Lipid A adjuvanted Chylomicron Mimicking Solid Fat Nanoemulsions for Immunization Against Hepatitis B

Novel Biomimetic Reconstituted Built-in Adjuvanted Hepatitis B Vaccine for Transcutaneous Immunization

Transcutaneous immunization is the administration of a vaccine on the skin to generate efficient systemic and mucosal immune responses against an antigen. In the present study, reconstituted hepatitis B surface antigen vesicles (HBsAg-REVs) integrated with monophosphoryl lipid A were prepared by the delipidation-reconstitution method and tested as built-in adjuvanted vaccine, system for transcutaneous immunization using a combined approach of tape strippings, and enhanced antigen skin contact time. Prepared vesicles were extensively characterized for size, shape, zeta potential, and antigen protein loading efficiency. Following topical application, HBsAg-REVs skin permeation on isolated rat skin and cell uptake by bone marrow-derived dendritic cells were determined by confocal laser scanning microscopy and flow cytometry, respectively. The humoral and cellular immune responses elicited by HBsAg-REVs via transcutaneous immunization were comparable to the marketed intramuscular hepatitis B vaccine formulation with predefined immunization protocols. This study supports that delivery of reconstituted HBsAg vesicles via transcutaneous route may open a new vista for designing topical vaccines with possible immune protection against hepatitis B in future.

Chylomicron mimicking solid lipid nanoemulsions encapsulated enteric minicapsules targeted to colon for immunization against hepatitis B

The oral route is one of the most convenient routes for drug and/or vaccine delivery. Yet variable nature of gastrointestinal tract due to transient changes in pH, physiology, and flora throughout the gut together with hostile nature of peptide drugs/vaccines when given by this route results in limited success. Colon targeting is a recent area of interest for most of the research among which hard gelatin coated capsules is one such important and useful contrivance. The present study assesses the mucosal immunization with HBsAg loaded lyophilized nanoparticles delivered in the colonic region using enteric coated minicapsules. Designed minicapsules offers better compliance and oral vaccine antigen delivery to the colonic region which involving mucosal exposure thus mimicking the natural pathogen entry in the body. The present study is an extension of our reported work where nanoparticles were administered to the colon through the rectal route. Lyophilized nanoparticles were characterized for particle size, in-vitro release and antigen integrity along with cell uptake study. Particles had ~241 ± 32 nm sizes, flattened yet spherical in morphology. Enteric coated minicapsules were evaluated for size, coating thickness, and dissolution profile. In-vivo immune response assured its immunogenic potential with profound IgG (485 ± 41 mIU/ml) and IgA (885 ± 126 mIU/ml) antibody production as compared to marketed recombinant hepatitis B antigen formulation (Gene Vac-B®) which induce IgG and IgA titer; 1027 ± 62 mIU/ml and 220 ± 11 mIU/ml respectively following well established immunization protocol. Former induced significant mucosal immunity due to the involvement of Common Mucosal Immune System (CMIS). The study supports the workable novel approach for immune protection against hepatitis B.