Physical mapping of paar mutations of herpes simplex virus type 1 and type 2 by intertypic marker rescue

Abstract

Mutations (paar) in herpes simplex virus (HSV) which confer resistance to phosphonoacetic acid involve genes associated with virus-induced DNA polymerase activity. Two mutants of HSV (HSV-1 tsH and HSV-2 ts6) produce a thermolabile DNA polymerase activity. In this study, the ts lesions present in these mutants and those present in 2 independent phosphonoacetic acid-resistant mutants of HSV-1 and HSV-2 (paa4-1 and paar-2) were physically mapped by restriction endonuclease analysis of recombinants produced between HSV-1 and HSV-2 by intertypic marker rescue. All 4 mutations mapped within a 3.3-kilobase pair region around map unit 40. The accuracy of the method is reflected by the mapping results for tsH and paar-2, which lie in the same 1.3-kilobase pair region. paar-1 lies to the right ts6. Virus-induced DNA polymerase is thought to have a MW of 150,000, necessitating a gene with a coding capacity of 4.6 kilobase pairs. The 4 mutations mapped in this study all lie within a region smaller than this, but the results do not yet prove that all 4 lesions reside in this or any single gene.