A PROTOTYPE RECOMBINANT VACCINE AGAINST RESPIRATORY SYNCYTIAL VIRUS AND PARAINFLUENZA VIRUS TYPE-3

We have produced a genetically-engineered chimeric protein composed of the external domains of the respiratory syncytial virus (RSV) fusion (F) protein and the parainfluenza virus type 3 (PIV-3) hemagglutinin-n euraminidase (HN) protein in insect cells using the baculovirus expres sion system. The yield of the soluble chimeric F-RSV-HNPIV-3 protein c ould be increased approximately 2-fold by using Trichoplasia ni (High Five) insect cells in place of Spodoptera frugiperda (Sf9) for express ion. The chimeric protein, purified from the supernatant of baculoviru s-infected High Five cells by immunoaffinity chromatography was correc tly processed at the F2-F1 proteolytic cleavage site. Immunochemical a nalysis of the chimera with a panel of anti-F and anti-HN monoclonal a ntibodies suggested that the antigenicity of the major F and HN neutra lization epitopes of the chimeric protein was preserved. Immunization of cotton rats with two 1 or 10 mu g doses of the chimeric protein ads orbed to aluminum phosphate elicited strong PIV-3 specific HAI respons es as well as PIV-3 and RSV specific neutralizing antibodies, and at e ither dose completely protected against challenge with live RSV and PI V-3.