Infection of mouse ectoplacental cone cells with murine cytomegalovirus

In order to understand the mechanism of congenital cytomegalovirus (CMV) infection, we studied the effect of murine cytomegalovirus (MCMV) on murine ectoplacental cone (EPC) cells in vitro. Cytopathic effects (c.p.e.) were seen in many MCMV-infected EPC cell cultures 5 to 7 days after exposure to MCMV. The infected cells showed intranuclear inclusions characteristic of CMV infection when stained with May-Grunwald-Giemsa. Culture fluids collected from MCMV-infected EPC cells after 4 or more days of culture caused c.p.e. when co-cultivated with mouse embryo fibroblasts (MEF). Employment of the anti-complement immunofluorescence (ACIF) test detected MCMV-specific antigens, in situ hybridization localized MCMV DNA and electron microscopy detected the presence of the viral particles in the MCMV-infected EPC cells. Thus, exposure of EPC cells to MCMV in vitro resulted in a productive infection.