The linear double-stranded DNA genome of herpesvirus as it is present in infectious virions needs to be circularized after infection of host cells and before DNA replication. Replicative-form genomes have to be cleaved into linear unit-length molecules during virion maturation and are most probably the substrate for inversion of the short segment relative to the long segment of the bovine herpesvirus 1 (BHV-1) genome. Those regions of the BHV-1 genome which are functionally involved in these processes have been analyzed at the molecular level by cloning and sequencing the genomic termini, the fusion of both termini from replicative-form molecules, and the junction between the short and the long genome segment. On the basis of the simple genome arrangement of BHV-1, it was inferable that the cleavage of replicative-form genomes by a hypothetical BHV-1 terminase activity may be specified by a sequence at the left end of UL (An element), which is located proximal to a reiterated beta element that makes up the cleavage site itself. The relationship of those elements in BHV-1 and the comparison to similar regions of other herpesviruses indicate consensus sequence elements which are functionally important for cleavage and isomerization of viral DNA during maturation of virions.