title: Chitosan-based nanoparticles for improving immunization against hepatitis B infection.
abstract: The design of effective vaccine delivery vehicles is opening up new possibilities for making immunization more equitable, safe and efficient. In this work, we purpose polysaccharidic-based nanoparticles as delivery structures for virus-like particle antigens, using recombinant hepatitis B surface antigen (rHBsAg) as a model. Polysaccharidic-based nanoparticles were prepared using a very mild ionic gelation technique, by cross-linking the polysaccharide chitosan (CS) with a counter ion. The resulting nanoparticles could be easily isolated with a size in the nanometric range (160-200 nm) and positive surface charge (+6 to +10 mV). More importantly, CS-based nanoparticles allowed the efficient association of the antigen (>60%) while maintaining the antigenic epitope intact, as determined by ELISA and Western blot. The entrapped antigen was further released in vitro from the nanoparticles in a sustained manner without compromising its antigenicity. In addition, loaded CS-based nanoparticles were stable, and protected the associated antigen during storage, either as an aqueous suspension under different temperature conditions (+4 degrees C and -20 degrees C), or as a dried form after freeze-drying the nanoparticles. Finally, immunization studies showed the induction of important seroprotection rates after intramuscular administration of the nanoparticles, indicating their adjuvant capacity. In fact, CS-based nanoparticles were able to induce anti-HBsAg IgG levels up to 5500 mIU/ml, values 9-fold the conventional alum-adsorbed vaccine. In conclusion, we report here a polysaccharidic nanocarrier which exhibits a number of in vitro and in vivo features that make it a promising adjuvant for vaccine delivery of subunit antigens.
authors.affiliation: Nanobiofar Group, Department of Pharmacy and Pharmaceutical Technology, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Prego
authors.forename: Patrizia
authors.initials: P
authors.lastname: Paolicelli
authors.forename: Belen
authors.initials: B
authors.lastname: Díaz
authors.forename: Sara
authors.initials: S
authors.lastname: Vicente
authors.forename: Alejandro
authors.initials: A
authors.lastname: Sánchez
authors.forename: Africa
authors.initials: A
authors.lastname: González-Fernández
authors.forename: María José
authors.initials: MJ
authors.lastname: Alonso
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage*; D000818:Animals; D048271:Chitosan / Q000008:administration & dosage*; D003692:Delayed-Action Preparations / Q000008:administration & dosage; D004337:Drug Carriers / Q000008:administration & dosage*; D005260:Female; D006510:Hepatitis B Antibodies / Q000097:blood; D006514:Hepatitis B Surface Antigens / Q000235:genetics / Q000276:immunology; D017325:Hepatitis B Vaccines / Q000276:immunology*; D007114:Immunization / Q000379:methods*; D007074:Immunoglobulin G / Q000097:blood; D007273:Injections, Intramuscular; D051379:Mice; D008807:Mice, Inbred BALB C; D053758:Nanoparticles / Q000008:administration & dosage*; D014614:Vaccines, Synthetic / Q000235:genetics / Q000276:immunology
chemical_list: D000276:Adjuvants, Immunologic; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines; D007074:Immunoglobulin G; D014614:Vaccines, Synthetic; D048271:Chitosan