Deoxyribonucleoprotein complexes and DNA synthesis of herpes simplex virus type 1.

Two temperature-sensitive mutants of herpes simplex virus type 1 in complementation group 1-1 were analyzed to determine if the major DNA-binding protein they produced was thermolabile. Cells infected with these mutants were analyzed for deoxyribonucleoprotein complexes containing the DNA-binding protein. These complexes were found in cells infected at the permissive temperature but not at the nonpermissive temperature. In temperature shift-up experiments with mutant virus infected cells, the levels of the deoxyribonucleoprotein complexes decreased with time of incubation at the nonpermissive temperature. Viral DNA synthesis terminated in cells infected with these mutants after temperature shift-up. The kinetics of termination of viral DNA synthesis were similar to the kinetics of dissociation of the deoxyribonucleoprotein complexes. These results indicate that two mutants in complementation group 1-1 produce a thermolabile DNA-binding protein and that this protein is required for viral DNA synthesis. Furthermore, they suggest that the major DNA-binding protein of herpes simplex virus type 1 functions in viral DNA synthesis as a component of deoxyribonucleoprotein complexes.