Gold nanoparticle-M2e conjugate coformulated with CpG induces protective immunity against influenza A virus

AuNP-M2e + sCpG vaccination of juvenile mice generates lifelong protective immunity to influenza A virus infection

Background

Influenza virus infection causes significant morbidity and mortality worldwide. Humans fail to make a universally protective memory response to influenza A because of high mutation rates in the immune-dominant influenza epitopes. We seek the development of a universal influenza A vaccine. The extracellular domain of the M2-ion channel (M2e) is an ideal antigenic target, as it is highly conserved, has a low mutation rate, and is essential for viral entry and replication. Considering the potential of a universal influenza vaccine for lifelong protection, we aimed to examine this potential using a recently published gold nanoparticle M2e vaccine with CpG as an adjuvant (AuNP-M2e + sCpG). Intranasal vaccination induces an M2e-specific memory response, which is protective against lethal infection with H1N1, H3N2, and H5N1 serotypes, in young BALB/c mice. Protection with AuNP-M2e + sCpG has been published up to 8 months after vaccination. However, the highest risk population during most influenza seasons is adults over 65 years old. Additionally, the efficacy of many vaccines decrease after aging and requiring booster vaccinations to remain effective.

Results

To determine if the AuNP-M2e + sCpG vaccine is a viable option as a universal vaccination capable of protection through geriatric age, we tested if the AuNP-M2e + sCpG vaccination loses efficacy after aging mice to geriatric age (over 18 months). Our data shows that mice aged 15 months after vaccination (~ 18-21 months old) retain significant M2e-specific antibody titers in total IgG, IgG1, IgG2a, and IgG2b. These mice are significantly protected from lethal influenza challenge (H1N1, 8.3 PFU). Further, these antibody titers increase upon infection with influenza A and remain elevated for 3 months, suggesting the elderly mice retain effective M2e-specific memory B cells.

Conclusions

Our results demonstrate that protective M2e-specific memory in mice developed at a young age can persist until geriatric age. Additionally, this memory is protective and M2e-specific B cells produced by vaccination with AuNP-M2e + sCpG are maintained and functional. If the results of this study persist in humans, they suggest that a universal influenza A vaccine could be administered early in life and maintain lifelong protection into geriatric age.

Development of a Gold Nanoparticle Vaccine against Enterohemorrhagic Escherichia coli O157:H7

Enterohemorrhagic E. coli O157:H7 is a human pathogen and the causative agent of diarrhea and hemorrhagic colitis, which can progress to hemolytic uremic syndrome. These complications represent a serious global public health problem that requires laborious public health interventions and safety control measures to combat recurrent outbreaks worldwide. Today, there are no effective interventions for the control of EHEC infections, and, in fact, the use of antibiotics is counterindicated for EHEC disease. Therefore, a viable alternative for the prevention of human infections is the development of vaccines; however, no such vaccines are approved for human use. In this study, we developed a novel gold nanoparticle platform which acts as a scaffold for the delivery of various antigens, representing a nanovaccine technology which can be applied to several disease models.

Here we exploit the natural properties of a synthetic nanoparticle (NP) scaffold as a subunit vaccine against enterohemorrhagic Escherichiacoli (EHEC). Two EHEC-specific immunogenic antigens, namely, LomW and EscC, either alone or in combination, were covalently linked on the surface of gold nanoparticles (AuNPs) and used to immunize mice prior to challenge with EHEC O157:H7 strain 86-24. LomW is a putative outer membrane protein encoded in bacteriophage BP-933W, while EscC is a structural type III secretion system protein which forms a ring in the outer membrane. The resulting AuNP preparations, AuNP-LomW and AuNP-EscC, showed that the nanoparticles were able to incorporate the antigens, forming stable formulations that retained robust immunogenicity in vivo after subcutaneous immunization. When administered subcutaneously, AuNP-LomW or AuNP-EscC or a combination containing equivalent amounts of both candidates resulted in higher IgG titers in serum and secretory IgA titers in feces. The serum IgG titers correlated with a significant reduction in EHEC intestinal colonization after 3 days postinoculation. In addition, we showed that serum from antigen-coated AuNP-immunized mice resulted in a reduction of adherence to human intestinal epithelial cells for EHEC, as well as for two other E. coli pathotypes (enteropathogenic E. coli [EPEC], encoding EscC, and enteroaggregative E. coli [EAEC], encoding LomW). Further, the serum had antigen-specific bactericidal properties, engaging the classical complement pathway. Overall, our results demonstrate the immunogenicity and stability of a novel nanovaccine against EHEC. These results also strengthen the prospect of development of a synthetic nanoparticle vaccine conjugated to E. coli antigens as a promising platform against other enteric pathogens.

Designing inorganic nanomaterials for vaccines and immunotherapies

Vaccines and immunotherapies have changed the face of health care. Biomaterials offer the ability to improve upon these medical technologies through increased control of the types and concentrations of immune signals delivered. Further, these carriers enable targeting, stability, and delivery of poorly soluble cargos. Inorganic nanomaterials possess unique optical, electric, and magnetic properties, as well as defined chemistry, high surface-to-volume- ratio, and high avidity display that make this class of materials particularly advantageous for vaccine design, cancer immunotherapy, and autoimmune treatments. In this review we focus on this understudied area by highlighting recent work with inorganic materials - including gold nanoparticles, carbon nanotubes, and quantum dots. We discuss the intrinsic features of these materials that impact the interactions with immune cells and tissue, as well as recent reports using inorganic materials across a range of emerging immunological applications.

