Liposomal immunisation against snake venoms.

A method is described which produces a high, permanent antibody response following a single injection of venom. Animals (mice, rabbits, sheep) were given intravenous, subcutaneous or orally administered Nigerian Echis carinatus (carpet viper) venom which had been incorporated into sphingomyelin-cholesterol liposomes whose membranes had been stabilized by cross-linking adjacent molecules of sphingomyelin using osmium tetroxide. Before use the preparations were thoroughly dialysed to remove any unbound osmium tetroxide. Antibody levels were estimated using enzyme immunoassay. Venom treated in this way and administered i.v. or s.c. produced a powerful, sustained and protective antibody response lasting for the lifetime of a mouse. We also report the development of significant antibody responses after oral administration of liposome-entrapped but not free venom.