The varicella-zoster virus genome

Abstract

The varicella-zoster virus (VZV) genome contains at least 70 genes, and all but six have homologs in herpes simplex virus (HSV). Cosmids and BACs corresponding to the VZV parental Oka and vaccine Oka viruses have been used to "knockout" 34 VZV genes. Seven VZV genes (ORF4, 5, 9, 21, 29, 62, and 68) have been shown to be required for growth in vitro. Recombinant viruses expressing several markers (e.g., beta-galactosidase, green fluorescence protein, luciferase) and several foreign viral genes (from herpes simplex, Epstein-Barr virus, hepatitis B, mumps, HIV, and simian immunodeficiency virus) have been constructed. Further studies of the VZV genome, using recombinant viruses, may facilitate the development of safer and more effective VZV vaccines. Furthermore, VZV might be useful as a vaccine vector to immunize against both VZV and other viruses.

Figure 1

Comparison of the VZV and HSV genomes. The VZV genome (first rows) contains unique long (UL) and unique short (US) regions flanked by terminal long (TRL), terminal short (TRS), internal long (IRL), and internal short (IRS) repeats. VZV genes (second rows) and HSV genes (third rows) are shown by numbers. VZV or HSV genes that do not have homologs in the corresponding virus circled. The HSV genome contains UL and US regions, and TRL, TRS, IRL, and IRS repeats (fourth rows). Modified from Cohen 1999, with permission.