A STRUCTURAL AND FUNCTIONAL COMPARISON OF THE LATENCY-ASSOCIATED TRANSCRIPT PROMOTERS OF HERPES-SIMPLEX VIRUS TYPE-1 STRAINS KOS AND MCKRAE

The promoters of the latency-associated transcripts (LATs) of herpes s implex virus type 1 (HSV-1) strains KOS and McKrae were compared to ex amine their influence upon the reactivation phenotypes of these two st rains. Unlike strain KOS, McKrae is readily reactivatable using in viv o reactivation models. We found greater than 96% sequence conservation between KOS and McKrae in the LATs promoter region, and both promoter s showed equivalent basal and inducible activities. An inter-strain re combinant (termed MK13) was constructed in which the LATs promoter of HSV-1 McKrae was recombined into the background of HSV-1 strain KOS. I n a murine u.v. light-induced reactivation model, virus shedding was d etected by eye swabbing in two of 44 (5%) mice infected with KOS, 20 o f 42 (48%) mice infected with McKrae and none of 45 (0%) mice infected with MK13. These data show that the LATs promoters of these viruses a re structurally and functionally similar and that transfer of the LATs promoter from McKrae into KOS is insufficient to confer a reactivatab le phenotype.