EXPRESSION AND CHARACTERIZATION OF A SOLUBLE RUBELLA-VIRUS E1 ENVELOPE PROTEIN

Individual specific antigenic rubella virus (RV) structural proteins a re required for accurate serological diagnosis of acute and congenital rubella infections as well as rubella immune status. The RV envelope glycoprotein El is the major target antigen and plays an important rol e in viral-specific immune responses. The native virion is difficult t o produce in large quantities and the protein subunits are also diffic ult to isolate without loss of antigenicity. The production of a solub le RV El (designated E1 Delta Tm) using the baculovirus-insect cell ex pression system is described. In contrast to wild-type RV El, the gene tically engineered E1 Delta Tm protein lacks a transmembrane anchor. I t behaved as a secretory protein and was secreted abundantly from inse ct cells. Pulse-chase studies were used to examine the synthesis, glyc osylation, and secretion of E1 Delta Tm by the insect cells. The secre ted E1 Delta Tm protein was purified from serum-free medium by onestep immunochromatography. The purified E1 Delta Tm protein retained full antigenicity and may be a convenient source of El protein for use in d iagnostic assay and rubella vaccine development. (C) 1994 Wiley-Liss, Inc.