Heat-shock promoter-driven synthesis of secreted bovine herpesvirus glycoproteins in transfected cells.

The bovine hsp70A heat-shock gene promoter was isolated and used to direct the heat-regulated synthesis of bovine herpesvirus glycoproteins gIII and gIV in transfected cultured bovine cells. Sequences encoding the viral glycoproteins incorporated mutations that deleted the transmembrane anchors. Both proteins were efficiently secreted from transfected cells in a temperature-dependent manner and the gIV so produced was found to be antigenically similar to the authentic molecule. Stable cell lines with regulated expression of these proteins were obtained and repeated thermal cycling of the cultures enabled high-yield production of these subunit vaccine antigens. The continuous production demonstrated by this system is highly relevant to the efficient and economic manufacture of vaccines and other protein biopharmaceuticals.