Adjuvanted quaternized chitosan composite aluminum nanoparticles-based vaccine formulation promotes immune responses in chickens

Nano/Micro-Enabled Modification and Innovation of Conventional Adjuvants for Next-Generation Vaccines

The global spread of infectious diseases has raised public awareness of vaccines, highlighting their essential role in protecting public health. Among the components of modern vaccines, adjuvants have received increasing attention for boosting immune responses and enhancing efficacy. Recent advancements in adjuvant research, particularly nanodelivery systems, have paved the way for developing more effective and safer adjuvants. This review outlines the properties, progress, and mechanisms of FDA-approved conventional adjuvants, focusing on their contributions to and challenges in vaccine success. Despite these advancements, conventional adjuvants still face suboptimal immunomodulatory effects, potential side effects, and limitations in targeting specific immune pathways. Nanodelivery systems have emerged as a transformative approach in adjuvant design, offering unique advantages such as enhancing vaccine stability, enabling controlled antigen release, and inducing specific immune responses. By addressing these limitations, nanocarriers improve the safety and efficacy of conventional adjuvants and drive the development of next-generation adjuvants for complex diseases. This review also explores strategies for incorporating nanodelivery systems into adjuvant development, emphasizing its role in optimizing vaccine formulations. By summarizing current challenges and recent advances, this review aims to provide valuable insights guiding future efforts in designing innovative adjuvants that meet the evolving needs of global immunization programs.

Animal vaccine revolution: Nanoparticle adjuvants open the future of vaccinology

In recent years, the rapid development of nanoparticle adjuvants has greatly facilitated the treatment and prevention of infectious diseases in humans and animals. The remarkable success of mRNA nanovaccines against SARS-CoV-2 has accelerated the advancement of nanoparticle adjuvant technologies in the era of precision medicine. Significant progress has been made in researching nanovaccines for major animal infectious diseases, such as porcine epidemic diarrhea, avian influenza, porcine reproductive and respiratory syndrome, bovine viral diarrhea, foot-and-mouth disease, African swine fever, and Newcastle disease. This article reviews the nanoparticle adjuvants under investigation for animal use, emphasizing their diverse mechanisms of action and immunological properties, and analyzes the physicochemical factors influencing their immune-enhancing effects. On this basis, we discuss future prospects and key challenges that need to be addressed, aiming to provide valuable references for the development of novel animal vaccine adjuvants.

Naringenin as a phytogenic adjuvant systematically enhances the protective efficacy of H9N2 inactivated vaccine through coordinated innate-adaptive immune priming in chickens

Although inactivated vaccines remain the primary strategy for preventing and controlling avian influenza virus, they fail to induce durable and systemic immune protection. Adjuvants are crucial for enhancing antigen immunogenicity and improving immune responses. In this study, we evaluated the adjuvant activity of naringenin (Nar) for H9N2 inactivated vaccine by detecting humoral immunity, cellular immunity, and viral challenge. The results demonstrated that Nar/H9N2 co-administration significantly increased IgG levels and hemagglutination inhibition (HI) titers. Nar/H9N2 promoted the formation of high-affinity antibodies by upregulating the expression of genes associated with B cell activation and germinal centers (GCs) formation, thus facilitating humoral immune responses. Concurrently, Nar/H9N2 vaccine enhanced T cell proliferation, CD4+and CD8+T cell differentiation, and the expression of Th1/Th2 cytokines, thereby promoting cellular immunity. Crucially, compared to the inactivated H9N2 vaccine alone, viral challenge experiments confirmed that Nar-adjuvanted immunization confers superior protection, markedly reducing viral shedding and minimizing damage to the trachea and lungs. These findings elucidate the capacity of naringenin to synchronize multifaceted immune activation through GCs optimization and T-cell modulation, establishing Nar as a viable candidate for poultry vaccine adjuvants.

Research publications and global manufacture of veterinary vaccines against avian influenza A (2019-2023)

The characteristics of the avian influenza virus and its worldwide spread have led to intense and unprecedented scientific activity and industrial production for preventive veterinary vaccines. However, knowledge gaps remain regarding the best strategies to prevent epidemiological events in the future. In this context, the present study aimed to provide a global analysis on the scientific and industrial production of avian influenza type A vaccines for farm animals and pets during the period 2019 2023. The Scopus database was used as the primary source of information (12,162 keywords, 2,437 scientific articles, 659 academic journals, and 46 countries) for the academic analysis, while technical information posted on official institutional websites (136 commercial formulations, 24 vaccines manufacturers, and 17 countries) was collected to conduct the industrial analysis. 3,045, 25.0%) exhibited the highest levels of co-occurrence in the sciences; the journal Vaccine was the most productive in terms of articles (11.8%, 288/2,437), and the countries with the most publications were the USA (25.5%, 622/2,437) and China (23.1%, 564/2,437). The most internationally marketed vaccines were inactivated (86.0%, 117/136), avian (47.1%, 64/136), and combined (52.2%, 71/136) vaccines as well as those containing Newcastle antigens (38.0%, 27/71). In conclusion, the study demonstrated the fundamental role of classical production methods (based on the use of the whole pathogen) in avian influenza A research and the production of veterinary vaccines.

