The inverted repeat regions of the simian varicella virus and varicella-zoster virus genomes have a similar genetic organization

Simian varicella virus (SVV) causes a varicella-like disease in nonhuman primates. The DNA sequence and genetic organization of the inverted repeat region (RS) of the SVV genome was determined. The SVV RS is 7559 bp in size with 56% guanine + cytosine (G+C) content and includes 3 open reading frames (ORFs). The SVV RS1 ORF encodes a 1279 amino acid (aa) protein with 58 and 39% identity to the varicella-zoster virus (VZV) gene 62 and herpes simplex virus type 1 (HSV-1) ICP4 homologs, respectively. The predicted 261 aa SVV RS2 polypeptide possesses 52% identity with the VZV gene 63 homolog and 23% identity with the HSV-1 ICP22. The SVV RS3 encodes a 187 aa polypeptide with 56% and 28% identity to the VZV gene 64 and the HSV-1 US10 homologs, respectively, and includes an atypical zinc finger motif. A G+C-rich 16 base-pair (bp) sequence which is repeated 7 times and a putative SVV origin of replication were identified between the RS1 and RS2 ORFs. Comparison with the VZV RS indicates the SVV and VZV RS regions are similar in size and genetic organization.