A Universal Influenza Nanovaccine for "Mixing Vessel" Hosts Confers Potential Ability to Block Cross-Species Transmission

Influenza A virus (IAV), a deadly zoonotic pathogen, poses a tremendous threat and burden to global health systems. Pigs act as "mixing vessel" hosts to support and generate new pandemic viruses. Preventing the spread of IAV in pigs effectively can delay or even block cross-species transmission. Universal vaccines based on the highly conserved ectodomain of influenza matrix protein 2 (M2e) have been widely reported, but have not been applied due to inadequate protection. Porcine circovirus type 2 (PCV2) causes immunosuppression and promotes swine influenza virus (SIV) infection. Here, M2e is inserted into capsid protein of PCV2 without burying the neutralizing epitopes and self-assembles to form a bivalent nanovaccine. Inoculation with the nanovaccine induces robust M2e- and PCV2-specific immune responses. The nanovaccine confers protection against lethal challenges of IAV from different species in mice, and significantly reduces SIV titers in pigs' respiratory tract and blocks SIV transmission. These results indicate that the nanovaccine is an economical and promising PCV2 and universal IAV bivalent vaccine, and it will synergistically and powerfully offer potential ability to block IAV cross-species reassortment and transmission.

Chemical modification of enveloped viruses for biomedical applications

The unique characteristics of enveloped viruses including nanometer size, consistent morphology, narrow size distribution, versatile functionality and biocompatibility have attracted attention from scientists to develop enveloped viruses for biomedical applications. The biomedical applications of the viral-based nanoparticles include vaccine development, imaging and targeted drug delivery. The modification of the structural elements of enveloped viruses is necessary for the desired functions. Here, we review the chemical approaches that have been utilized to develop bionanomaterials based on enveloped viruses for biomedical applications. We first provide an overview of the structures of enveloped viruses which are composed of nucleic acids, structural and functional proteins, glycan residues and lipid envelope. The methods for modification, including direct conjugation, metabolic incorporation of functional groups and peptide tag insertion, are described based on the biomolecular types of viral components. Layer-by-layer technology is also included in this review to illustrate the non-covalent modification of enveloped viruses. Then, we further elaborate the applications of chemically-modified enveloped viruses, virus-like particles and viral subcomponents in biomedical research.

Innovative Mucosal Vaccine Formulations Against Influenza A Virus Infections

Despite efforts made to develop efficient preventive strategies, infections with influenza A viruses (IAV) continue to cause serious clinical and economic problems. Current licensed human vaccines are mainly inactivated whole virus particles or split-virion administered via the parenteral route. These vaccines provide incomplete protection against IAV in high-risk groups and are poorly/not effective against the constant antigenic drift/shift occurring in circulating strains. Advances in mucosal vaccinology and in the understanding of the protective anti-influenza immune mechanisms suggest that intranasal immunization is a promising strategy to fight against IAV. To date, human mucosal anti-influenza vaccines consist of live attenuated strains administered intranasally, which elicit higher local humoral and cellular immune responses than conventional parenteral vaccines. However, because of inconsistent protective efficacy and safety concerns regarding the use of live viral strains, new vaccine candidates are urgently needed. To prime and induce potent and long-lived protective immune responses, mucosal vaccine formulations need to ensure the immunoavailability and the immunostimulating capacity of the vaccine antigen(s) at the mucosal surfaces, while being minimally reactogenic/toxic. The purpose of this review is to compile innovative delivery/adjuvant systems tested for intranasal administration of inactivated influenza vaccines, including micro/nanosized particulate carriers such as lipid-based particles, virus-like particles and polymers associated or not with immunopotentiatory molecules including microorganism-derived toxins, Toll-like receptor ligands and cytokines. The capacity of these vaccines to trigger specific mucosal and systemic humoral and cellular responses against IAV and their (cross)-protective potential are considered.

Nano-based approach to combat emerging viral (NIPAH virus) infection

Emergence of new virus and their heterogeneity are growing at an alarming rate. Sudden outburst of Nipah virus (NiV) has raised serious question about their instant management using conventional medication and diagnostic measures. A coherent strategy with versatility and comprehensive perspective to confront the rising distress could perhaps be effectuated by implementation of nanotechnology. But in concurrent to resourceful and precise execution of nano-based medication, there is an ultimate need of concrete understanding of the NIV pathogenesis. Moreover, to amplify the effectiveness of nano-based approach in a conquest against NiV, a list of developed nanosystem with antiviral activity is also a prerequisite. Therefore the present review provides a meticulous cognizance of cellular and molecular pathogenesis of NiV. Conventional as well several nano-based diagnosis experimentations against viruses have been discussed. Lastly, potential efficacy of different forms of nano-based systems as convenient means to shield mankind against NiV has also been introduced.

Nanoparticle-Based Vaccines Against Respiratory Viruses

The respiratory mucosa is the primary portal of entry for numerous viruses such as the respiratory syncytial virus, the influenza virus and the parainfluenza virus. These pathogens initially infect the upper respiratory tract and then reach the lower respiratory tract, leading to diseases. Vaccination is an affordable way to control the pathogenicity of viruses and constitutes the strategy of choice to fight against infections, including those leading to pulmonary diseases. Conventional vaccines based on live-attenuated pathogens present a risk of reversion to pathogenic virulence while inactivated pathogen vaccines often lead to a weak immune response. Subunit vaccines were developed to overcome these issues. However, these vaccines may suffer from a limited immunogenicity and, in most cases, the protection induced is only partial. A new generation of vaccines based on nanoparticles has shown great potential to address most of the limitations of conventional and subunit vaccines. This is due to recent advances in chemical and biological engineering, which allow the design of nanoparticles with a precise control over the size, shape, functionality and surface properties, leading to enhanced antigen presentation and strong immunogenicity. This short review provides an overview of the advantages associated with the use of nanoparticles as vaccine delivery platforms to immunize against respiratory viruses and highlights relevant examples demonstrating their potential as safe, effective and affordable vaccines.

