Response of live Newcastle disease virus encapsulated in N -2-hydroxypropyl dimethylethyl ammonium chloride chitosan nanoparticles

Immunoprotective effect of chitosan nanoparticles with different particle sizes against H9N2 avian influenza infection

H9N2 is the most common avian influenza virus (AIV), which causes significant losses in chickens. Safe and effective vaccines are crucial for the prevention of H9N2 AIVs. Chitosan nanoparticles, as novel adjuvants, enhance vaccine immunity and biocompatibility; however, the impact of particle size on the immunological effects remains underexplored. To solve these problems and to prepare an efficient novel H9N2 vaccine, we constructed four N-2-HACC/CMCS NPs (NHC NPs) of different particle sizes (165.6 ± 12.0 nm, 272.5 ± 7.0 nm, 343.2 ± 8.0 nm, and 443.5 ± 15.0 nm). Subsequent in vivo immunogenicity screening revealed that H9N2 with the 272.5 ± 7.0 nm NHC NPs vaccine group induced higher levels of neutralizing antibodies in the early stage of the immune response, while the 343.2 ± 8.0 nm NHC NPs vaccine group induced higher levels of neutralizing antibodies in the late stages of the immune response. Subsequently, the results of the optimal particle size combination screening revealed that more neutralizing antibodies were induced when the NHC NPs particle size combination of 272.5 ± 7.0 nm:343.2 ± 8.0 nm ratio was 1.5:1. This optimal particle size combination for NP vaccines promoted lymphocyte proliferation, induced higher IgG2a/IgG1 ratios, and promoted the production of cytokines (i.e., IL-2, IL-4, and IFN-γ). Moreover, a mechanistic analysis revealed that the optimal NHC NPs combination triggered the activation of antigen presenting cells via TLR4 and participated in immune responses through the production of NO and TNF-α. Taken together, our study revealed that the optimal combination of NHC NPs may be a promising strategy against influenza viruses.

Mucosal immune responses and protective efficacy elicited by oral administration AMP-ZnONPs-adjuvanted inactivated H9N2 virus in chickens

The avian influenza virus is infected through the mucosal route, thus mucosal barrier defense is very important. While the inactivated H9N2 vaccine cannot achieve sufficient mucosal immunity, adjuvants are needed to induce mucosal and systemic immunity to prevent poultry from H9N2 influenza virus infection. Our previous study found that polysaccharide from Atractylodes macrocephala Koidz binding with zinc oxide nanoparticles (AMP-ZnONPs) had immune-enhancing effects in vitro. This study aimed to evaluate the mucosal immune responses of oral whole-inactivated H9N2 virus (WIV)+AMP-ZnONPs and its impact on the animal challenge protection, and the corresponding changes of pulmonary metabolomics after the second immunization. The results showed that compared to the WIV, the combined treatment of WIV and AMP-ZnONPs significantly enhanced the HI titer, IgG and specific sIgA levels, the number of goblet cells and intestinal epithelial lymphocytes (iIELs) as well as the expression of J-chain, polymeric immunoglobulin receptor (pIgR), interleukin-10 (IL-10), tumor necrosis factor-α (TNF-α) and transforming growth factor-β (TGF-β). In viral attack experiments, WIV combing with AMP-ZnONPs effectively reduced lung damage and viral titers in throat swabs. Interestingly, significant changes of both the IgA intestinal immune network and PPAR pathway could also be found in the WIV+AMP-ZnONPs group compared to the non-infected group. Taken together, these findings suggest that AMP-ZnONPs can serve as a potential mucosal vaccine adjuvant, thereby avoiding adverse stress and corresponding costs caused by vaccine injection.

