| Newcastle disease is a serious infectious viral disease ofpoultry. It can cause nervous, respiratory, enteric, and reproductive infections. ND has been a deadly disease and still is one of the main problems of poultry industries in most of countries. There is no effective treatment way ofND. However, vaccination is an effective way to control ND. The NDV live vaccines and inactivated live vaccines are used universally to control ND. However, these conventional vaccines have many drawbacks. Live vaccines have some limitations, including the need for biocontainment during production, cold chain requirements, and safety concerns due to the possibility of reversion. A major problem with the use of inactivated vaccines is that they generally have poor immunogenicity and can cause disease if they are not completely inactivated. DNA vaccines represent a promising technology because of their safety, genetic stability, ease of production, non-requirement for cold chain, and activation of innate immunity pathways. Now, intramuscular injection was the primary route for DNA vaccine administration. However, many studies indicated that after intramuscular injection, plasmid DNA is easy to be degraded by nuclease and it is difficult for the vaccines to move through cell membranes, so only a small amount reaches antigen-presenting cells (APCs) to induce immune responses. These disadvantages could be avoided when the nanopartciles mucosa immunity delivery system was built by biodegradable materials.The pFDNA-N-2-HACC/CMC-NPs were prepared according to a polyelectrolyte complex method.1) The pFDNA-N-2-HACC/CMC-NPs were produced with good morphology, high stability, an average diameter of 309.7±6.52 nm, encapsulation efficiency of 92.27±1.48%, load ing capacity of 92.27±1.48%, and a Zeta potential of 49.9 ±4.93 mV; 2) DNase I digestion test showed that pFDNA-N-2-HACC/CMC-NPs had the ability to protect DNA from DNase I degradation; 3) The in vitro release assay showed that the plasmid DNA was sustainably released from the pFDNA-N-2-HACC/CMC-NPs, up to 81.67±0.92% of the total amount; 4) Cell transfection test indicated that the vaccine expressed the F gene in cells and maintained good bioactivity; 5) Storage stability tests showed that no significant changes in the appearance of nanoparticles storage at 37 ℃,20 ℃,4 ℃,-20 ℃ for 3 weeks, and have good stability; 6) The safety of mucosal immunity delivery system of the pFDNA-N-2-HACC/CMC-NPs was also tested in vitro by cell cytotoxicity and in vivo by safety test in chickens; 7) In vivo immunization showed that better immune responses of specific pathogen-free chickens immunized with the pFDNA-N-2-HACC/CMC-NPs were induced, and prolonged release of the plasmid DNA was achieved compared to the chickens immunized with the control plasmid; 8) SPF chickens immunized intranasally experimental results showed that the pFDNA-N-2-HACC/CMC-NPs vaccines induced more long-lasting IgG antibodies, IgA antibody levels, IL-2, IL-4 and IFN-y secretion than intramuscular injection, immune chicken spleen lymphocyte transformation rate have increased significantly, and protective efficacy was superior to intramuscular injection.ND DNA vaccine encapsulated in N-2-HACC/CMC nanoparticles had been prepared, and the mucosal delivery system had implemented a mechanism ofthe long-term mechanism of action in vivo, which could protect antigen form degradation, increase the vaccination methods, simply the process of vaccination, decrease the vaccination times, enhance the immune effect.This study lays a foundation for the further development of mucosal vaccines and drugs encapsulated in N-2-HACC/CMC nanoparticles.
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