The herpes simplex virus type 1 transactivator ICPO mediates aberrant intracellular localization of the viral helicase/primase complex subunits

The infected cell polypeptide O (ICPO) protein of herpes simplex virus type 1 (HSV-1) is a promiscuous transactivator. When expressed by transfection, ICPO forms spherical structures in the nucleus. Using a double-label immunofluorescence assay, we have found that the HSV-1 helicase/primase complex subunits accumulate within ICPO structures in cotransfected cells. This phenomenon was also observed in cells coexpressing ICPO and UL6, a protein thought to be involved in the cleavage and/or packaging of viral genomes. ICPO structures were found to be proteinaceous by immunoelectron microscopy. These results suggest that ICPO may interact nonspecifically with a variety of viral proteins. (C) 1996 Academic Press, Inc.