Recombination in Herpes Simplex Virus: Mapping of Mutations and Analysis of Intertypic Recombinants

Abstract

Herpes simplex virus types 1 and 2 (HSV-1 and HSV-2) contain linear double-stranded DNA genomes with molecular weights of about 100 × 106 (Becker et al. 1968; Kieff et al. 1971). Electron microscopic examination of self-annealed intact single strands demonstrated that virion DNA molecules were composed of unique long (Ul) and unique short (Us) regions, each flanked by inverted repeated sequences. The sequences flanking Ul are designated TRl (terminal repeat) and IRl (internal repeat). Those flanking Us are TRs and IRs (Sheldrick and Berthelot 1975). The HSV genome also exhibits a true terminal redundancy of about 0.5 × 106 daltons (Grafstrom et al. 1975a,b) which is commonly referred to as sequence a and is shared by the repeats flanking both Ul and Us. The remaining unshared sequences present in these repeat regions are termed sequence b and sequence c, as summarized in Figure 1. Sheldrick and Berthelot (1975) further predicted...