Expression of recombinant E2 and C proteins of rubella virus in insect cells.

We have constructed a recombinant baculovirus expressing the rubella virus E2 (42-45 KDa) and C (34 KDa) proteins. Sf9 cells infected with recombinant virus were able to synthesize and process the two proteins coded by a unique precursor gene. By immunoblot and immunoprecipitation analysis with polyclonal and monoclonal antibodies, a precursor polyprotein (66 KDa) and two other proteins migrating with an apparent molecular weight of 42 KDa and 36 KDa were recognized as E2 glycoprotein and C protein, respectively. The recombinant E2 protein appeared to be glycosylated since it was susceptible to tunicamycin. The results indicate that the RV polyprotein coding for E2 and C is expressed and proteolytically cleaved in insect cells. This baculovirus expression system provides a useful alternative approach for the production of rubella virus antigens and should allow the purification of large quantities of the RV proteins for further biochemical and immunological studies.