In this study, the potential of
N-trimethyl chitosan (TMC) nanoparticles as a carrier system for the nasal delivery of a monovalent
influenza subunit vaccine was investigated. The
antigen-loaded nanoparticles were prepared by mixing a
solution containing TMC and monovalent
influenza A subunit H3N2 with a
tripolyphosphate (TPP)
solution, at ambient temperature and pH 7.4 while stirring. The nanoparticles had an average size of about 800 nm with a narrow size distribution and a positive surface charge. The nanoparticles showed a loading efficiency of 78% and a loading capacity of 13% (w/w). It was shown that more than 75% of the
protein remained associated with the TMC nanoparticles upon incubation of the particles in PBS for 3h. The molecular weight and antigenicity of the entrapped
hemagglutinin was maintained as shown by
polyacrylamide gel electrophoresis and Western blotting, respectively. Single i.n. or i.m. immunization with
antigen-loaded TMC nanoparticles resulted in strong hemagglutination inhibition and total
IgG responses. These responses were significantly higher than those achieved after i.m. administration of the subunit
antigen, whereas the
IgG1/
IgG2a profile did not change substantially. The i.n. administered
antigen-TMC nanoparticles induced higher immune responses compared to the other i.n.
antigen formulations, and these responses were enhanced by i.n. booster vaccinations. Moreover, among the tested formulations only i.n. administered
antigen-containing TMC nanoparticles induced significant
IgA levels in nasal washes of all mice. In conclusion, these findings demonstrate that TMC nanoparticles are a potent new delivery system for i.n. administered
influenza antigens.