Persistence of human cytomegalovirus DNA sequences without cell-virus homology in human placental explants in culture.

Using histopathology, virology, and molecular probing, we investigated the potential of human first-trimester placental tissue to support human cytomegalovirus (HCMV) infection. Histopathologic examination of infected placental explants revealed cellular changes characteristic of HCMV infection. Immunohistochemical staining of infected explants with human convalescent sera demonstrated expression of HCMV antigens within the cytotrophoblast. Dot blot hybridization of DNA extracted from infected placental tissue using cloned Hind III "W" fragment of HCMV genome indicated the presence of HCMV sequences without virus-cell homology in infected explants from one to ten days post-infection. In general, the sequences detected by the viral probes increased in abundance with time as infection continued.