Recombination of genomic terminus of bovine herpesvirus type 1 with cellular DNA

Bovine herpesvirus 1 (BHV-1) has a linear DNA genome of about 135 kb which appears as two isomers, resulting from its short unique segment being present in the two possible orientations with respect to the large unique segment. BHV-1 also circularizes its DNA to form replicative molecules. Definition of the target sequences at the genomic termini involved in the recombination events during genomic replication and isomerization, as well as virus maturation, led to the discovery that 10% of the genome molecules have additional DNA sequences attached to the right-hand terminus, as shown by electron microscopy. Three such tails have been cloned molecularly; they differ in length and nucleotide sequence, and hybridization experiments demonstrate the cellular origin of two of the three tails. The evidence presented here is consistent with a proportion of the BHV-1 genomes recombining their DNA with cellular DNA during lytic infection.