The conserved UL24 family of human alpha, beta and gamma herpesviruses induces cell cycle arrest and inactivation of the cyclinB/cdc2 complex.

The conserved murine gammaherpesvirus 68 ORF20 has recently been demonstrated to induce G2 cell cycle arrest followed by apoptosis in human and mouse cells. Here, we demonstrate that its homologues UL24 in HSV-1, ORF20 in KSHV and UL76 in HCMV are also inducers of cell cycle arrest followed by apoptosis in both human and mouse cells. The mechanism of action is similar to that reported for MHV-68 ORF20, inactivating the mitotic complex cyclinB/Cdc2.