pUL25 immunolocalization in human cytomegalovirus-infected and gene-transfected cells

By means of confocal and electron microscope immunocytochemistry we have st udied the localization of a recently described structural protein (pUL25) o f human cytomegalovirus, in both infected cells and in cells transiently tr ansfected with UL25. pUL25 localization in infected cells was observed in t ypical cytoplasmic structures characterized by a very electrondense texture previously reported to accumulate other tegument proteins. At the virion l evel pUL25 seems to localize at the interface between the tegument and the capsid of both intracytoplasmic and extracellular virions. In UL-25-transfe cted cells, pUL25 has been found in characteristic para-crystalline cytopla smic aggregates, suggesting its intrinsic ability to aggregate in a regular subunit pattern.