FORMATION OF HERPES-SIMPLEX VIRUS TYPE-1 REPLICATION COMPARTMENTS BY TRANSFECTION - REQUIREMENTS AND LOCALIZATION TO NUCLEAR DOMAIN-10

During infection, the seven essential herpes simples virus type 1 (HSV -1) replication proteins are found in globular nuclear structures call ed replication compartments. Replication compartments form adjacent to ND10, nuclear matrix-bound domains which are present in most cell typ es but whose function is unknown (G. G. Maul, I. M. Ishov, and R. D. E verett, Virology 217:67-75, 1996). We now demonstrate that replication compartments can be formed by cotransfecting Vero cells with construc ts expressing the seven essential viral replication proteins and a pla smid containing an HSV-1 origin of DNA replication. Like replication c ompartments in infected cells, replication compartments formed by cotr ansfection contain all of the essential viral replication proteins, ar e sites of DNA synthesis, and are found adjacent to ND10. However, nei ther the viral origin-binding protein nor a plasmid containing an HSV- 1 origin of DNA replication is individually required for the formation of transfection replication compartments, although the presence of ea ch increases the efficiency of replication compartment formation. Furt her, we provide evidence that UL29 independently localizes adjacent to ND10 and so may play a role in directing replication compartments to these preexisting nuclear structures.