FUSION OF RECONSTITUTED INFLUENZA-VIRUS ENVELOPES WITH LIPOSOMES MEDIATED BY STREPTAVIDIN BIOTIN INTERACTIONS/

Reconstituted influenza virus envelopes (virosomes) containing the vir al hemagglutinin (HA) represent an efficient fusogenic cellular delive ry system, By interaction of HA with its natural receptors, sialylated lipids (gangliosides) or proteins, virosomes bind to cells and, follo wing endocytic uptake, deliver their contents to the cytosol through f usion from within acidic endosomes, Here, we show that binding to sial ic acid is not necessary for fusion, In the presence of streptavidin, virosomes containing a biotinylated lipid fused with liposomes lacking sialic acid if these liposomes also had a biotinylated lipid in their membranes. Moreover, fusion characteristics corresponded well with fu sion of virosomes with ganglioside-containing liposomes.