Prospects for the use of spherical gold nanoparticles in immunization

Recent years have seen extremely fast development of new viral nanovaccines and diagnostic agents using nanostructures prepared by biological and chemical synthesis. We used spherical gold nanoparticles (average diameter, 15 nm) as a platform for the antigen for swine transmissible gastroenteritis virus (TGEV). The literature data demonstrate that immunization of animals with the TGEV antigen coupled to gold nanoparticles (GNPs) not only activates antigen-presenting cells but also increases the proliferative activity of splenic lymphoid (antibody-forming) cells. The contents of γ-IFN, IL-1β, and IL-6 in animals immunized with GNP-antigen conjugates were found to be higher than those in intact animals or in animals given the antigen alone. The increased concentration of IL-1β in the immunized animals directly correlated with the activity of macrophages and stimulated B cells, which produce this cytokine when activated. The increased concentration of IL-6 indicates that the injected preparations are stimulatory to cellular immunity. Immunization with the TGEV antigen conjugated to GNPs as a carrier activates the respiratory activity of lymphoid cells and peritoneal macrophages, which is directly related to their transforming activity and to the activation of antibody generation. Furthermore, the use of this conjugate allows marked improvement of the structure of the animals' immune organs and restores the morphological-functional state of these organs. The microanatomical changes (increased number of follicles) indicate the activation of the B-dependent zone of the spleen and, consequently, the development of a humoral-type immunological reaction. The degradative processes observed in the animals immunized with TGEV antigen alone are evidence of weak resistance to pathogen attack. These results can be used to develop vaccines against this infection by employing TGEV antigen coupled to gold nanoparticles as a carrier.

A Perspective on Nanoparticle Universal Influenza Vaccines

Annually recurring seasonal influenza causes massive economic loss and poses severe threats to public health worldwide. The current seasonal influenza vaccines are the most effective means of preventing influenza infections but possess major weaknesses. Seasonal influenza vaccines require annual updating of the vaccine strains. However, it is an unreachable task to accurately predict the future circulating strains. Vaccines with mismatched strains dramatically compromise the vaccine efficacy. In addition, the seasonal influenza vaccines are ineffective against an unpredictable pandemic. A universal influenza vaccine would overcome these weaknesses of the seasonal vaccines and abolish the threat of influenza pandemics. One approach under investigation is to design influenza vaccine immunogens based on conserved, type-specific amino acid sequences and conformational epitopes, rather than strain-specific. Such vaccines can elicit broadly reactive humoral and cellular immunity. Universal influenza vaccine development has intensively employed nanotechnology because the structural and morphological properties of nanoparticles dramatically improve vaccine immunogenicity and the induced immunity duration. Layered protein nanoparticles can decrease off-target immune responses, fine-tune antigen recognition and processing, and facilitate comprehensive immune response induction. Herein, we review the designs of effective nanoparticle universal influenza vaccines, the recent discoveries of specific nanoparticle features that contribute to immunogenicity enhancement, and recent progress in clinical trials.

Investigation of tunable acetalated dextran microparticle platform to optimize M2e-based influenza vaccine efficacy

Influenza places a significant health and economic burden on society. Efficacy of seasonal influenza vaccines can be suboptimal due to poor matching between vaccine and circulating viral strains. An influenza vaccine that is broadly protective against multiple virus strains would significantly improve vaccine efficacy. The highly conserved ectodomain of matrix protein 2 (M2e) and 3'3' cyclic GMP-AMP (cGAMP) were selected as the antigen and adjuvant, respectively, to develop the basis for a potential universal influenza vaccine. The magnitude and kinetics of adaptive immune responses can have great impact on vaccine efficacy. M2e and cGAMP were therefore formulated within acetalated dextran (Ace-DEX) microparticles (MPs) of varying degradation profiles to examine the effect of differential vaccine delivery on humoral, cellular, and protective immunity. All Ace-DEX MP vaccines containing M2e and cGAMP elicited potent humoral and cellular responses in vivo and offered substantial protection against a lethal influenza challenge, suggesting significant vaccine efficacy. Serum antibodies from Ace-DEX MP vaccinated mice also demonstrated cross reactivity against M2e sequences of various viral strains, which indicates the potential for broadly protective immunity. Of all the formulations tested, the slowest-degrading M2e or cGAMP MPs elicited the greatest antibody production, cellular response, and protection against a viral challenge. This indicated the importance of flexible control over antigen and adjuvant delivery. Overall, robust immune responses, cross reactivity against multiple viral strains, and tunable delivery profiles make the Ace-DEX MP platform a powerful subunit vaccine delivery system.

Combination of M2e peptide with stalk HA epitopes of influenza A virus enhances protective properties of recombinant vaccine

Background

Influenza infection could be more effectively controlled if a multi-purpose vaccine with the ability to induce responses against most, or all, influenza A subtypes could be generated. Conserved viral proteins are a promising basis for the creation of a broadly protective vaccine. In the present study, the immunogenicity and protective properties of three recombinant proteins (vaccine candidates), comprising conserved viral proteins fused with bacterial flagellin, were compared.

Methods

Balb/c mice were immunized intranasally with recombinant proteins comprising either one viral protein (the ectodomain of the M2 protein, ‘M2e’) or two viral proteins (M2e and the hemagglutinin second subunit ‘HA2’ epitope) genetically fused with flagellin. Further, two different consensus variants of HA2 were used. Therefore, three experimental positives were used in addition to the negative control (Flg-his). The mucosal, humoral, and T-cell immune responses to these constructs were evaluated.