Metal-Phenolic Network Hydrogel Vaccine Platform for Enhanced Humoral Immunity against Lethal Rabies Virus

Rabies, caused by rabies virus (RABV), is a zoonotic disease with a high mortality rate that has attracted global attention with the goal of eradication by 2030. However, rabies can only be prevented by appropriate and multiple vaccinations, which impede widespread vaccination in developing countries due to its high expenditure. Designing single-dose vaccines is a pressing challenge in the prevention of rabies and other infectious diseases. Herein, a metal-phenolic network (MPN)-based hydrogel vaccine (designated as CGMR) was developed to stimulate potent humoral immunity against RABV infection by a single immunization, resulting in 4.3-fold and 1.8-fold enhancements of virus-neutralizing antibody compared with that induced by inactivated RABV and alum adjuvant. The CGMR, cross-linked by phenol-modified chitosan with manganese ion, could prolong residence time by confining the antigen to the network of hydrogel, acting as a "hydrogel antigen depot". It also stimulated the activation of the cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-stimulator of interferon gene (STING) pathway, facilitating dendritic cell maturation and antigen presentation. The vaccine formulation recruited immunocytes and activated the germinal center, enhancing and sustaining humoral immune responses against the virulent RABV challenge. Collectively, this injectable manganese-based hydrogel vaccine provides a universal and ideal avenue for rabies and other infectious diseases.

Advances in Chitosan Derivatives: Preparation, Properties and Applications in Pharmacy and Medicine

Chitosan (CS) derivatives have been extensively investigated to enhance the physicochemical and biological properties of CS, such as its solubility, biocompatibility, and bioactivity, which are required in various areas of pharmacy and medicine. The present work emphasizes the ongoing research and development in this field, suggesting that the further exploration of CS derivatives could lead to innovative solutions that benefit society. The physicochemical properties, biological activities, methods of preparation, advantages, limitations, intended application areas, and realized practical implementations of particular CS derivatives are summarized and discussed herein. Despite the numerous promising attributes of CS derivatives as reported in this paper, however, challenges like target selectivity, standardization (purity, chitosan structural variability), and cost-effectiveness still need addressing for widespread implementation, especially in drug delivery. Therefore, basic research studies still prevail in CS drug delivery systems. However, for specific applications such as wound healing and tissue engineering, implementations of CS derivatives in practice are found to be more frequent. To obtain a more complex view of the topic, information from the scientific papers reviewed is supplemented with information from actual patents and clinical studies. Both basic research advances and the most successful and important medical implementations of CS derivatives are discussed concerning further challenges and future perspectives.

Improved cellular immune response induced by intranasal boost immunization with chitosan coated DNA vaccine against H9N2 influenza virus challenge

The H9N2 avian influenza virus (AIV) is spreading worldwide. Presence of H9N2 virus tends to increase the chances of infection with other pathogens which can lead to more serious economic losses. In a previous study, a regulated delayed lysis Salmonella vector was used to deliver a DNA vaccine named pYL233 encoding M1 protein, mosaic HA protein and chicken GM-CSF adjuvant. To further increase its efficiency, chitosan as a natural adjuvant was applied in this study. The purified plasmid pYL233 was coated with chitosan to form a DNA containing nanoparticles (named CS233) by ionic gel method and immunized by intranasal boost immunization in birds primed by oral administration with Salmonella strain. The CS233 DNA nanoparticle has a particle size of about 150 nm, with an encapsulation efficiency of 93.2 ± 0.12 % which protected the DNA plasmid from DNase I digestion and could be stable for a period of time at 37°. After intranasal boost immunization, the CS233 immunized chickens elicited higher antibody response, elevated CD4+ T cells and CD8+ T cells activation and increased T-lymphocyte proliferation, as well as increased productions of IL-4 and IFN-γ. After challenge, chickens immunized with CS233 resulted in the lowest levels of pulmonary virus titer and viral shedding as compared to the other challenge groups. The results showed that the combination of intranasal immunization with chitosan-coated DNA vaccine and oral immunization with regulatory delayed lytic Salmonella strain could enhance the immune response and able to provide protection against H9N2 challenge.