Genetic Diversity of Newcastle Disease Virus Involved in the 2021 Outbreaks in Backyard Poultry Farms in Tanzania

Newcastle disease virus is a significant avian pathogen with the potential to decimate poultry populations all over the world and cause enormous economic losses. Distinct NDV genotypes are currently causing outbreaks worldwide. Due to the high genetic diversity of NDV, virulent strains that may result in a lack of vaccine protection are more likely to emerge and ultimately cause larger epidemics with massive economic losses. Thus, a more comprehensive understanding of the circulating NDV genotypes is critical to reduce Newcastle disease (ND) burden. In this study, NDV strains were isolated and characterized from backyard poultry farms from Tanzania, East Africa in 2021. Reverse-transcription polymerase chain reaction (RT-PCR) based on fusion (F) gene amplification was conducted on 79 cloacal or tracheal swabs collected from chickens during a suspected ND outbreak. Our results revealed that 50 samples out 79 (50/79; 63.3%) were NDV-positive. Sequencing and phylogenetic analyses of the selected NDV isolates showed that 39 isolates belonged to subgenotype VII.2 and only one isolate belonged to subgenotype XIII.1.1. Nucleotide sequences of the NDV F genes from Tanzania were closely related to recent NDV isolates circulating in southern Africa, suggesting that subgenotype VII.2 is the predominant subgenotype throughout Tanzania and southern Africa. Our data confirm the circulation of two NDV subgenotypes in Tanzania, providing important information to design genotype-matched vaccines and to aid ND surveillance. Furthermore, these results highlight the possibility of the spread and emergence of new NDV subgenotypes with the potential of causing future ND epizootics.

Chitosan-Based Nanomaterial as Immune Adjuvant and Delivery Carrier for Vaccines

With the support of modern biotechnology, vaccine technology continues to iterate. The safety and efficacy of vaccines are some of the most important areas of development in the field. As a natural substance, chitosan is widely used in numerous fields-such as immune stimulation, drug delivery, wound healing, and antibacterial procedures-due to its good biocompatibility, low toxicity, biodegradability, and adhesion. Chitosan-based nanoparticles (NPs) have attracted extensive attention with respect to vaccine adjuvants and delivery systems due to their excellent properties, which can effectively enhance immune responses. Here, we list the classifications and mechanisms of action of vaccine adjuvants. At the same time, the preparation methods of chitosan, its NPs, and their mechanism of action in the delivery system are introduced. The extensive applications of chitosan and its NPs in protein vaccines and nucleic acid vaccines are also introduced. This paper reviewed the latest research progress of chitosan-based NPs in vaccine adjuvant and drug delivery systems.

Amoxicillin encapsulated in the N-2-hydroxypropyl trimethyl ammonium chloride chitosan and N,O-carboxymethyl chitosan nanoparticles: Preparation, characterization, and antibacterial activity

This is a report on the encapsulation amoxicillin (AMX) in the N-2-Hydroxypropyl trimethyl ammonium chloride chitosan (N-2-HACC) and N,O-carboxymethyl chitosan (CMCS) nanoparticles (NPs) for biomedical applications. The N-2-HACC/CMCS NPs have broad-spectrum antibacterial properties. In order to achieve sustained and slow drug release, improve drug transport efficiency and bioavailability, prolong drug residence time, and reduce pollution, we synthesized highly efficient, easily absorbed and rapidly degradable nano-formulation veterinary antibiotics in this study. The N-2-HACC/CMCS NPs were used for the encapsulation of AMX, and the cytocompatibility, in vitro release, in vivo drug release kinetics and antimicrobial activity of N-2-HACC/CMCS/AMX NPs were investigated. The NPs displayed a round shape and smooth surface, and the NPs allowed the sustained release of AMX at a much slower rate than that of non-coated AMX. The NPs exhibited excellent cytocompatibility and the antimicrobial activity against Escherichia coli, Acinetobacter baumannii, Streptococcus pneumoniae and Staphylococcus aureus. Moreover, the NPs could store at 4 °C, -20 °C and 25 ± 5 °C for 30 d. These results suggested that the N-2-HACC/CMCS NPs could be availed as a candidate for drug delivery carrier to achieve sustained and slow release, improve bioavailability, prolong residence time at the target site, and reduce the dosage of drug.

