Abstract
Two independently derived cell lines which carry the herpes simplex type 2 thymidine kinase gene have been examined for the presence of HSV- 2-specific DNA sequences. Both cell lines contained 1 to 3 copies per cell of a sequence lying within map co-ordinates 0.2 to 0.4 of the HSV- 2 genome. Revertant cells, which contained no detectable thymidine kinase, did not contain this DNA sequence. The failure of EcoR1- restricted HSV-2 DNA to act as a donor of the thymidine kinase gene in transformation experiments suggests that the gene lies close to the EcoR1 restriction site within this sequence at a map position of approx. 0.3. The HSV-2 kinase gene is therefore approximately co-linear with the HSV-1 gene.