Formulation of Newcastle disease virus coupled calcium phosphate nanoparticles: an effective strategy for oculonasal delivery to chicken.

In this report, calcium phosphate (CaP) nanoparticles were synthesized by continuous flow method using β-cyclodextrin (β-CD) as a medium and functionalized with amino propyl triethoxy silane (APTES). The blood biocompatibility of the nanoparticles was assessed using the whole blood haemolysis, erythrocytes haemolysis and erythrocyte aggregation tests. Based on the results, we found that the synthesized β-CD-CaP nanoparticles did not cause any remarkable toxic effect. The 5-dimethylthiazol-2-yl-2, 5-diphenyltetrazolium bromide (MTT) assay of chicken peripheral blood mononucleated cells (PBMCs) incubated with these nanoparticles indicated that these particles did not exert any significant cytotoxicity. The aminosilane functional group modified β-CD-CaP was used as tool for coupling of Newcastle disease virus (NDV). The NDV conjugated nanoparticles were confirmed by using Fourier transformed infrared spectroscopy, X-ray diffraction patterns, Raman spectroscopy differential scanning calorimetry and energy-dispersive X-ray spectroscopy. Immunogenicity trials in chickens proved that β-CD-CaP-NDV used as a vaccine was better than the commercial vaccine when given oculonasally during the first 2 weeks post vaccination. The birds vaccinated with the above nano-NDV vaccine were completely protected against virulent NDV challenge. This study confirms that the oculonasal β-CD-CaP-NDV delivery of vaccines is a potential method for enhancing the immune responses of existing commercial vaccines.