Cell-dilution PCR across a time course of infection of myeloid progenitor cells or HFs. Lysates of myeloid progenitor cells or HFs harvested on days 1, 2, 3, 5, and 11 after infection were diluted, and were analyzed by PCR with primers IEP3C and IEP4BII. The position of the 387-bp product derived from HCMV genomic DNA is indicated by arrows. Samples from either mock-infected myeloid progenitor cell cultures or HFs (Mock), productively infected HFs (Pos), or samples without any added DNA template (Neg) were included as controls. Marker was GeneRuler DNA ladder mix (Fermentas, Burlington, ON, Canada).