Result

We have demonstrated that insertion of the HA2 consensus polypeptide (aa 76–130), derived from either the first (HA2-1) or second (HA2-2) virus phylogenetic group, into the recombinant Flg4M2e protein significantly enhanced its immunogenicity and protective properties. Intranasal administration of the vaccine candidates (Flg-HA2-2-4M2e or Flg-HA2-1-4M2e) induced considerable mucosal and systemic responses directed at both the M2e-protein and, in general, the influenza A virus. However, the immune response elicited by the Flg-HA2-1-4M2e protein was weaker than the one generated by Flg-HA2-2-4M2e. These recombinant proteins containing both viral peptides provide complete protection from lethal challenge with various influenza viruses: A/H3N2; A/H2N2; and A/H5N1.

Conclusion

This study demonstrates that the intranasal administration of Flg-HA2-2-4M2e recombinant protein induces a strong immune response which provides broad protection against various influenza viruses. This construct is therefore a strong candidate for development as a universal vaccine.

Peptide and protein nanoparticle conjugates: versatile platforms for biomedical applications

Peptide- and protein-nanoparticle conjugates have emerged as powerful tools for biomedical applications, enabling the treatment, diagnosis, and prevention of disease. In this review, we focus on the key roles played by peptides and proteins in improving, controlling, and defining the performance of nanotechnologies. Within this framework, we provide a comprehensive overview of the key sequences and structures utilised to provide biological and physical stability to nano-constructs, direct particles to their target and influence their cellular and tissue distribution, induce and control biological responses, and form polypeptide self-assembled nanoparticles. In doing so, we highlight the great advances made by the field, as well as the challenges still faced in achieving the clinical translation of peptide- and protein-functionalised nano-drug delivery vehicles, imaging species, and active therapeutics.

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.

Gold nanoparticles conjugating recombinant influenza hemagglutinin trimers and flagellin enhanced mucosal cellular immunity

The immunogenicity of subunit vaccines can be augmented by formulating them into nanoparticles. We conjugated recombinant trimetric influenza A/Aichi/2/68(H3N2) hemagglutinin (HA) onto functionalized gold nanoparticle (AuNP) surfaces in a repetitive, oriented configuration. To further improve the immunogenicity, we generated Toll-like receptor 5 (TLR5) agonist flagellin (FliC)-coupled AuNPs as particulate adjuvants. Intranasal immunizations with an AuNP-HA and AuNP-FliC particle mixture elicited strong mucosal and systemic immune responses that protected hosts against lethal influenza challenges. Compared with the AuNP-HA alone group, the addition of AuNP-FliC improved mucosal B cell responses as characterized by elevated influenza specific IgA and IgG levels in nasal, tracheal, and lung washes. AuNP-HA/AuNP-FliC also stimulated antigen-specific interferon-γ (IFN-γ)-secreting CD4⁺ cell proliferation and induced strong effector CD8⁺ T cell activation. Our results indicate that intranasal co-delivery of antigen and adjuvant-displaying AuNPs enhanced vaccine efficacy by inducing potent cellular immune responses.

A growing world of small things: a brief review on the nanostructured vaccines

Vaccines are the most cost-effective intervention in the management of infectious disease. Much of what we perceive as quality of life is related to a good health status and disease absence, for which vaccines are substantially responsible. Nonetheless, there are many infectious diseases for which no vaccine solution is available. That could be due to limitations of the classic approaches to vaccine development, including inactivated, subunit and attenuated vaccines. Nanostructured immunogens belong to a class of nonclassic vaccines in which nanostructures are loaded with antigen-related molecules. Here, we briefly review important features of the nanostructured vaccines – mainly those based in carbon nanotubes and gold nanorods – and discuss their use to prevent infectious diseases, especially those caused by viruses.

Gold nanoparticles as an adjuvant: Influence of size, shape, and technique of combination with CpG on antibody production

Gold nanoparticles (GNPs) are advantageous as an adjuvant in the design of effective vaccines and in the preparation of high-affinity antibodies to haptens and complete antigens. Another method of activating immunocompetent cells with colloidal gold is to conjugate GNPs with CpG oligodeoxynucleotides (ODNs). We examined how the size and shape of GNPs and various combinations of GNPs and CpG ODNs 1826 affect the immune response. When animals were injected with a model antigen (BSA) coupled to gold nanospheres (diameters, 15 and 50nm), nanorods, nanoshells, and nanostars, the titers of the resultant antibodies differed substantially. The antibody titers decreased in the sequence GNPs-50nm>GNPs-15nm>nanoshells>nanostars>nanorods>native BSA. We conclude that 50 and 15nm gold nanospheres are the optimal antigen carrier and adjuvant for immunization. The highest titer of anti-BSA antibodies was detected in the blood serum of mice immunized simultaneously with BSA-GNP and CpG-GNP conjugates.

Characterization and Molecular Mechanism of Peptide-Conjugated Gold Nanoparticle Inhibiting p53-HDM2 Interaction in Retinoblastoma

Inhibition of the interaction between p53 and HDM2 is an effective therapeutic strategy in cancers that harbor a wild-type p53 protein such as retinoblastoma (RB). Nanoparticle-based delivery of therapeutic molecules has been shown to be advantageous in localized delivery, including to the eye, by overcoming ocular barriers. In this study, we utilized biocompatible gold nanoparticles (GNPs) to deliver anti-HDM2 peptide to RB cells. Characterization studies suggested that GNP-HDM2 was stable in biologically relevant solvents and had optimal cellular internalization capability, the primary requirement of any therapeutic molecule. GNP-HDM2 treatment in RB cells in vitro suggested that they function by arresting RB cells at the G2M phase of the cell cycle and initiating apoptosis. Analysis of molecular changes in GNP-HDM2-treated cells by qRT-PCR and western blotting revealed that the p53 protein was upregulated; however, transactivation of its downstream targets was minimal, except for the PUMA-BCl2 and Bax axis. Global gene expression and in silico bioinformatic analysis of GNP-HDM2-treated cells suggested that upregulation of p53 might presumptively mediate apoptosis through the induction of p53-inducible miRNAs.

