Cytomegalovirus infection andpathogenesis in the human placenta

Human cytomegalovirus (HCMV) is themost common cause of congenital viral infection. Affected children can have permanent neurological complications, including hearing loss, visual impairment and mental retardation1–3. In Aus-tralia, 57%ofwomenare seronegative andat risk forprimary infection and transmission of virus to the fetus during preg-nancy4. Despite its public health significance, the specific molecular and cellular basis of HCMV replication in the human placenta and pathogenesis associated with poor clinical outcome are unknown. Direct fetal infection is in-volved in severe cases of neuropathology and infection of the placenta can impair its development and functions resulting in a hypoxic environment5–8 and stillbirth6,9,10. Gestational age at the time of infection is an important determinant of outcome. The rates of virus transmissio