BORNA-DISEASE VIRUS P24 AND P38 40 SYNTHESIZED IN A BACULOVIRUS EXPRESSION SYSTEM - VIRUS PROTEIN INTERACTIONS IN INSECT AND MAMMALIAN-CELLS/

To facilitate studies of the individual viral proteins, two Borna dise ase virus proteins, p24 and p38/40, were synthesized in vitro by means of a baculovirus expression system and examined for antigenic identit y to viral proteins from BDV-infected cells. Recombinant proteins p24 and p38/40 were nearly identical in size to the viral proteins from BD V-infected cells. Immunoblot and immunocytochemistry analysis of BDV p roteins from infected tissue culture cells and rat brain showed bindin g of antisera directed against the recombinant proteins. Specific reco gnition of the recombinant proteins by Borna disease virus-specific co nvalescent antisera and monoclonal antibodies further demonstrated tha t the antigenic characters of the p24 and p38/40 had been conserved. P olyclonal antibody directed against either of the recombinant proteins recognized only the protein used as immunogen, without cross reactivi ty with the other recombinant protein, indicating no common epitopes. Moreover, these data confirmed the proposed gene coding assignments of ORF I and II of BDV p38/40 and p24, respectively. Both of the recombi nant proteins were secreted into the media of insect cells in tissue c ulture, but secretion of recombinant p24 was evident only as a dimeric form and not with the monomeric form. Immunoprecipitation studies per formed with monoclonal antibodies and BDV proteins from infected rat b rain suggested that a heterodimer forms via binding of p40 to the p24. (C) 1994 Academic Press, Inc.