Materials and Methods

Isolation and identification of CMV CMV was iso-lated in human embryonic lung fibroblast (HEL) cells as previously described [6]. For conclusive documentation that the viruses passaged in tissue culture were human CMV, DNA was purified and hybridized to specific cloned Eco RI subgenomic fragments of the AD169 strain of human CMV (provided by Dr. Deborah H. Spector), as previously described [7-9]. Nucleic acid hybridization using hu-man CMV clones was used for viral identification rather than standard immunofluorescence because of its specificity for human CMV. This technique eliminates the possibility of non-CMV antigens cross-reacting with CMV-labeled antibody potentially present in patients with AIDS. Briefly, CMV isolates were passaged in HEL cells until tv 5 x 107 cells showed 100% CPE. Cells were removed with trypsin-EDTA, pelleted and treated with RNase, SDS, and pronase. The DNA was extracted twice with phe-