FIG. 7.

Infection of term and first trimester placental trophoblasts and HEL cells as a function of virus concentration. HEL cells and trophoblasts from term and first trimester placentas cultured with EGF were prepared in 96-well tissue culture plates as described in Materials and Methods. Cells were challenged with CMV strain AD169 at the MOI indicated on the horizontal axis, and the number of IE-positive cells was determined after 24 h. Percentages were calculated from the mean number of positive cells per microwell of four replicate wells from one of two independent experiments. Cell number per microwell was calculated as described in Materials and Methods.