Life cycle of HCMV in a human cell. Life cycle of HCMV in a human cell. HCMV enters human cells either through direct fusion or through the endocytic pathway. The virus attaches to the cell via interactions between viral glycoproteins (e.g., gB and gH) and a specific surface receptor(s) (e.g., platelet-derived growth factor α), followed by the fusion of the envelope with the cellular membrane to release nucleocapsids into the cytoplasm. These nucleocapsids are translocated into the nucleus, where viral DNA is released. This initiates the expression of IE-1/IE-2 genes. Viral replication and maturation follow the stimulation and parallel accumulation of viral synthesis function. This process involves the encapsulation of replicated viral DNA as capsids, which are then transported from the nucleus to the cytoplasm. Secondary envelopment occurs in the cytoplasm at the endoplasmic reticulum (ER)-Golgi intermediate compartment. This is followed by a complex two-stage final envelopment and egress process that leads to virion release by exocytosis at the plasma membrane. Tania Crough, and Rajiv Khanna Clin. Microbiol. Rev. 2009; doi:10.1128/CMR.00034-08