Nanoparticle orientationally displayed antigen epitopes improve neutralizing antibody level in a model of porcine circovirus type 2

Recent advancements in biotechnology have enabled the rapid identification and subsequent expression of pathogenic microbial major antigens that induce protective immune responses. However, subunit vaccines have not been successfully commercialized mainly due to the lack of sufficient levels of neutralizing antibodies (NAs). High levels of NA rely on the efficient recognition and cross-linking of multiple neutralizing epitopes with B-cell receptors (BCRs). Nanoparticles are able to display coupled antigenic arrays at high density and provide multiple binding molecular scenarios with BCRs. The high-resolution antigenic structure makes it possible to accurately display stable neutralizing epitopes. Therefore, the development of a nanovaccine that orientationally displays neutralizing epitopes is a feasible strategy. To address this hypothesis, the capsid (Cap) protein of porcine circovirus type 2 as model antigen was conjugated to gold nanoparticles (AuNPs) through direct reaction of the mercapto group of the unique cysteines with AuNPs, rendering Cap-AuNPs to have neutralizing epitopes on outer surface and an immunodominant epitope buried within the inner surface. In vitro studies showed that AuNPs promoted the phagocytosis of Cap protein and NA levels were significantly improved, meanwhile antibody levels against the immunodominant epitope was significantly reduced. In mouse studies, Cap-AuNP-immunized mice displayed a high production of interleukin (IL)-4, IL-10, and interferon-γ, suggesting that Cap-AuNPs can effectively activate CD4⁺ and CD8⁺ T cells and balance Th1 and Th2 cellular responses. This study presents a new vaccine design strategy based on antigen structure, where nanoparticles are coupled to antigens in well-ordered arrays and orientationally display neutralizing epitopes to enhance NA levels.

Dual-linker gold nanoparticles as adjuvanting carriers for multivalent display of recombinant influenza hemagglutinin trimers and flagellin improve the immunological responses in vivo and in vitro

Vaccination is the most cost-effective means of infectious disease control. Although current influenza vaccines are effective in battling closely matched strains, such vaccines have major limitations such as the requirement to produce new vaccines every season, an egg-dependent production system, long production periods, uncertainty in matching the vaccine to circulating strains, and the inability to react to new influenza pandemics resulting from genetic drift or shift. To overcome the intrinsic limitations of the conventional influenza vaccine, we have designed dual-linker gold nanoparticles (AuNPs) conjugated with both recombinant trimetric A/Aichi/2/68 (H3N2), hemagglutinin (HA) and TLR5 agonist flagellin (FliC) as a novel vaccine approach. Click chemistry and metal-chelating reactions were used to couple the two proteins. The conjugated proteins were found to possess high coupling specificity, high stability in harsh environments, high conjugation efficiency, and the ability to keep the appropriate protein conformations for immunogenicity and immunostimulation. Both AuNPs-HA/FliC and AuNPs-HA formulations induced higher levels of antibody responses than a mixture of soluble HA and FliC proteins when administered via a single intranasal immunization in mice. To further investigate the adjuvancy of these nanoparticles, in vitro experiments were conducted in both the JAWS II dendritic cell (DC) line and bone marrow-derived DC (BMDC) models. The results showed that dual-conjugated AuNPs were rapidly targeted and taken up by DCs. Consequently, DCs were induced toward maturation, as demonstrated by high levels of cytokine secretions and membrane costimulatory molecule expression. T cell proliferation was observed when splenic T cells were cocultured with AuNPs-HA/FliC-primed BMDCs. These results suggest that dual-conjugated AuNPs are effective at simultaneously displaying antigens and adjuvants in an oriented, multivalent format and can promote a strong immune response by activating DCs and T cells.

The role of nanotechnology in the treatment of viral infections

Infectious diseases are the leading cause of mortality worldwide, with viruses in particular making global impact on healthcare and socioeconomic development. In addition, the rapid development of drug resistance to currently available therapies and adverse side effects due to prolonged use is a serious public health concern. The development of novel treatment strategies is therefore required. The interaction of nanostructures with microorganisms is fast-revolutionizing the biomedical field by offering advantages in both diagnostic and therapeutic applications. Nanoparticles offer unique physical properties that have associated benefits for drug delivery. These are predominantly due to the particle size (which affects bioavailability and circulation time), large surface area to volume ratio (enhanced solubility compared to larger particles), tunable surface charge of the particle with the possibility of encapsulation, and large drug payloads that can be accommodated. These properties, which are unlike bulk materials of the same compositions, make nanoparticulate drug delivery systems ideal candidates to explore in order to achieve and/or improve therapeutic effects. This review presents a broad overview of the application of nanosized materials for the treatment of common viral infections.

Nanoparticle Vaccines Adopting Virus-like Features for Enhanced Immune Potentiation

Synthetic nanoparticles play an increasingly significant role in vaccine design and development as many nanoparticle vaccines show improved safety and efficacy over conventional formulations. These nanoformulations are structurally similar to viruses, which are nanoscale pathogenic organisms that have served as a key selective pressure driving the evolution of our immune system. As a result, mechanisms behind the benefits of nanoparticle vaccines can often find analogue to the interaction dynamics between the immune system and viruses. This review covers the advances in vaccine nanotechnology with a perspective on the advantages of virus mimicry towards immune potentiation. It provides an overview to the different types of nanomaterials utilized for nanoparticle vaccine development, including functionalization strategies that bestow nanoparticles with virus-like features. As understanding of human immunity and vaccine mechanisms continue to evolve, recognizing the fundamental semblance between synthetic nanoparticles and viruses may offer an explanation for the superiority of nanoparticle vaccines over conventional vaccines and may spur new design rationales for future vaccine research. These nanoformulations are poised to provide solutions towards pressing and emerging human diseases.

