LOCALIZATION OF HUMAN CYTOMEGALOVIRUS STRUCTURAL PROTEINS TO THE NUCLEAR MATRIX OF INFECTED HUMAN FIBROBLASTS

The intranuclear assembly of herpesvirus subviral particles remains an incompletely understood process. Previous studies have described the nuclear localization of capsid and tegument proteins as well as intran uclear tegumentation of capsid-like particles. The temporally and spat ially regulated replication of viral DNA suggests that assembly may al so be regulated by compartmentalization of structural proteins. We hav e investigated the intranuclear location of several structural and non structural proteins of human cytomegalovirus (HCMV). Tegument componen ts including pp65 (ppUL83) and ppUL69 and capsid components including the major capsid protein (pUL86) and the small capsid protein (pUL48/4 9) were retained within the nuclear matrix (NM), whereas the immediate -early regulatory proteins IE-1 and IE-2 were present in the soluble n uclear fraction. The association of pp65 with the NM resisted washes w ith 1 M guanidine hydrochloride, and direct binding to the NM could be demonstrated by far-Western blotting. Furthermore, pp65 exhibited acc umulation along the nuclear periphery and in far-Western analysis boun d to proteins which comigrated with proteins of the size of nuclear la mins. A direct interaction between pp65 and lamins was demonstrated by coprecipitation of lamins in immune complexes containing pp65. Togeth er, our findings provide evidence that major virion structural protein s localized to a nuclear compartment, the NM, during permissive infect ion of human fibroblasts.