title: Intranasal delivery of Norwalk virus-like particles formulated in an in situ gelling, dry powder vaccine.
abstract: The development of a vaccine to prevent norovirus infections has been focused on immunization at a mucosal surface, but has been limited by the low immunogenicity of self-assembling Norwalk virus-like particles (NV VLPs) delivered enterically or at nasal surfaces. Nasal immunization, which offers the advantage of ease of immunization, faces obstacles imposed by the normal process of mucociliary clearance, which limits residence time of applied antigens. Herein, we describe the use of a dry powder formulation (GelVac) of an inert in situ gelling polysaccharide (GelSite) extracted from Aloe vera for nasal delivery of NV VLP antigen. Powder formulations, with or without NV VLP antigen, were similar in structure in dry form or when rehydrated in simulated nasal fluids. Immunogenicity of the dry powder VLP formulation was compared to equivalent antigen/adjuvant liquid formulations in animals. For the GelVac powder, we observed superior NV-specific serum and mucosal (aerodigestive and reproductive tracts) antibody responses relative to liquid formulations. Incorporation of the TLR7 agonist gardiquimod in dry powder formulations did not enhance antibody responses, although its inclusion in liquid formulations did enhance VLP immunogenicity irrespective of the presence or absence of GelSite. We interpret these data as showing that GelSite-based dry powder formulations (1) stabilize the immunogenic structural properties of VLPs and (2) induce systemic and mucosal antibody titers which are equal or greater than those achieved by VLPs plus adjuvant in a liquid formulation. We conclude that in situ gelation of the GelVac dry powder formulation at nasal mucosal surfaces delays mucociliary clearance and thereby prolongs VLP antigen exposure to immune effector sites.
authors.affiliation: Center for Infectious Diseases and Vaccinology, The Biodesign Institute, Arizona State University, PO Box 875001, Tempe, AZ 85287-5001, USA.
authors.forename: Lissette S
authors.initials: LS
authors.lastname: Velasquez
authors.forename: Samantha
authors.initials: S
authors.lastname: Shira
authors.forename: Alice N
authors.initials: AN
authors.lastname: Berta
authors.forename: Jacquelyn
authors.initials: J
authors.lastname: Kilbourne
authors.forename: Babu M
authors.initials: BM
authors.lastname: Medi
authors.forename: Ian
authors.initials: I
authors.lastname: Tizard
authors.forename: Yawei
authors.initials: Y
authors.lastname: Ni
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Arntzen
authors.forename: Melissa M
authors.initials: MM
authors.lastname: Herbst-Kralovetz
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage; D000281:Administration, Intranasal; D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D000917:Antibody Formation; D017250:Caliciviridae Infections / Q000517:prevention & control*; D002460:Cell Line; D005260:Female; D006168:Guinea Pigs; D006801:Humans; D051379:Mice; D008854:Microscopy, Electron; D009092:Mucous Membrane / Q000276:immunology; D029322:Norovirus / Q000276:immunology*; D011134:Polysaccharides; D011208:Powders; D051381:Rats; D058425:Vaccines, Virus-Like Particle / Q000008:administration & dosage / Q000276:immunology* / Q000648:ultrastructure
chemical_list: D000276:Adjuvants, Immunologic; D000914:Antibodies, Viral; D011134:Polysaccharides; D011208:Powders; D058425:Vaccines, Virus-Like Particle