Applications of Gold Nanoparticles in Nanomedicine: Recent Advances in Vaccines

Nowadays, gold is used in (nano-)medicine, usually in the form of nanoparticles, due to the solid proofs given of its therapeutic effects on several diseases. Gold also plays an important role in the vaccine field as an adjuvant and a carrier, reducing toxicity, enhancing immunogenic activity, and providing stability in storage. An even brighter golden future is expected for gold applications in this area.

Consensus M2e peptide conjugated to gold nanoparticles confers protection against H1N1, H3N2 and H5N1 influenza A viruses

The extracellular domain of influenza A ion channel membrane matrix protein 2 (M2e) is considered to be a potential candidate to develop a universal influenza A vaccine. However poor immunogenicity of M2e presents a significant roadblock. We have developed a vaccine formulation comprising of the consensus M2e peptide conjugated to gold nanoparticles (AuNPs) with CpG as a soluble adjuvant (AuNP-M2e + sCpG). We demonstrate that intranasal delivery of AuNP-M2e + sCpG in mice induces lung B cell activation and robust serum anti-M2e immunoglobulin G (IgG) response, with stimulation of both IgG1 and IgG2a subtypes. Using Madin-Darby canine kidney (MDCK) cells infected with A/California/04/2009 (H1N1pdm) pandemic strain, or A/Victoria/3/75 (H3N2), or the highly pathogenic avian influenza virus A/Vietnam/1203/2004 (H5N1) as immunosorbants we further show that the antibodies generated are also capable of binding to the homotetrameric form of M2 expressed on infected cells. Lethal challenge of vaccinated mice with A/California/04/2009 (H1N1pdm) pandemic strain, A/Victoria/3/75 (H3N2), and the highly pathogenic avian influenza virus A/Vietnam/1203/2004 (H5N1) led to 100%, 92%, and 100% protection, respectively. Overall, this study helps to lay the foundation of a potential universal influenza A vaccine.

Role of Metallic Nanoparticles in Vaccinology: Implications for Infectious Disease Vaccine Development

Subunit vaccines are safer but less immunogenic than live-attenuated vaccines or whole cell inactivated vaccines. Adjuvants are used to enhance and modulate antigen (Ag) immunogenicity, aiming to induce a protective and long-lasting immune response. Several molecules and formulations have been studied for their adjuvanticity, but only seven have been approved to formulate human vaccines. Metallic nanoparticles (MeNPs), particularly those containing gold and iron oxides, are widely used in medicine for diagnosis and therapy and have been used as carriers for drugs and vaccines. However, little is known about the immune response elicited by MeNPs or about their importance in the development of new vaccines. There is evidence that these particles display adjuvant characteristics, promoting cell recruitment, antigen-presenting cell activation, cytokine production, and inducing a humoral immune response. This review focuses on the characteristics of MeNPs that could facilitate the induction of a cellular immune response, particularly T-helper 1 and T-helper 17, and their potential functions as adjuvants for subunit vaccines.

Immunological properties of gold nanoparticles

In the past decade, gold nanoparticles have attracted strong interest from the nanobiotechnological community owing to the significant progress made in robust and easy-to-make synthesis technologies, in surface functionalization, and in promising biomedical applications. These include bioimaging, gene diagnostics, analytical sensing, photothermal treatment of tumors, and targeted delivery of various biomolecular and chemical cargos. For the last-named application, gold nanoparticles should be properly fabricated to deliver the cargo into the targeted cells through effective endocytosis. In this review, we discuss recent progress in understanding the selective penetration of gold nanoparticles into immune cells. The interaction of gold nanoparticles with immune cell receptors is discussed. As distinct from other published reviews, we present a summary of the immunological properties of gold nanoparticles. This review also summarizes what is known about the application of gold nanoparticles as an antigen carrier and adjuvant in immunization for the preparation of antibodies in vivo. For each of the above topics, the basic principles, recent advances, and current challenges are discussed. Thus, this review presents a detailed analysis of data on interaction of gold nanoparticles with immune cells. Emphasis is placed on the systematization of data over production of antibodies by using gold nanoparticles and adjuvant properties of gold nanoparticles. Specifically, we start our discussion with current data on interaction of various gold nanoparticles with immune cells. The next section describes existing technologies to improve production of antibodies in vivo by using gold nanoparticles conjugated with specific ligands. Finally, we describe what is known about adjuvant properties of bare gold or functionalized nanoparticles. In the Conclusion section, we present a short summary of reported data and some challenges and perspectives.

Electrically Oscillating Plasmonic Nanoparticles for Enhanced DNA Vaccination against Hepatitis C Virus

The promise of DNA vaccines is far-reaching. However, the development of potent immunization methods remains a key challenge for its use in clinical applications. Here, an approach for in vivo DNA vaccination by electrically activated plasmonic Au nanoparticles is reported. The electrical excitation of plasmonic nanoparticles can drive vibrational and dipole-like oscillations that are able to disrupt nearby cell membranes. In combination with their intrinsic ability to focus and magnify the electric field on the surface of cells, Au nanoparticles allow enhanced cell poration and facilitate the uptake of DNA vaccine. Mice immunized with this approach showed up to 100-fold higher gene expression compared to control treatments (without nanoparticles) and exhibited significantly increased levels of both antibody and cellular immune responses against a model hepatitis C virus DNA vaccine. This approach can be tuned to establish controlled and targeted delivery of different types of therapeutic molecules into cells and live animals as well.

