EFFECT OF SUBSTITUTION OF HEMAGGLUTININ-NEURAMINIDASE WITH INFLUENZA HEMAGGLUTININ ON SENDAI VIRUS F PROTEIN-MEDIATED MEMBRANE-FUSION

Recombinant virosomes containing fusion protein (F) of Sendai virus and the envelope glycoproteins hemagglutinin (HA) and neuraminidase (NA) of influenza virus within the same membrane were prepared. Such hybrid vesicles were found to hemolyse red blood cells both at pH 7.4 and pH 5.0. Hemolysis induced by hybrid vesicles was much higher than seen with F-virosomes in the presence of WGA, but was about two-fold less than the hemolysis caused by F,HN-virosomes, Reconstituted influenza virus envelopes and F-virosomes failed to induce hemolysis at pH 7.4. Using a fluorescence probe-based lipid mixing fusion assay, hybrid virosomes were found to fuse with cultured HeLa cells both at pH 7.4 as well as pH 5.0. The data indicate that the presence of Sendai virus HN protein in the virosomal membrane is not absolutely essential for the virosome-cell fusion process.