title: Spray-Dried Influenza Antigen with Trehalose and Leucine Produces an Aerosolizable Powder Vaccine Formulation that Induces Strong Systemic and Mucosal Immunity after Pulmonary Administration.
abstract: BACKGROUND
  Pulmonary immunization has recently gained increased interest as a means to induce both systemic and mucosal immunity while eliminating issues associated with the use of needles in parenteral vaccination. However, in contrast to the inhaled delivery of small molecule drugs, a dry powder carrier platform that is readily adaptable to the incorporation of biomacromolecules (e.g., vaccine antigens) as a common standard is lacking. Spray-dried trehalose with leucine has previously been characterized and demonstrated to produce highly aerosolizable powders containing an amorphous glassy matrix suitable for stabilization of biomacromolecules. This study aimed to further extend the understanding in the use of this formulation as a dry powder carrier platform in an in vivo setting, using influenza antigen as a model, for pulmonary delivery of biomacromolecules.
  
  
  METHODS
  Spray-dried influenza vaccine was produced using previously established spray-drying conditions. The formulations were characterized to examine the impact of influenza antigen on the solid-state properties of the spray-dried powders. The optimal vaccine formulation was then selected for in vivo immunogenicity study in rats to evaluate the efficacy of the reconstituted spray-dried vaccine compared to liquid vaccine administered via pulmonary and subcutaneous routes.
  
  
  RESULTS
  The formation of amorphous glassy matrix and morphology of the spray-dried particles, within the protein concentration range used in the study, was not affected by the incorporation of the influenza antigen. However, the amount of proteins incorporated increased water content and reduced the glass transition temperature (Tg) of the formulation. Nevertheless, the spray-dried vaccine induced strong mucosal and systemic immunity comparable to liquid vaccine after pulmonary and subcutaneous immunization without causing any inflammation to the lung parenchyma.
  
  
  CONCLUSIONS
  The study demonstrated the usability of the spray-dried carrier as a promising platform for pulmonary delivery of influenza vaccine. The potential utility of this delivery system for other biomacromolecules may also be further explored.
authors.affiliation: 1 Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria, Australia .
authors.forename: Tomás
authors.initials: T
authors.lastname: Sou
authors.affiliation: 1 Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria, Australia .
authors.forename: David A V
authors.initials: DA
authors.lastname: Morton
authors.affiliation: 2 Gribbles Veterinary Pathology , Clayton, Victoria, Australia .
authors.forename: Mark
authors.initials: M
authors.lastname: Williamson
authors.affiliation: 3 Department of Microbiology and ARC Centre of Excellence in Structural and Functional Microbial Genomics, Monash University , Clayton, Victoria, Australia .
authors.forename: Els N
authors.initials: EN
authors.lastname: Meeusen
authors.affiliation: 1 Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria, Australia .
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Kaminskas
authors.affiliation: 1 Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria, Australia .
authors.forename: Michelle P
authors.initials: MP
authors.lastname: McIntosh
mesh_terms: D000336:Aerosols; D000818:Animals; D000956:Antigens, Viral / Q000008:administration & dosage*; D005260:Female; D018928:Immunity, Mucosal; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000276:immunology*; D007930:Leucine / Q000008:administration & dosage*; D008168:Lung / Q000378:metabolism* / Q000473:pathology; D010316:Particle Size; D011208:Powders; D051381:Rats; D017207:Rats, Sprague-Dawley; D014199:Trehalose / Q000008:administration & dosage*; D014961:X-Ray Diffraction
chemical_list: D000336:Aerosols; D000956:Antigens, Viral; D007252:Influenza Vaccines; D011208:Powders; D014199:Trehalose; D007930:Leucine
keywords: influenza vaccine; mucosal vaccine; pulmonary delivery; spray-drying; trehalose