Biodegradable microparticles of influenza viral vaccine: Comparison of the effects of routes of administration on the in vivo immune response in mice

The objective of this study was to investigate the comparative immune response following administration of biodegradable microparticles loaded with influenza viral vaccine using subcutaneous and oral routes. Influenza viral vaccine was entrapped in poly(d,l-lactide-co-glycolide) (PLG) and poly(isobutylcyanoacrylate) (PIBCA) microparticles. Stability and immunogenicity of entrapped antigen were retained, as evaluated by SDS-PAGE and immunoblot. Microparticles in the size range of <11 μm were evaluated for protein loading and in vitro antigen release. The mice were immunized with microparticle loaded antigen and IgG levels in blood and IgA levels in saliva and gastric secretions were monitored by ELISA method. When the mice were immunized with microparticle suspensions, IgG levels were higher if administered by subcutaneous primed by oral route compared to oral primed by subcutaneous route or subcutaneous or oral route. The IgA level in saliva and gastric secretions were also found to be higher when subcutaneous immunization was given followed by oral booster than oral priming followed by subcutaneous booster. The polymer types of the microparticles had effects on both IgG and IgA levels. This study provided insights into the design of microparticles of influenza vaccine for subcutaneous administration followed by an unlimited oral boosting, which will have high cost-effectiveness and patient compliance. Copyright (C) 1999 Elsevier Science B.V.