The proteoglycan form of bovine herpesvirus 1 and bovine herpesvirus 5 glycoprotein G gene products: A novel modification for herpesviral glycoproteins

The genes encoding the homologs of alphaherpesviral glycoprotein G (gG) are located within the unique short segment of the viral genome. Analysis and comparison of the aminoacid sequences deduced from the open reading frames (ORFs) encoding gG of bovine herpesvirus I (BHV-1) and bovine herpesvirus 5 (BHV-5) revealed the structure predicted for type I glycoproteins and showed that the homologs share 75 % identical and 85 % similar amino acids. Polyvalent antisera, raised in rabbits against recombinant vaccinia viruses expressing the respective ORFs precipitated secreted glycoproteins of 65 kDa from BHV-1 and BHV-1 infected cell culture media, designated gG, and a high a diffusely migrating protein species with apparent molecular mass between 90 and > 240 kDa. The last was shown to be an chondroitin sulfate containing isoform of gG and was designated glycoproteoglycan G (gpgG). For BHV-1 it was demonstrated that gG and gpgG are not essential for repliction in cell culture and in bovines. Both gG and gpgC could not be found in purified virions, indicating that they are not involved in the entry process into target cells and in the target cell tropism of BHV-1. No role of gG and gpgG could be found for replication in cell culture and also the function of these proteins in vivo awaits identification