cycle in HeLa cells.

Epstein-Barr virus (EBV) replication and transcription activator (Rta) is an immediate-early transcription factor that mediates the switch from latent to lytic infection. DNA viruses often modulate the function of critical cell cycle proteins to maximize the efficiency of virus replication. Here we have examined the effect of Rta on cell cycle progression. Cell cycle analysis revealed that Rta induced HeLa cells in G0/G1-phase to reenter the S-phase. Analysis of the expression pattern of a key set of cell cycle regulators revealed that expression of Rta inhibited the expression of Rb and p53 and induced the expression of E2F1. These findings suggest that Rta plays an active role in redirecting HeLa cell physiology through an Rta-mediated cell cycle transformation.