Mucoadhesive liposomes for intranasal immunization with an avian influenza virus vaccine in chickens.

The aim of this study was to characterize a nasally delivered bioadhesive liposome using an inactivated H5N3 virus as a model antigen. Bioadhesive liposomes were developed using tremella (T) or xanthan gum (XG) as the bioadhesive polysaccharide. Using chickens as the target animal, we evaluated whether delivery of a bioadhesive liposomal influenza vaccine via a mucosal site of infection could improve vaccine effectiveness. 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) cytotoxicity assays demonstrated that T, XG and liposomes were non toxic to chicken spleen macrophages. Enzyme-linked immunosorbent assay (ELISA) was used to determine the adjuvant effect of the bioadhesive liposomal-vaccines. Chickens immunized with a low dose (200 microL) of bioadhesive liposomal influenza vaccine had significantly higher mucosal and serum antibody levels (P<0.05). In addition, liposomes mixed with a low-viscosity bioadhesive gel used for nasal delivery resulted in superior antibody responses compared with liposomes mixed with a high-viscosity gel (P<0.05). This suggest that a low-viscosity gel mixed with liposomes is more suitable for nasal delivery, and that chickens elicit higher mucosal secretory immunoglobulin A (s-IgA) and serum IgG after two vaccinations.