In situ localization of the major capsid protein during lytic infection by herpes simplex virus.

The intracellular localization of the major capsid protein (ICP5) of herpes simplex virus was studied during virogenesis. Except for a brief period at the onset of synthesis, this protein was found almost exclusively inside the nucleus. Its localization was not at random since 80% was tightly bound to the nuclear matrix as early as 4 h after infection. Discrete modifications of the fluorescence pattern occurred in an orderly fashion during the progression of the infection. Immunoelectron microscopic studies using Protein A-gold labelling demonstrated that this protein is synthesized on cytoskeleton-bound polyribosomes and accumulates in the central part of the nucleus where formation of viral capsids occurs; no gold particles were found in association with the peripheral chromatin or with the nucleolus.