ISOLATION AND CHARACTERIZATION OF 2 HERPES-SIMPLEX VIRUS TYPE-1 VARIANTS CONTAINING DUPLICATION OF SEQUENCES WITHIN THE UNIQUE LONG COMPONENT OF THEIR GENOMES

This paper reports the first spontaneous isolation of two DNA duplicat ion variants in the unique long (U-I) component of herpes simplex viru s type 1 (HSV-1) strain 17(+) genome, one (1719) with a duplication of 7.5 kb DNA sequences centered around Ori(L) and the other (1740In) wi th a 356 bp DNA duplication between the UL19 (MCP) and UL20 open readi ng frames (ORFs). The variant 1719 is stable with the rare isolation o f a wild type (strain 17(+)) genome presumably generated by the excisi on of the duplicated sequences during homologous recombination. Becaus e of the 7.5 kb duplication, UL29 (DBP) is diploid and UL30 (DNA pol) is present as one complete and one partial copy. Although duplication in the variant 1740In involved sequences from the UL20 ORF,the virus p roduces an intact UL20 gene product. Both variants show normal growth characteristics when compared with the parental viruses. DNA duplicati ons in these variants suggest a link between replication and recombina tion in HSV-1.