Human Cytomegalovirus Genome: Partial Denaturation Map and Organization of Genome Sequences

Abstract

Contour-length measurements of nondenatured and partially denatured DNA from purified extracellular human cytomegalovirus indicate that more than 1 size class of viral DNA is encapsidated. Besides a size class averaging about 100 .times. 106 daltons, a much less abundant class of larger viral DNA molecules, 150 .times. 106-155 .times. 106 daltons, was extracted from purified extracellular virus. As predicted by melting-curve analysis, partial denaturation of human cytomegalovirus DNA generates denaturation maps showing distinctive (A + T)-rich and (G + C)-rich localizations. Alignment of partial denaturation maps of both 100 .times. 106 and 150 .times. 106 to 155 .times. 106 dalton molecules from maximum overlap of common A + T- and G + C-rich zones clearly shows 6 unique zones contained in a length equal to the longest class, 150 .times. 106-155 .times. 106 daltons. Various alignments of the smaller class of the molecules within the confines of the approximately 100 .times. 106 dalton-6ngth equivalent are nondistinctive. Of the 6 unique A + T- and G +C-rich zones, 5 are linked in a specific sequence and maintain the same relative orientation; these features indicate the absence of major inversions within these zones. The 6th unique zone may occur at either end of this 5-zone series, but it was never found at both ends of the same molecule. Additionally, this terminal zone appears to undergo complete inversions at least at 1 end of the alignment, and perhaps at both. Apparently, 150 .times. 106 to 155 .times. 106 dalton molecules comprise human cytomegalovirus-specific genetic information.