Complexation behavior of carboxymethyl short-chain amylose and quaternized chitosan

The complexation of carboxymethyl short-chain amylose (CSA) and hydroxypropyl trimethyl ammonium chloride chitosan (HACC) and the stability of CSA/HACC nanocomplex were investigated. Resonance light scattering (RLS), turbidity, nanoparticle size and zeta potential analyses revealed that the complex coacervation occurred between CSA and HACC. The mass ratio and pH markedly influenced the complexation behavior; CSA with a higher degree of substitution (DS0.2) altered the complexation at a lower mass ratio and pH, increasing the turbidity and RLS intensity. The results of particle size and zeta potential analyses indicated that CSA/HACC complexes possessed the good pH and ionic strength stability. In addition to electrostatic interactions, hydrogen bonding and hydrophobic effects were also determined to be involved in the complexation process using thermal titration calorimetry (ITC). Additionally, the process was spontaneous, and CSA with a higher DS showed stronger complexation ability. These results may enable the understanding of polysaccharide complex behaviors.

The Potential of Chitosan in Nanomedicine: An Overview of the Cytotoxicity of Chitosan Based Nanoparticles

The unique properties and applications of nanotechnology in targeting drug delivery, cosmetics, fabrics, water treatment and food packaging have received increased focus the last two decades. The application of nanoparticles in medicine is rapidly evolving, requiring careful investigation of toxicity before clinical use. Chitosan, a derivative of the natural polysaccharide chitin, has become increasingly relevant in modern medicine because of its unique properties as a nanoparticle. Chitosan is already widely used as a food additive and in food packaging, bandages and wound dressings. Thus, with an increasing application worldwide, cytotoxicity assessment of nanoparticles prepared from chitosan is of great interest. The purpose of this review is to provide an updated status of cytotoxicity studies scrutinizing the safety of chitosan nanoparticles used in biomedical research. A search in Ovid Medline from 23 March 1998 to 4 January 2022, with the combination of the search words Chitosan or chitosan, nanoparticle or nano particle or nanosphere or nanocapsule or nano capsule, toxicology or toxic or cytotoxic and mucosa or mucous membrane resulted in a total of 88 articles. After reviewing all the articles, those involving non-organic nanoparticles and cytotoxicity assays conducted exclusively on nanoparticles with anti-tumor effect (i.e., having cytotoxic effect) were excluded, resulting in 70 articles. Overall, the chitosan nanoparticles included in this review seem to express low cytotoxicity regardless of particle composition or cytotoxicity assay and cell line used for testing. Nonetheless, all new chitosan derivatives and compositions are recommended to undergo careful characterization and cytotoxicity assessment before being implemented on the market.

Advanced approaches for improving bioavailability and controlled release of anthocyanins

Anthocyanins are a group of phytochemicals responsible for the purple or red color of plants. Additionally, they are recognized to have health promoting functions including anti-cardiovascular, anti-thrombotic, anti-diabetic, antimicrobial, neuroprotective, and visual protective effect as well as anti-cancer activities. Thus, consumption of anthocyanin supplement or anthocyanin-rich foods has been recommended to prevent the risk of development of chronic diseases. However, the low stability and bioavailability of anthocyanins limit the efficacy and distribution of anthocyanins in human body. Thus, strategies to achieve target site-local delivery with good bioavailability and controlled release rate are necessary. This review introduced and discussed the latest advanced techniques of designing lipid-based, polysaccharide-based and protein-based complexes, nano-encapsulation and exosome to overcome the limitation of anthocyanins. The improved bioavailability and controlled release of anthocyanins have great significance for gastrointestinal tract absorption, transepithelial transportation and cellular uptake. The techniques of applying different biocompatible materials and modifying the solubility of anthocyanins complex could achieve target site-local delivery with negligible degradation and good bioavailability in human body.

