DNA sequence and transcriptional analysis of the simian varicella virus glycoprotein B gene

The varicella-zoster virus (VZV) glycoprotein B (gB) is a major viral antigen which elicits immunity and neutralizing antibodies. In this study, the genomic map position and DNA sequence of a simian varicella virus (SVV) homologue of the VZV gB gene was identified and the transcript analysed. A 32P-labelled VZV gB DNA probe hybridized to a subclone of the SVV BamHI B restriction endonuclease fragment indicating the fine map position of SVV DNA sequences homologous to the VZV gB gene. The SVV gB DNA sequence was determined and analysis revealed a 2751 base pair open reading frame (ORF) with 71.1% identity to the VZV gB gene and 53.8% identity to the herpes simplex type 1 gB gene. The SVV gB ORF encodes a 916 amino acid polypeptide with a predicted molecular mass of 104K. The deduced SVV and VZV gB polypeptides share 78.9% amino acid identity and predicted N-linked glycosylation sites, cleavage sites and transmembrane regions. 32P-labelled SVV gB DNA and RNA probes hybridized to a 3.5 kilobase SVV polyadenylated transcript. Primer extension experiments identified transcript start sites for the SVV and VZV gB genes and permitted a comparison of the sequences upstream of the SVV and VZV gB ORFs. The SVV and VZV gB promoter elements are similar in content and align closely. The VZV gB transcript start site suggests a gB polypeptide initiation site which is inconsistent with the previously reported ATG start codon.