ABSTRACT
Liposomes also serve as target membranes for viruses, and certain types of liposomes have been demonstrated to sustain fusion with viruses under conditions identical to those necessary for fusion with biological membranes. Lipid-enveloped viruses infect their host cells by fusing either with the plasma membrane, or the endosome membrane following endocytosis of the virions. Because of their relatively simple membrane composition, viruses have proved to be a useful experimental system to study the mechanisms of membrane fusion. Membrane fusion reactions also take place between cell membranes. Certain cytoplasmic proteins, such as synexin and clathrin, were shown to modulate or induce the fusion of liposomes. These observations have emphasized the relevance of the liposome fusion model for biological membrane fusion. The rate constants express the effect of various factors on aggregation and fusion as separate processes. In some liposome systems, the leakage of contents may be too rapid to enable the accurate determination of the rate of fusion.