N-2-Hydroxypropyl Trimethyl Ammonium Chloride Chitosan as Adjuvant Enhances the Immunogenicity of a VP2 Subunit Vaccine against Porcine Parvovirus Infection in Sows

Porcine parvovirus (PPV) is the most important infectious agent causing infertility in pigs, which can be prevented by routine vaccination. Successful vaccination depends on the association with potent adjuvants that can enhance the immunogenicity of antigen and activate the immune system. Polysaccharide adjuvant has low toxicity and high safety, and they can enhance the humoral, cellular and mucosal immune responses. In the present study, we prepared the VP2 protein subunit vaccine against PPV (PPV/VP2/N-2-HACC) using water-soluble N-2-Hydroxypropyl trimethyl ammonium chloride chitosan (N-2-HACC) as the vaccine adjuvant, and the ability of the PPV/VP2/N-2-HACC to induce immune responses and protect sows from PPV infection was evaluated. In vivo immunization showed that the sows immunized with the PPV/VP2/N-2-HACC by intramuscular injection produced higher HI antibody levels and long-term immune protection compared with the other groups, while the subunit vaccine did not stimulate the proliferation of CD4+ and CD8+ T lymphocytes to trigger the secretion of higher levels of IL-2, IL-4, IFN-α, IFN-β, and IFN-γ, indicating that the PPV/VP2/N-2-HACC mainly induced humoral immunity rather than cellular immunity. PPV was not detected in the viscera of the sows immunized with the PPV/VP2/N-2-HACC, and the protective efficacy was 100%. Collectively, our findings suggested that the N-2-HACC was a potential candidate adjuvant, and the PPV/VP2/N-2-HACC had immense application value for the control of PPV.

Chitosan-Based Nanoparticles Against Viral Infections

Viral infections, in addition to damaging host cells, can compromise the host immune system, leading to frequent relapse or long-term persistence. Viruses have the capacity to destroy the host cell while liberating their own RNA or DNA in order to replicate within additional host cells. The viral life cycle makes it challenging to develop anti-viral drugs. Nanotechnology-based approaches have been suggested to deal effectively with viral diseases, and overcome some limitations of anti-viral drugs. Nanotechnology has enabled scientists to overcome the challenges of solubility and toxicity of anti-viral drugs, and can enhance their selectivity towards viruses and virally infected cells, while preserving healthy host cells. Chitosan is a naturally occurring polymer that has been used to construct nanoparticles (NPs), which are biocompatible, biodegradable, less toxic, easy to prepare, and can function as effective drug delivery systems (DDSs). Furthermore, chitosan is Generally Recognized as Safe (GRAS) by the US Food and Drug Administration (U.S. FDA). Chitosan NPs have been used in drug delivery by the oral, ocular, pulmonary, nasal, mucosal, buccal, or vaginal routes. They have also been studied for gene delivery, vaccine delivery, and advanced cancer therapy. Multiple lines of evidence suggest that chitosan NPs could be used as new therapeutic tools against viral infections. In this review we summarize reports concerning the therapeutic potential of chitosan NPs against various viral infections.

Chitosan Nanoparticles Loaded with Truncated ORF2 Protein as an Oral Vaccine Candidate against Hepatitis E

In a continuous effort to develop effective vaccines against hepatitis E (HE), oral vaccine nanoparticles using the truncated capsid protein p146 (aa460-605) are formulated and characterized. To improve the immunogenicity of p146, chitosan nanoparticles (CSNPs) are used as a mucosal delivery system. Next, the physical-chemical properties, cytotoxic effects in vitro, and immunogenicity in mice of the produced NPs are analyzed. The results show that the produced CS/p146 NPs are stable and well dispersive and display a near-spherical shape with a mean size of 200-300 nm. The findings also demonstrate high encapsulation efficiency (65-73.9%) and loading capacity (27.7-67.5%) of the formulated nanoparticles. Further, the CS/p146 NPs exhibit low cytotoxicity and an obvious sustained-release effect in vitro. Immunogenicity experiments in mice indicate that CS/p146 NPs can induce antigen-specific systemic and mucosal immune responses higher than the purified p146 do. Besides, the expression levels and mRNA transcription of Interleukin (IL)-4 in spleen cells of CS/p146 NPs-immunized mice are higher than those of p146, indicating that a Th2-mediated cellular immune response is activated by the CS/p146 NPs. Overall, the synthesized CS/p146 NPs display promising properties as a potential HE oral vaccine candidate.

