Entry route of HCMV into endothelial cells.

Human cytomegalovirus (HCMV) is generally assumed to enter its target cells by direct fusion at the plasma membrane while sequestration and lysis of viral particles within endocytic vesicles has been suggested as an abortive entry pathway of fibroblast-adapted HCMV strains in endothelial cells. However, the finding that virions of a highly endotheliotropic strain are also found within endocytic vesicles at 10min after penetration together with the fact that the majority of these particles is translocated towards the nucleus indicates that endocytosis can be an effective entry route for HCMV in endothelial cells. HCMV-containing vesicles resemble endocytic vesicles reported for other herpesviruses with regard to size and structure suggesting a similar entry route for various herpesviruses in endocytically active cells.