Micro and Nano Material Carriers for Immunomodulation

Modulation of the immune system through the use of micro and nano carriers offers opportunities in transplant tolerance, autoimmunity, infectious disease, and cancer. In particular, polymeric, lipid, and inorganic materials have been used as carriers of proteins, nucleic acids, and small drug molecules to direct the immune system toward either suppressive or stimulatory states. Current technologies have focused on the use of particulates or scaffolds, the modulation of materials properties, and the delivery of biologics or small drug molecules to achieve a desired response. Discussed are relevant immunology concepts, the types of biomaterial carriers used for immunomodulation highlighting their benefits and drawbacks, the material properties influencing immune responses, and recent examples in the field of transplant tolerance.

Mucosal vaccine delivery: Current state and a pediatric perspective

Most childhood infections occur via the mucosal surfaces, however, parenterally delivered vaccines are unable to induce protective immunity at these surfaces. In contrast, delivery of vaccines via the mucosal routes can allow antigens to interact with the mucosa-associated lymphoid tissue (MALT) to induce both mucosal and systemic immunity. The induced mucosal immunity can neutralize the pathogen on the mucosal surface before it can cause infection. In addition to reinforcing the defense at mucosal surfaces, mucosal vaccination is also expected to be needle-free, which can eliminate pain and the fear of vaccination. Thus, mucosal vaccination is highly appealing, especially for the pediatric population. However, vaccine delivery across mucosal surfaces is challenging because of the different barriers that naturally exist at the various mucosal surfaces to keep the pathogens out. There have been significant developments in delivery systems for mucosal vaccination. In this review we provide an introduction to the MALT, highlight barriers to vaccine delivery at different mucosal surfaces, discuss different approaches that have been investigated for vaccine delivery across mucosal surfaces, and conclude with an assessment of perspectives for mucosal vaccination in the context of the pediatric population.

Biomaterials-Based Vaccination Strategies for the Induction of CD8+T Cell Responses

Natural and synthetic biomaterials are increasingly being used for the development of vaccines and immunotherapies as alternatives to traditional live-attenuated formulations due to their improved safety profiles and no risk of reversion to virulence. Polymeric materials in particular enjoy attention due to the ease of fabrication, control over physicochemical properties, and their wide range of immunogenicity. While the majority of studies focus on inducing protective antibody responses, in recent years, materials-based strategies for the delivery of antigens and immunomodulators to improve CD8⁺T cell immunity against infectious and non-infectious diseases have gained momentum. Notably, platforms based on polymeric nanoparticles, liposomes, micelles, virus-like particles, self-assembling peptides and peptidomimetics, and multilayer thin films show considerable promise in preclinical studies. In this Review, we first introduce the concepts of CD8⁺T cell activation, effector and memory functions, and cytotoxic activity, followed by vaccine design for eliciting robust and protective long-lived CD8⁺T cell immunity. We then discuss different materials-based vaccines developed in the past decade to elicit CD8⁺T cell responses based on molecular composition or fabrication methods and conclude with a summary and glimpse at the future trends in this area.

Role of metal and metal oxide nanoparticles as diagnostic and therapeutic tools for highly prevalent viral infections

Nanotechnology is increasingly playing important roles in various fields including virology. The emerging use of metal or metal oxide nanoparticles in virus targeting formulations shows the promise of improved diagnostic or therapeutic ability of the agents while uniquely enhancing the prospects of targeted drug delivery. Although a number of nanoparticles varying in composition, size, shape, and surface properties have been approved for human use, the candidates being tested or approved for clinical diagnosis and treatment of viral infections are relatively less in number. Challenges remain in this domain due to a lack of essential knowledge regarding the in vivo comportment of nanoparticles during viral infections. This review provides a broad overview of recent advances in diagnostic, prophylactic and therapeutic applications of metal and metal oxide nanoparticles in human immunodeficiency virus, hepatitis virus, influenza virus and herpes virus infections. Types of nanoparticles commonly used and their broad applications have been explained in this review.

Gold nanoparticles and their applications in biomedicine

Although used in medical applications for centuries, the development of nanotechnology has shed new light in the plethora of possible medical and biological applications using gold-based nanostructures. Gold nanostructures are stable and relatively inert in biological systems, leading to low reatogenicity, biocompatibility and general lack of toxicity. Allied to that, gold nanoparticles present optical and electronic properties that have been exploited in a range of biomedical applications. In this review we discuss biologically relevant properties of gold nanoparticles and how they are used in some biomedicine fields, especially those involving biosensing of biological analytes – including viruses and antibodies against them, cancer therapies, and antigen delivery, including viral antigens – as part of nonclassic vaccine strategies.

Nanodelivery systems for enhancing the immunostimulatory effect of CpG oligodeoxynucleotides

Synthetic oligodeoxynucleotides containing immunostimulatory CpG motif mimic bacterial DNA and are potent activator of innate and adaptive immune responses. Therefore, CpG ODNs have significant potentials as immunotherapeutic agent for treatment of infectious diseases, allergy and cancer. Many clinical trials involving CpG ODNs either used alone or as adjuvant have been initiated. However, delivery of CpG ODNs to target sites still remains a great challenge due to their extreme susceptibility to nuclease degradation in serum and poor cellular uptake. Chemical modification of CpG ODNs backbone can protect them against degradation by nucleases, but have raised concern regarding several severe side effects. Development of efficient CpG ODNs delivery systems to address these issues and enhance their immunostimulatory effect are highly desirable. In recent years, the emergence of nanotechnology has provided unprecedented opportunities to encapsulate CpG ODN into various nanocarriers or synthesize CpG ODNs nanostructures. This review provides an overview of the delivery systems based on nanomaterials and nanostructures newly developed for enhancing the immunostimulatory effect of CpG ODNs, together with a brief discussion on perspectives for future studies in this field.