In vivo immunological activity of chitosan-derived nanoparticles

Chitosan has been studied as an immunomodulator, but few studies have used chitosan derivatives as adjuvants alone. After a preliminary study, we found that nanoparticles prepared from chitosan derivatives had better cellular immune activity when used as an adjuvant. Therefore, animal experiments were conducted to further investigate the performance and mechanism of these nanoparticles as immune adjuvants. We injected mice with the chitosan nanoparticle vaccine and measured the expression levels of immunoglobulins, immune factors, and immune genes in tissues and tissue sections. The results showed that C236-HACC-OVA (C2,3,6-chitosan sulfate-chitosan quaternary ammonium salt-ovalbumin) and NO-HACC-OVA (NO-carboxymethyl chitosan-chitosan quaternary ammonium salt-ovalbumin) nanoparticles can significantly improve the secretion of the immune factors IL-6, TNF, and IL-1β. The level of IgG1 was highly significant after administering both nanoparticles, but IgG2 was not significant in mice. Three immune factors (IL-4, IL-6, and IL-17) were secreted at high levels in mouse serum at a nanoparticle dose of 0.3 mg/mouse. These nanoparticles also have high safety in the liver, kidney, and spleen of mice. This study proves the possibility of using chitosan derivative nanoparticles as vaccine adjuvants. These data further indicate that chitosan derivative nanoparticles have potential for use as vaccine adjuvants and demonstrate that polysaccharides have a unique position in green vaccine research.

Advances in Poultry Vaccines: Leveraging Biotechnology for Improving Vaccine Development, Stability, and Delivery

With the rapidly increasing demand for poultry products and the current challenges facing the poultry industry, the application of biotechnology to enhance poultry production has gained growing significance. Biotechnology encompasses all forms of technology that can be harnessed to improve poultry health and production efficiency. Notably, biotechnology-based approaches have fueled rapid advances in biological research, including (a) genetic manipulation in poultry breeding to improve the growth and egg production traits and disease resistance, (b) rapid identification of infectious agents using DNA-based approaches, (c) inclusion of natural and synthetic feed additives to poultry diets to enhance their nutritional value and maximize feed utilization by birds, and (d) production of biological products such as vaccines and various types of immunostimulants to increase the defensive activity of the immune system against pathogenic infection. Indeed, managing both existing and newly emerging infectious diseases presents a challenge for poultry production. However, recent strides in vaccine technology are demonstrating significant promise for disease prevention and control. This review focuses on the evolving applications of biotechnology aimed at enhancing vaccine immunogenicity, efficacy, stability, and delivery.

Immune cell receptor-specific nanoparticles as a potent adjuvant for nasal split influenza vaccine delivery

Mucosal delivery systems have gained much attention as effective way for antigen delivery that induces both systemic and mucosal immunity. However, mucosal vaccination faces the challenges of mucus barrier and effective antigen uptake and presentation. In particular, split, subunit and recombinant protein vaccines that do not have an intact pathogen structure lack the efficiency to stimulate mucosal immunity. In this study, poly (lactic acid-co-glycolic acid-polyethylene glycol) (PLGA-PEG) block copolymers were modified by mannose to form a PLGA-PEG-Man conjugate (mannose modified PLGA-PEG), which were characterized. The novel nanoparticles (NPs) prepared with this material had a particle size of about 150 nm and a zeta potential of -15 mV, and possessed ideal mucus permeability, immune cell targeting, stability and low toxicity. Finally, PLGA-PEG-Man nanoparticles (PLGA-PEG-Man NPs) were successfully applied for intranasal delivery of split influenza vaccine in rat for the first time, which triggered strong systemic and mucosal immune responses. These studies suggest that PLGA-PEG-Man NPs could function as competitive potential nano-adjuvants to address the challenge of inefficient mucosal delivery of non-allopathogenic antigens.

Development and Optimal Immune Strategy of an Alum-Stabilized Pickering emulsion for Cancer Vaccines

Therapeutic cancer vaccines are considered as one of the most cost-effective ways to eliminate cancer cells. Although many efforts have been invested into improving their therapeutic effect, transient maturation and activations of dendritic cells (DCs) cause weak responses and hamper the subsequent T cell responses. Here, we report on an alum-stabilized Pickering emulsion (APE) that can load a high number of antigens and continue to release them for extensive maturation and activations of antigen-presenting cells (APCs). After two vaccinations, APE/OVA induced both IFN-γ-secreting T cells (Th1) and IL-4-secreting T cells (Th2), generating effector CD8⁺ T cells against tumor growth. Additionally, although they boosted the cellular immune responses in the spleen, we found that multiple administrations of cancer vaccines (three or four times in 3-day intervals) may increase the immunosuppression with more PD-1⁺ CD8⁺ and LAG-3⁺ CD8⁺ T cells within the tumor environment, leading to the diminished overall anti-tumor efficacy. Combining this with anti-PD-1 antibodies evidently hindered the suppressive effect of multiple vaccine administrations, leading to the amplified tumor regression in B16-OVA-bearing mice.