CMV genome conformation in PB CD14⁺ cells. For all panels the top (Origin) of the gel is represented on the right and the bottom of the gel is depicted on the left. Symbols + and − indicate positive and negative controls for PCR. Numbers 8, 5, and 4 label the probe-positive cores for panels (B), (C), and (D), respectively. Size markers (315 bp and 202 bp) for the primary and nested PCR products, respectively, are represented. (A) Ethidium bromide–stained gel showing a representative lane containing 10⁸ cells of S flexneri bacteria carrying the ≈230-kb circular megaplasmid marker. Ethidium bromide staining of bacterial chromosomal DNA is associated with the region near the well origin (Origin). The lower edge of the proteinase K/SDS/agarose trough is seen as a brightly stained region midway between the circular marker and the well origin. The circular megaplasmid control migrated at core 8 for all gels shown in panels (B), (C), (D), and (E). The apparent linear megaplasmid band (Linear) invariably comigrated with the CMV linear band as exemplified in the positive cores after PCR amplification of low copy CMV-infected cells (E). (B) DNA blot analysis of nested PCR products, from an inclusive series of sequential agarose cores collected from the gel lane prepared from set 1 of pooled CD14⁺ cells from five donors. (C) DNA blot analysis similar to (B), from set 2 (3 donors). (D) DNA blot analysis of primary PCR products, from set 3 (5 donors) and using only 10% of the proteinase K normally used in block preparation. (E) Ethidium bromide–stained gel of PCR amplification of low copy CMV-infected cells.