Encapsulation of Inactivated Newcastle Disease Virus Onto the Chitosan Nanoparticles for Use in Mucosal Immunity

Newcastle disease virus (NDV) as the causative agent of a serious respiratory infection threatens the poultry industry worldwide. The risk of an outbreak of NDV could be restricted by mass vaccination. Here we brought up methodology to generate chitosan (CS)-based NDV nanoparticles as an antigen carrier for delivery into intranasal mucosa.

The NDV antigen was produced in the allantoic cavity of 9-11-day embryonated SPF chicken eggs. The virus was tittered and inactivated by ethylene imine. The CS nanoparticles were prepared by ionic gelation method. The physicochemical properties including size, distribution, charge, and morphology of the particles were evaluated. The CS-based NDV nanoparticles were prepared by encapsulation of the inactivated NDV antigen and validated based on the factors affecting optimal encapsulation. The toxicity and safety of the nanoparticles were assayed using inoculation of HLM cells as well as by administration of SPF chickens.

The CS nanoparticles were produced with an average size of 196 nm and good morphology. After encapsulation of NDV antigen, the mean diameter of the nanoparticles was 328  nm with an encapsulation efficiency of ~83% and loading capacity of ~54%. The electron microscopy study indicated that the particles had a spherical shape. The in vitro cytotoxicity and the in vivo safety of the CS-based NDV nanoparticles results indicated the particles were not toxic either in LMH cells or in chickens.

By considering factors that represent optimal nanoparticles, the safe inactivated NDV nanoparticles were successfully developed. This study lays the foundation for the further development of mucosal vaccines and drugs encapsulated in chitosan nanoparticles. By considering factors that represent optimal nanoparticles, the safe inactivated NDV nanoparticles were successfully developed. These results provide a foundation for the further development of mucosal vaccines based on inactivated antigens for use in chicken.