Sequence of the Putative Origin of Replication in the UL Region of Herpes Simplex Virus Type 1 ANG DNA

Institute for Virus Research, German Cancer Research Center, 6900 Heidelberg, Federal Republic of Germany Interest has been stimulated concerning the region mapping between 0.38 and 0.42 on the prototype configuration of the herpes simplex virus type 1 (HSV-1) genome due to the high probability of the presence there of a second origin of DNA replication. A 960 bp restriction fragment ( Hin fI E) of a class II defective HSV-1 ANG DNA has been sequenced using the viral DNA rather than molecularly cloned DNA. This fragment includes the Bam HI U/R cleavage site, mapping at approximately 0.4. Part of the sequence derived in this study displays homology with the origins of DNA replication contained in TR S /IR S of HSV-1 and HSV-2 DNA. The homologous region comprising 76 bp occurs as two copies, each of which contains two palindromically arranged copies of an 8 bp sequence identical to the ‘consensus’ sequence reported to be part of the origin of DNA replication at the terminus of the mammalian adenoviruses. It can be deduced from a comparison of this structure to the TR S /IR S origin of HSV-1 and HSV-2 that there are two origins of replication in the U L region of HSV-1 ANG DNA. Assuming that the orientation of the consensus sequence is relevant to the direction of DNA replication, one can conclude that the U L origin(s) of HSV-1 ANG is (are) bidirectional. It has not yet been possible to clone DNA fragments molecularly which include the region spanning the U L origin(s) of HSV-1 DNA. Keywords: HSV-1, U L , origin of replication Present address: EMBL, Meyerhofstrasse 1, 6900 Heidelberg, F.R.G. Received 5 June 1984; accepted 29 August 1984.