Association of ganglioside-protein conjugates into cell and Sendai virus. Requirement for the HN subunit in viral fusion.

A method is described for preparing a covalent conjugate of proteins, in particular antibodies and their fragments, with gangliosides in the micellar form. The protein-ganglioside conjugate is associated with ganglioside micelles and can be separated from free protein by molecular sieve chromatography. Conjugates can irreversibly transfer from the micelle to a cell membrane of choice, and the protein portion be identified as a new surface antigen. The successful application of this methodology has been demonstrated with three biological systems. Rabbit IgG-ganglioside conjugate has been transferred to human or sheep erythrocytes, which have been hemagglutinated with goat anti-rabbit IgG. Erythrocytes modified with ganglioside-anti-H2Kk have been shown to adhere to monolayers of L929 mouse fibroblasts which express H2Kk-antigen. Mouse monoclonal anti-glycophorin ganglioside conjugate can associate with Sendai virus and confer upon the virus the ability to agglutinate and hemolyse desialylated human erythrocytes. Using the anti-glycophorin conjugate, we demonstrated that the HN subunit, which is normally responsible for viral binding, appears also to be essential for fusion activity, because its destruction eliminates hemolysis and fusion, but not agglutination, by the conjugate-modified virus.