Cytomegalovirus replication in primary and passaged human placental cells.

Human cytomegalovirus (HCMV) was found to replicate in passaged fibroblastic human first trimester and term placental cells. The time-course of viral DNA replication as well as virus production in these human placental fibroblasts was similar to that in human embryo fibroblast cultures. In contrast, HCMV did not replicate in primary placental epithelioid cells. Continued passage (5 or more) of primary placental epithelioid cells was necessary to convert these cells to a state of permissiveness. The permissive cells were, however, fibroblasts. HCMV DNA replication in passaged placental fibroblastic cells was not affected by treatment with insulin or human chorionic gonadotropin. Furthermore, no replication of HCMV DNA occurred in choriocarcinoma cells, the epithelioid cells derived from cancer of the placenta. These results suggest that epithelial placental trophoblasts, either normal or transformed, were nonpermissive for HCMV. The permissiveness of HCMV infection to secondary placental cells which was observed might be due to the strong selection of fibroblastic cells in vitro.