Towards Improved Use of Vaccination in the Control of Infectious Bronchitis and Newcastle Disease in Poultry: Understanding the Immunological Mechanisms

Infectious bronchitis (IB) and Newcastle disease (ND) are two important diseases of poultry and have remained a threat to the development of the poultry industry in many parts of the world. The immunology of avian has been well studied and numerous vaccines have been developed against the two viruses. Most of these vaccines are either inactivated vaccines or live attenuated vaccines. Inactivated vaccines induce weak cellular immune responses and require priming with live or other types of vaccines. Advanced technology has been used to produce several types of vaccines that can initiate prime immune responses. However, as a result of rapid genetic variations, the control of these two viral infections through vaccination has remained a challenge. Using various strategies such as combination of live attenuated and inactivated vaccines, development of IB/ND vaccines, use of DNA vaccines and transgenic plant vaccines, the problem is being surmounted. It is hoped that with increasing understanding of the immunological mechanisms in birds that are used in fighting these viruses, a more successful control of the diseases will be achieved. This will go a long way in contributing to global food security and the economic development of many developing countries, given the role of poultry in the attainment of these goals.

Chitosan Nanoparticle Based Mucosal Vaccines Delivered Against Infectious Diseases of Poultry and Pigs

Infectious disease of poultry and pig are major threat to health and cause severe economic loss to the food industry and a global food safety issue. Poultry and pig act as a mixing vessel of zoonotic transmission of disease to humans. Effective mucosal vaccines used in animals could reduce the impact of diseases in food animals. Chitosan is a biocompatible polymer, and its positive charge makes it a natural mucoadhesive agent. Therefore, since last one-decade chitosan derived nanoparticles (CS NPs) have been in use widely to deliver vaccine antigens in animals through mucosal route. Primary route of entry of most infectious disease pathogen is through oral and nasal routes, and the CS NPs based vaccines delivered through that routes enhance the immunogenicity of encapsulated vaccine antigens by targeting the cargo to mucosal microfold cells, dendritic cells and macrophages. Resulting in induction of robust secretory and systemic antibodies and/or cell mediated immune response which provides protection against infections. To date, CS NPs is being widely used for mucosal vaccine delivery in poultry and pigs to control bacterial and viral infections, and tested in several preclinical trials for vaccine delivery in humans. In this review, we highlighted the progress so far made in using CS NPs as a vehicle for mucosal vaccine delivery against infectious and zoonotic diseases of poultry and pigs. Discussed about the need of CS NPs modifications, CS NPs based vaccines induced immune responses and its role in protection, and challenges in vaccination and future directions.

Sunflower seed oil combined with ginseng stem-leaf saponins as an adjuvant to enhance the immune response elicited by Newcastle disease vaccine in chickens

The present study was to evaluate the adjuvant effect of sunflower seed oil containing saponins extracted from the stem and leaf of Panax ginseng C.A. Meyer (E515-D) on the immune response induced by an inactivated Newcastle disease virus (NDV) in chickens. The results showed that E515-D promoted significantly higher serum NDV-specific HI and neutralizing antibody responses, IFN-γ and IL-4 levels, and lymphocyte proliferative responses to Con A, LPS, and NDV antigen than the conventional adjuvant Marcol 52. Different adjuvant effect between E515-D and Marcol 52 may be attributed to different genes expressed in two groups. Transcriptome analysis of splenocytes showed that there were 1198 differentially expressed genes (DEGs) with 539 up and 659 down regulated in E515-D group while 1395 DEGs with 697 up and 698 down regulated in Marcol 52 group in comparison with the control group. Analysis of gene ontology (GO) term and kyoto encyclopedia of Genes and Genomes (KEGG) pathways showed that the predominant immune related pathways included "Toll-like receptor signaling pathway", "NOD-like receptor signaling pathway", "C-type lectin receptor signaling pathway", and "Phosphatidylinositol signaling system" in E515-D group while Marcol 52 were "NOD-like receptor signaling pathway", "Phagosome", and "Lysosome", and the most relevant DEGs in E515-D group were STAT1, STAT2, PI3K, and IL-6. Considering the excellent adjuvant activity and vegetable origin, E515-D deserves further study as an adjuvant for vaccines used in food animals.

