Characterization of membrane-bound and membrane anchor-less forms of hemagglutinin glycoprotein of Rinderpest virus expressed by baculovirus recombinants.

The Rinderpest virus (RPV) hemagglutinin (H) is a class 2 glycoprotein by means of which the virus attaches to the host cell receptor. A full length cDNA coding for H protein was used to construct a recombinant baculovirus expressing the H protein, recH(M), on the surface of insect cells. The small N terminal cytoplasmic domain was deleted and the transmembrane domain which extends from amino acids 35 to 59 was replaced with a signal peptide derived from the ecdysteroid UDP glycosyl transferase (egt) gene of the baculovirus, AcNPV. The protein recH(sec) expressed by the recombinant baculovirus carrying this engineered gene was secreted into the medium. Both forms of recombinant H protein retained reactivity with conformation-dependent monoclonal antibodies. The recH(M) was recognized by antibodies made in cattle either as the result of vaccination or natural infection. The soluble form of H is a valuable tool for studying the structure and function of the RPV H glycoprotein.