Molecular genetics of herpes simplex virus. VIII. further characterization of a temperature-sensitive mutant defective in release of viral DNA and in other stages of the viral reproductive cycle

Abstract

Previous studies have shown that cells infected with the herpes simplex virus 1(HFEM) mutant tsB7 and maintained at the nonpermissive temperature fail to accumulate viral polypeptides. Analyses of intertypic recombinants generated by marker rescue of tsB7 with herpes simplex virus 2 DNA fragments localized the mutation between 0.46 and 0.52 map units on the viral genome. The mutation in tsB7 affects several aspects of the reproductive cycle of the virus at the nonpermissive temperature. Thus, viral capsids accumulate at the nuclear pores and do not release viral DNA for at least 6 h postinfection at 39.degree. C. The DNA was released within 30 min after a shift to the permissive temperature. Experiments involving shifts from the permissive to the nonpermissive temperature indicated that viral protein synthesis was not sustained in cells maintained at the permissive temperature for < 4 h. Viral DNA synthesis was delayed at the permissive temperature for as long as 8 h. Once initiated, it continued at 39.degree. C. Marker rescue of tsB7 by transfection with herpes simplex virus 1(F) DNA fragments localized the mutation to between 0.501 and 0.503 map units on the viral genome. These results are consistent with the tsB7 lesion being in a gene coding for a virion component which affects release of viral DNA from capsids and onset of viral DNA synthesis. [African green monkey kidney Vero cells were used in this study.].