Quaternized Chitosan Nanoparticles in Vaccine Applications

Different natural and synthetic biodegradable polymers have been used in vaccine formulations as adjuvant and delivery system but have faced various limitations. Chitosan is a new delivery system with the potential to improve development of nano vaccines and drugs. However, chitosan is only soluble in acidic solutions of low concentration inorganic acids such as dilute acetic acid and dilute hydrochloric acid and in pure organic solvents, which greatly limits its application. Chemical modification of chitosan is an important way to improve its weak solubility. Quaternized chitosan not only retains the excellent properties of chitosan, but also improves its water solubility for a wider application. Recently, quaternized chitosan nanoparticles have been widely used in biomedical field. This review focuses on some quaternized chitosan nanoparticles, and points out the advantages and research direction of quaternized chitosan nanoparticles. As shown by the applications of quaternized chitosan nanoparticles as adjuvant and delivery carrier in vaccines, quaternized chitosan nanoparticles have promising potential in application for the development of nano vaccines in the future.

Mucosal vaccines: Strategies and challenges

Mucosal immunization has potential benefits over conventional parenteral immunization, eliciting immune defense in both mucosal and systemic tissue for protecting from pathogen invasion at mucosal surfaces. To provide a first line of protection at these entry ports, mucosal vaccines have been developed and hold a significant promise for reducing the burden of infectious diseases. However, until very recently, only limited mucosal vaccines are available. This review summarizes recent advances in selected aspects regarding mucosal vaccination, including appropriate administration routes, reasonable formulations, antigen-sampling and immune responses of mucosal immunity, and the strategies used to improve mucosal vaccine efficacy. Finally, the challenges of developing successful mucosal vaccines and the potential solutions are discussed.

Fabrication of Quaternized Chitosan Nanoparticles Using Tripolyphosphate/Genipin Dual Cross-Linkers as a Protein Delivery System

Various amounts of 2-((acryloyloxy)ethyl)trimethylammonium chloride were grafted onto chitosan (CS) via redox polymerization method to obtain water-soluble quaternized CS (QCS). The QCS nanoparticles loaded with bovine serum albumin (BSA) were then produced by ionic gelation with tripolyphosphate (TPP) and further covalently cross-linked with genipin. The formation of QCS nanoparticles was optimized as a function of monomer grafting yield, QCS/TPP weight ratio, and QCS/genipin weight ratio by Box-Behnken design and response surface methodology. The results showed that QCS nanoparticles prepared with a grafting yield of 50%, QCS/TPP weight ratio of 7.67, and QCS/genipin weight ratio of 60 had a particle size of 193.68 ± 44.92 nm, polydispersity of 0.232, zeta potential of +23.97 mV and BSA encapsulation efficiency of 46.37 ± 2.89%, which were close to the predicted values from mathematical models. In vitro drug release studies at pH 1.2 and pH 7.4 exhibited that the release rate of BSA was significantly decreased and the release period was significantly prolonged after QCS nanoparticles cross-linking with genipin. Therefore, QCS nanoparticles cross-linked with TPP/genipin dual cross-linkers may be a promising protein drug carrier for a prolonged and sustained delivery.

