Pathophysiology
Clinical meaning
Cytomegalovirus (CMV) is a double-stranded DNA virus belonging to the Herpesviridae family, specifically the Betaherpesvirinae subfamily. It is one of the most common viral infections worldwide, with seroprevalence rates ranging from 40 to 100 percent depending on geographic region, socioeconomic status, and age. CMV shares a critical biological property with all herpesviruses: after primary infection, the virus establishes lifelong latency within host cells, primarily monocytes, macrophages, and CD34+ hematopoietic progenitor cells in the bone marrow. The virus can reactivate at any time, particularly during periods of immunosuppression. During primary infection, CMV enters host cells through receptor-mediated endocytosis, utilizing glycoprotein complexes on its viral envelope to bind to cellular receptors including platelet-derived growth factor receptor alpha (PDGFR-alpha) and epidermal growth factor receptor (EGFR). Once inside the cell, the viral DNA is transported to the nucleus where it hijacks the host cell's transcriptional machinery to replicate. CMV has evolved sophisticated immune evasion strategies: it downregulates major histocompatibility complex (MHC) class I and class II molecules on infected cells, interferes with natural killer cell recognition, produces viral cytokines that modulate the host immune...