The Epstein-Barr virus immediate-early protein BZLF1 induces both a G(2) and a mitotic block.

The Epstein-Barr virus immediate-early protein BZLF1 is a transcriptional activator that mediates the switch from latent to lytic infection. Here we demonstrate that BZLF1 induces both a G(2) block and a mitotic block in HeLa cells and inhibits chromosome condensation. While the G(2) block is associated with decreased cyclin B1 in host cells and can be rescued by overexpression of cyclin B1, the mechanism for the mitotic defect is as yet undetermined.