Polysaccharides as vaccine adjuvants

Adjuvant is a substance added to vaccine to improve the immunogenicity of antigens, and it can induce stronger immune responses and reduce the dosage and production cost of vaccine in populations responding poorly to vaccination. Adjuvants in development or in use mainly include aluminum salts, oil emulsions, saponins, immune-stimulating complexes, liposomes, microparticles, nonionic block copolymers, polysaccharides, cytokines and bacterial derivatives. Polysaccharide adjuvants have attracted much attention in the preparation of nano vaccines and nano drugs because natural polysaccharides have the characteristics of intrinsic immunomodulating, biocompatibility, biodegradability, low toxicity and safety. Moreover, it has been proved that a variety of natural polysaccharides possess better immune promoting effects, and they can enhance the effects of humoral, cellular and mucosal immunities. In the present study, we systematically reviewed the recent studies on polysaccharides with vaccine adjuvant activities, including chitosan-based nanoparticles (NPs), glucan, mannose, inulin polysaccharide and Chinese medicinal herb polysaccharide. The application and future perspectives of polysaccharides as adjuvants were also discussed. These findings lay a foundation for the further development of polysaccharide adjuvants. Collectively, more and more polysaccharide adjuvants will be developed and widely used in clinical practice with more in-depth investigations of polysaccharide adjuvants.

Biomedical Applications of Chitosan and Its Derivative Nanoparticles

Chitosan is a biodegradable natural polymer with many advantages such as nontoxicity, biocompatibility, and biodegradability. It can be applied in many fields, especially in medicine. As a delivery carrier, it has great potential and cannot be compared with other polymers. Chitosan is extremely difficult to solubilize in water, but it can be solubilized in acidic solution. Its insolubility in water is a major limitation for its use in medical applications. Chitosan derivatives can be obtained by chemical modification using such techniques as acylation, alkylation, sulfation, hydroxylation, quaternization, esterification, graft copolymerization, and etherification. Modified chitosan has chemical properties superior to unmodified chitosan. For example, nanoparticles produced from chitosan derivatives can be used to deliver drugs due to their stability and biocompatibility. This review mainly focuses on the properties of chitosan, chitosan derivatives, and the origin of chitosan-based nanoparticles. In addition, applications of chitosan-based nanoparticles in drug delivery, vaccine delivery, antimicrobial applications, and callus and tissue regeneration are also presented. In summary, nanoparticles based on chitosan have great potential for research and development of new nano vaccines and nano drugs in the future.

Enhancing Mucosal Immune Response of Newcastle Disease Virus DNA Vaccine Using N-2-Hydroxypropyl Trimethylammonium Chloride Chitosan and N,O-Carboxymethyl Chitosan Nanoparticles as Delivery Carrier

Because mucosal sites are the entry ports of pathogens, immunization via mucosal routes can extremely enhance the immunity. To elevate the potential of N-2-hydroxypropyl trimethylammonium chloride chitosan (N-2-HACC) and N,O-carboxymethyl chitosan (CMC) nanoparticles as a mucosal immune delivery carrier for DNA vaccines, we prepared the NDV F gene plasmid DNA with C3d6 molecular adjuvant (pVAX I-F(o)-C3d6) encapsulated in the N-2-HACC-CMC nanoparticles (N-2-HACC-CMC/pFDNA-C3d6 NPs). The N-2-HACC-CMC/pFDNA-C3d6 NPs had regular spherical morphology and low toxicity with a mean diameter of 309.7 ± 6.52 nm, zeta potential of 49.9 ± 4.93 mV, encapsulation efficiency of 92.27 ± 1.48%, and loading capacity of 50.75 ± 1.35%. The N-2-HACC-CMC had high stability and safety. The pVAX I-F(o)-C3d6 could be sustainably released from the N-2-HACC-CMC/pFDNA-C3d6 NPs after an initial burst release. Immunization intranasally of chickens with N-2-HACC-CMC/pFDNA-C3d6 NPs not only produced higher anti-NDV IgG and sIgA antibody than chickens in other groups did, but also significantly stimulated lymphocyte proliferation and triggered higher the IL-2, IL-4, and IFN-γ levels. These findings indicated that the N-2-HACC-CMC could be used as an efficient delivery carrier for the mucosal immunity of Newcastle disease virus DNA vaccine. The work laid a basis for the quaternized chitosan nanoparticles as efficient mucosal immunity delivery carrier for DNA vaccines and had immense application promise and potential for vaccines and drugs.