Characterization of a viable, noninverting herpes simplex virus 1 genome derived by insertion and deletion of sequences at the junction of components L and S.

Earlier studies have shown that the DNA of herpes simplex virus 1 consists of two covalently linked components, L and S, each flanked by inverted repeats. The two components can invert, and viral DNA extracted from infected cells or virions consists of equimolar concentrations of four populations differing solely in the orientation of L and S components relative to each other. This paper describes a recombinant virus (1358) generated by an insertion of a chimeric thymidine kinase gene within the reiterated sequences of the S component and deletions that eliminated most of the internal inverted repeats at the junction between the L and S components. A characteristic of 1358 is that the L and S components are frozen in one (prototype) orientation. Inversion of L and S components is therefore not required for the replication of viral DNA.