Bookshelf

Comparison between genomic structure and positioning of EBV and KSHV. (a) EBV: one OriP which contains two functionally different elements that are bound by EBNA 1. The DS element contains four EBNA 1 binding sites, two sites serve as minimal replicator. To ensure long-term maintenance the FR confer EBNA 1-dependent chromatin tethering. (b) KSHV: many putative origins located within TR. Two LANA binding sites resemble DS -like element and together with RE compromise the minimal replicator. The array of TRs may provide tethering function analogous to FR.

The wild-type herpes simplex virus type 1 genome consists of two major adjacent segments (the Unique long and Unique short segments), each flanked by inverted repeats. The γ₁34.5 genes are located in the inverted repeats flanking the UL segment. 1b. The R3616 HSV-1 mutant possesses a 1 kilo-basepair deletion in both copies of the γ₁34.5 gene.1c. hrR3 contains a lacZ insertion in the UL39 locus, inactivating the ICP6 (ribonucleotide reductase) gene product.1d. G207 was constructed to possess both the lacZ insertion inactivating the UL39 locus and deletions in both genes γ₁34.5.1e. HSV1716 is similar to R3616 in that too contains deletions in both copies of the γ₁34.5 gene, inactivating the ICP34.5 protein.(62)

Complete genome map of SVV. The unique long segment (UL) of the genome is flanked by 64-bp of inverted repeats (TRL and IRL). The left end of the SVV genome contains 665 bp segment that contains 506 bp of unique sequence flanked on either side by 79 bp inverted repeats; part of this inverted repeat sequence (64 bp) is present at the junction of the long and short segments (IRL) of the virus genome. The unique short segment (US) is flanked by 7557-bp of inverted repeats (IRS and TRS). Arrows indicate the direction and location of the 73 SVV ORFS corresponding to the nomenclature conventions of VZV. Black boxes indicate the repeated sequences (R1, R2, R3, and R4). The putative origins of DNA replication (ori_s) are shown. (Reprinted with permission of Virology.)

Layout of genes in mammalian herpesvirus genomes. Repeat regions are shown in thicker format than unique regions. Protein-coding regions are shown as arrows shaded grey (core genes) or white (non-core genes), and introns as narrow white bars. Blocks of core genes that are rearranged between the subfamilies are indicated by rectangles Ⅰ–Ⅶ for HSV-1, HCMV and EBV, with inverted blocks marked with a prime (Chee et al., 1990). Block Ⅱ also contains a local inversion and transposition of one gene (encoding DNA polymerase) that is not indicated. Genome coordinates and gene locations were obtained from accessions X04370 (VZV), X14112 (HSV-1), X83413 (HHV-6) as modified by Megaw et al. (1998), AY446894 (HCMV), U93872 (HHV-8) as extended at the right end of the unique region by Glenn et al. (1999), and AJ507799 (EBV). Variable numbers of terminal repeats are present in HHV-8 and EBV, but are shown at one end or the other other according to the accessions.