Physical mapping of herpes simplex virus type 1 mutations by marker rescue.

A generally applicable technique which permits the rescue of selected genetic markers from fragments of herpes simplex virus DNA is described. Baby hamster kidney cells infected at the nonpermissive temperature with intact DNA from temperature-sensitive mutants or with fragmented wild-type DNA produce no, or little, infectious progeny. Coinfection results in an increased yield of virus, demonstrating the rescue of genetic information from the DNA fragments. This progeny virus consists of both wild-type and temperature-sensitive virus, demonstrating that both recombination and complementation can occur in coinfected cells. Rescue experiments using isolated fragments produced with various restriction endonucleases have enabled us to locate five temperature-sensitive mutations on the herpes simplex virus type 1 physical map. An adaptation of the technique has allowed the physical mapping of a mutation which affects the herpes simplex virus type 1 pyrimidine deoxyribonucleoside kinase gene. Comparison of the genetic and physical maps for these mutants reveals several anomalies which are discussed.