Transcription initiation sites and nucleotide sequence of a herpes simplex virus 1 gene conserved in the Epstein-Barr virus genome and reported to affect the transport of viral glycoproteins.

Earlier reports have localized mutations which affect the processing and transport of herpes simplex virus 1 glycoproteins to a region located between the genes specifying glycoprotein B and the major viral DNA-binding protein (beta 8). The nucleotide sequence of this region contains a single long open reading frame encoding a 780-amino-acid protein with a predicted molecular weight of 83,845. To confirm the existence of this protein, rabbit polyclonal antibody was made against a synthetic peptide made according to the predicted sequence of a hydrophilic domain near the carboxy terminal of the protein. This antibody reacted with an infected cell protein of an apparent molecular weight of 95,500. We designated this protein infected cell protein 18.5 (ICP18.5). S1 nuclease analysis suggested that the 5.6-kilobase mRNA encoding ICP18.5 is initiated predominantly from one site, but three weaker initiation sites also seemed to occur within a 74-base-pair stretch of DNA. This gene appears to be conserved in the Epstein-Barr virus (EBV) genome, inasmuch as 174 of the 780 amino acids of ICP18.5 align with corresponding amino acids predicted by the EBV open reading frame BALF3. The EBV gene is located adjacent to the gene specifying a homolog of the herpes simplex virus 1 glycoprotein B.