Foot and Mouth Disease virus-loaded fungal chitosan nanoparticles for intranasal administration: impact of formulation on physicochemical and immunological characteristics

Nasal vaccination is a promising, needle-free alternative route for parenteral vaccination. This study introduces a simple, scalable nasal vaccine delivery formulation for Foot and Mouth Disease virus (FMDv) using chitosan (CS) nanoparticles and assesses the potential of fungal CS for use as nanocarriers for mucosal vaccines. Fungal CS was extracted from fungal biomass and physiochemically characterized. FMDv-loaded CS nanoparticles, prepared using an ionic gelation technique, were characterized for particle size, zeta potential, morphology, loading efficiency and virus particle release. The immunogenicities of nasally applied FMDv-loaded fungal or commercial shrimp CS were compared with intraperitoneally administered fluid vaccine in guinea pigs. The nanoparticles had varied sizes (221.9-281.2 nm), positive electrical charge (+7 to +13 mV) and excellent antigen-loading capacity (93-97%). In vitro release studies revealed a biphasic virus particle release for all CS nanoparticles. Higher serum titers were developed with CS formulations than with free virus and were comparable with the titers for intraperitoneally administered fluid vaccine. Significantly higher IgA levels were found after the administration of nasal vaccine than after fluid vaccine or free virus. Overall, CS-FMDv nanoparticles stimulated humoral and mucosal immunity following intranasal administration. Fungal CS polymers were potent mucosal immunoadjuvants and showed promise as alternative sources of CS for mucosal vaccine formulations.