title: Encapsulation of native crotoxin in liposomes: a safe approach for the production of antivenom and vaccination against Crotalus durissus terrificus venom.
abstract: Crotoxin, the neurotoxic component of Crotalus durissus terrificus (Cdt) venom that displays phospholipase A2 activity, was successfully encapsulated into dehydration-rehydration vesicles (DRV/crotoxin) and reverse-phase evaporation vesicles (REV/crotoxin) made from sphingomyelin and cholesterol. The encapsulation efficiency of native crotoxin was higher in DRV/crotoxin than in REV/crotoxin. DRV/crotoxin was not toxic when i.v. inoculated in mice at a dose of crotoxin as high as 91 times its L.D50 or when s.c. inoculated at 42 times its LD50. On the other hand, crotoxin released from DRV/crotoxin retained its original toxicity. REV/crotoxin was found to be at least 1.9 times more toxic than DRV/crotoxin. The fact that DRV/crotoxin retained crotoxin more efficiently than REV/crotoxin may account for the difference in acute toxicity between the two preparations. DRV/crotoxin, when s.c. inoculated in mice, induced anti-crotoxin antibodies that protected animals against the lethal effect of Cdt venom. Following immunization with three doses of DRV/crotoxin (3 x 20 micrograms of crotoxin/mouse) and challenge with 8 x LD50 of Cdt venom, 75% of mice were protected. The DRV/crotoxin preparation was compared to crotoxin emulsified in Freund's adjuvant (FCA/crotoxin). DRV/crotoxin was found to be less toxic than FCA/crotoxin, and to induce lower levels of anti-crotoxin antibodies but similar levels of protection when inoculated at high doses (20 or 70 micrograms crotoxin/mouse). When DRV/crotoxin was adsorbed to alum at the time of immunization, it induced antibody and protection levels comparable to those produced by FCA/crotoxin.
authors.affiliation: Centro de Pesquisa e Desenvolvimento, Fundaçào Ezequiel Dias (FUNED), Belo Horizonte, Minas Gerais, Brazil.
authors.forename: T V
authors.initials: TV
authors.lastname: Freitas
authors.forename: F
authors.initials: F
authors.lastname: Frézard
mesh_terms: D000818:Animals; D000997:Antivenins / Q000096:biosynthesis* / Q000378:metabolism / Q000633:toxicity; D003439:Crotoxin / Q000276:immunology* / Q000378:metabolism / Q000633:toxicity; D004337:Drug Carriers; D004355:Drug Stability; D005260:Female; D005620:Freund's Adjuvant; D007115:Immunization Schedule; D008081:Liposomes; D051379:Mice; D008815:Mice, Inbred Strains; D016019:Survival Analysis; D014614:Vaccines, Synthetic / Q000276:immunology* / Q000378:metabolism / Q000633:toxicity
chemical_list: D000997:Antivenins; D004337:Drug Carriers; D008081:Liposomes; D014614:Vaccines, Synthetic; D003439:Crotoxin; D005620:Freund's Adjuvant