Preparation Of Newcastle Disease Nanoparticle DNA Vaccine With Ag @ SiO 2 As The Carrier And Its Immune Effect

Newcastle disease (ND) is an acute, potent and highly contagious disease caused by Newcastle disease virus (NDV), which causes great harm to animal husbandry. It could bring great economic loss. Now the main method to prevent Newcastle disease is still the vaccine inoculation, such as attenuated vaccine and inactivated vaccine, but they have more or less shortcomings in practice. The effects of the cellular immunity and mucosal immunity were stimulated by inactivated ND vaccines were weak, and accompanied by vaccination reactions. While, attenuated vaccine may be atavistic because of mutation. DNA vaccines have been focused on because of the advantages of attenuated vaccine and the safety of nactivated vaccines. Although DNA vaccine is superior than traditional vaccines in some respects, but it is easy to be degraded, Targeting poor, More number of immunization. The disadvantages could be avoided when the nanopartciles mucosa immunity delivery system was built by biodegradable materials.In this study, the pFDNA-Ag@SiO2-NPs were obtained when biodegradable material Ag@SiO2 was chosen as drug carriers, ND DNA vaccine pVAXl-optiF was selected as the model drug. The physicochemical characters, stability, cell toxicity and immune effect of the pFDNA-Ag@SiO2-NPs were evaluated. The results demonstrated that:1) The results demonstrated that the pFDNA-Ag@SiO2-NPs had been produced with morphous regulation, integrated profile, smooth surface, suitable size. The average particle size of the pFDNA-Ag@SiO2-NPs was 511.33nm with low polydispersity index 0.246 and proper Zata Potential 9.62mV. The entrapment efficiency, was (70.96±5,74)%;2)Bacteriostatic test results showed that the Ag@SiO2 nanoparticles have different inhibitory effect on the Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Enterobacter cloacae, Moniliaalbican except of Enterobacter cloacae;3) DNase I digestion test showed that pFDNA-Ag@SiO2-NPs had the ability to protect DNA from DNase I degradation;4) The release behavior of pFDNA-Ag@SiO2-NPs test in vitro demonstrated that pFDNA-Ag@SiO2-NPs release was a continuous release process after initial burst release;5) The indirect immunofluorescence results showed that the preparation method of pFDNA-Ag@SiO2-NPs didn’t destroy the biological activity of plasmid DNA, which had expressed in vitro;6) The pFDNA-Ag@SiO2-NPs mucosal delivery system was low toxicity and excellent safety, which could be proved by a cytotoxicity test;7) The SPF chicken vaccination results showed that mucosal immunity by pFDNA-Ag@SiO2-NPs used, the IgG and IgA contents of mucosal immune response positions were higher than intramuscular injection. In addition, the IFN-y, IL-2, IL-4 concentrations of serum and Lymphocyte transformation rate after immunization had been rised. the IgG, IFN-y, IL-2, IL-4 concentrations of serum of mucosal immunity kept rising, and and protective efficacy was superior to intramuscular injection. In a word, the result proved that nanoparticles mucosal delivery system not only induced immune responses in mucosal location but also produced high systemic, humoral and cellular immune responses.ND DNA vaccine encapsulated in Ag@SiO2 nanoparticles had been assembled successfully, and the mucosal delivery system had implemented, a mechanism of the long-term mechanism of action in vivo, which could protect antigen form degradation, increase the vaccination methods, simplify the process of vaccination, decrease the vaccination times, enhance the immune effect. At the same time, the results also provided theoretical reference for developing a safe, efficient and better performance gene delivery vector.