Tandem repeated DNA in an intergenic region of herpes simplex virus type 1 (Patton)

When the entire US region of HSV-1 (Patton) was cloned as an EcoRI fragment in bacteriophage lambda gtWES, the BamHI B6B5 fragment was observed to vary in size among independent isolates [Umene and Enquist, Gene 13 (1981) 251-268]. This fragment polymorphism also occurred in DNA of HSV-1 single plaque isolates. We report here that this heterogeneity is due to variation in copy number of a 15-bp tandem repeat of sequence 5'-CCACTCCCCACCCAC-3', which apparently lies in an intergenic region of the HSV-1 DNA.