Gene transfer mediated by fusion protein hemagglutinin reconstituted in cationic lipid vesicles

Hemagglutinin, the membrane fusion protein of influenza virus,is known to m ediate a low-pH-dependent fusion reaction between the viral envelope and th e limiting membrane of the endosomal cell compartment following cellular up take of the virus particles by receptor-mediated endocytosis. Here we explo ited this activity of hemagglutinin to achieve efficient gene delivery to c ultured cells. Hemagglutinin was reconstituted in the presence of the monoc ationic lipid dioleoyldimethylammonium chloride (DODAC) to permit plasmid b inding to the virosome surface. Virosomes with 30 mol% DODAC exhibited a di stinct binding capacity plasmid without causing aggregation. The virosome a n activity was not affected by the cationic lipid DODAC demonstrated by low -phr-dependent lipid mixing with erythrocyte ghosts. Efficient cell transfe ction of BHK-21 cells was observed with virosomes containing 30 mol% DODAC and plasmid encoding for p-galactosidase (pCMV; beta-gal) associated to the ir surface. The transfection activity observed was dependent on the functio nal activity of hemagglutinin. Contrary to DNA/cationic lipid complexes the transfection was not dependent on the cationic lipid to DNA charge ratio. Importantly, transfection of BHK-21 cells with pCMV beta-gal by DODAC-conta ining virosomes did not show any significant signs of cytotoxicity that is commonly observed with DNA/cationic lipid complexes. Together with the high levels of expression of the transgene this highlights the potential of DOD AC-containing virosomes as a novel approach in nonviral gene transfer.