Human herpesvirus 6 infection arrests cord blood mononuclear cells in G(2) phase of the cell cycle.

We here report that after infection with human herpesvirus 6A, human cord blood mononuclear cells accumulate in G(2)/M phase of the cell cycle. Experiments with foscarnet or ultraviolet (UV)-irradiated virus stocks pointed at an (immediate-)early, newly formed viral protein to be responsible for the arrest. At the molecular level, p53, cyclin B(1), cyclin A and tyrosine(15)-phosphorylated cdk1 accumulated after HHV-6A infection, indicating an arrest in G(2). However, no change was observed in the levels of downstream effectors of p53 in establishing a G(2) arrest, i.e. p21 and 14-3-3sigma. We thus conclude that the HHV-6A-induced G(2) arrest occurs independently of p53 accumulation.