Characterization of the guinea pig cytomegalovirus genome by molecular cloning and physical mapping

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Abstract
Fragments of guinea pig cytomegalovirus (GPCMV) DNA produced by HindIII and EcoRI restriction endonuclease digestion were cloned into vectors pBR322 and pACYC184; recombinant fragments representing .apprx. 97% of the genome were constructed. Hybridization of 32P-labeled cloned and gel-purified HindIII, EcoRI and XbaI fragments to Southern blots of HindIII-, EcoRI- and XbaI-cleaved GPCMV DNA verified the viral origin of cloned fragments and allowed construction of HinDII, EcoRI and XbaI restriction maps. On the basis of the cloning and mapping experiments, the size of GPCMV DNA was calculated to include 239 kilobase pairs, corresponding to a MW of 158 .times. 106. No cross-hybridization between any internal fragments was seen. Evidently, the GPCMV genome consists of a long unique sequence with terminal repeat sequences but without internal repeat regions. GPCMV DNA molecules exist in 2 forms. In the predominant form, the molecules demonstrate sequence homology between the terminal fragments; in the minor population, 1 terminal fragment is smaller by 0.7 .times. 106 daltons and is not homologous with the fragment at the other end of the physical map. The structural organization of GPCMV DNA is unique for a herpesvirus DNA, similar in its simplicity to the structure reported for murine cytomegalovirus DNA and dissimilar from that of human cytomegalovirus DNA.