Physical mapping of two herpes simplex virus type 1 host shutoff loci: rescue of each ts mutation occurs with two unique cloned regions of the viral genome.

Two complementing temperature-sensitive (ts) herpes simplex virus type 1 (HSV-1) mutants, PAA1rts1 and ts199, were defective in viral DNA synthesis and in the shutoff of cellular macromolecular synthesis at 39.5 degrees C, the nonpermissive temperature. PAA1sts1 and PAA1rts1+ recombinants and PAA1rts1+ revertants were used to examine the contributions of the PAA1r mutation and the ts1 mutation of PAA1rts1 in affecting the levels of viral and cellular DNA synthesized at 34 and 39.5 degrees C. The results of this study suggests an interaction between the viral DNA polymerase and the ts1+ gene product during HSV-1 DNA replication and possibly in the inhibition of host DNA synthesis by HSV-1. Physical mapping of the ts mutations present in ts199 and the PAA1sts1 recombinant ts1-8 were performed by intratypic marker rescue experiments. Surprisingly, both the ts1-8 and ts199 mutations were rescued by two cloned fragments: ts1-8 by BglII-K (map coordinates 0.095 to 0.163) and BglII-I (map coordinates 0.314 to 0.417), while ts199 was rescued by BglII-K and BglII-O (map coordinates 0.163 to 0.197). In more refined mapping experiments, the regions between coordinates 0.347 to 0.378 and 0.126 to 0.163 were able to rescue the ts1-8 mutation. Southern hybridization analysis confirmed that the fragments that rescued ts1-8 and those that rescued ts199 had homology, as predicted by the physical mapping results.