Current applications of nanoparticles in infectious diseases

For decades infections have been treated easily with drugs. However, in the 21st century, they may become lethal again owing to the development of antimicrobial resistance. Pathogens can become resistant by means of different mechanisms, such as increasing the time they spend in the intracellular environment, where drugs are unable to reach therapeutic levels. Moreover, drugs are also subject to certain problems that decrease their efficacy. This requires the use of high doses, and frequent administrations must be implemented, causing adverse side effects or toxicity. The use of nanoparticle systems can help to overcome such problems and increase drug efficacy. Accordingly, there is considerable current interest in their use as antimicrobial agents against different pathogens like bacteria, virus, fungi or parasites, multidrug-resistant strains and biofilms; as targeting vectors towards specific tissues; as vaccines and as theranostic systems. This review begins with an overview of the different types and characteristics of nanoparticles used to deliver drugs to the target, followed by a review of current research and clinical trials addressing the use of nanoparticles within the field of infectious diseases.

The potential of nanoparticles for the immunization against viral infections

Vaccination has a great impact on the prevention and control of infectious diseases. However, there are still many infectious diseases for which an effective vaccine is missing. Thirty years after the discovery of the AIDS-pathogen (human immunodeficiency virus, HIV) and intensive research, there is still no protective immunity against the HIV infection. Over the past decade, nanoparticulate systems such as virus-like particles, liposomes, polymers and inorganic nanoparticles have received attention as potential delivery vehicles which can be loaded or functionalized with active biomolecules (antigens and adjuvants). Here we compare the properties of different nanoparticulate systems and assess their potential for the development of new vaccines against a range of viral infections.

Nasal and pulmonary vaccine delivery using particulate carriers

INTRODUCTION

Many human pathogens cause respiratory illness by colonizing and invading the respiratory mucosal surfaces. Preventing infection at local sites via mucosally active vaccines is a promising and rational approach for vaccine development. However, stimulating mucosal immunity is often challenging. Particulate adjuvants that can specifically target mucosal immune cells offer a promising opportunity to stimulate local immunity at the nasal and/or pulmonary mucosal surfaces.

AREAS COVERED

This review analyzes the common causes of respiratory infections, the challenges in the induction of mucosal and systemic responses and current pulmonary and nasal mucosal vaccination strategies. The ability of various particulate adjuvant formulations, including lipid-based particles, polymers and other particulate systems, to be effectively utilized for mucosal vaccine delivery is discussed.

EXPERT OPINION

Induction of antibody and cell-mediated mucosal immunity that can effectively combat respiratory pathogens remains a challenge. Particulate delivery systems can be developed to target mucosal immune cells and effectively present antigen to evoke a rapid and long-term local immunity in the respiratory mucosa. In particular, particulate delivery systems offer the versatility of being formulated with multiple adjuvants and antigenic cargo, and can be tailored to effectively prime immune responses across the mucosal barrier. The opportunity for rational design of novel subunit particulate vaccines is emerging.

Intranasal and oral vaccination with protein-based antigens: advantages, challenges and formulation strategies

Most pathogens initiate their infections at the human mucosal surface. Therefore, mucosal vaccination, especially through oral or intranasal administration routes, is highly desired for infectious diseases. Meanwhile, protein-based antigens provide a safer alternative to the whole pathogen or DNA based ones in vaccine development. However, the unique biopharmaceutical hurdles that intranasally or orally delivered protein vaccines need to overcome before they reach the sites of targeting, the relatively low immunogenicity, as well as the low stability of the protein antigens, require thoughtful and fine-tuned mucosal vaccine formulations, including the selection of immunostimulants, the identification of the suitable vaccine delivery system, and the determination of the exact composition and manufacturing conditions. This review aims to provide an up-to-date survey of the protein antigen-based vaccine formulation development, including the usage of immunostimulants and the optimization of vaccine delivery systems for intranasal and oral administrations.

Particulate inorganic adjuvants: recent developments and future outlook

Objectives

To review the state of the art and assess future potential in the use of inorganic particulates as vaccine adjuvants.

Key findings

An adjuvant is an entity added to a vaccine formulation to ensure that robust immunity to the antigen is inculcated. The inclusion of an adjuvant is typically vital for the efficacy of vaccines using inactivated organisms, subunit and DNA antigens. With increasing research efforts being focused on subunit and DNA antigens because of their improved safety profiles, the development of appropriate adjuvants is becoming ever more crucial. Despite this, very few adjuvants are licensed for use in humans (four by the FDA, five by the European Medicines Agency). The most widely used adjuvant, alum, has been used for nearly 90 years, yet its mechanism of action remains poorly understood. In addition, while alum produces a powerful antibody Th2 response, it does not provoke the cellular immune response required for the elimination of intracellular infections or cancers. New adjuvants are therefore needed, and inorganic systems have attracted much attention in this regard.

Summary

In this review, the inorganic adjuvants currently in use are considered, and the efforts made to date to understand their mechanisms of action are summarised. We then move on to survey the literature on inorganic particulate adjuvants, focusing on the most interesting recent developments in this area and their future potential.

Oral delivery of nanoparticle-based vaccines

Most infectious diseases are caused by pathogenic infiltrations from the mucosal tract. Therefore, vaccines delivered to the mucosal tissues can mimic natural infections and provide protection at the first site of infection. Thus, mucosal, especially, oral delivery is becoming the most preferred mode of vaccination. However, oral vaccines have to overcome several barriers such as the extremely low pH of the stomach, the presence of proteolytic enzymes and bile salts as well as low permeability in the intestine. Several formulations based on nanoparticle strategies are currently being explored to prepare stable oral vaccine formulations. This review briefly discusses several molecular mechanisms involved in intestinal immune cell activation and various aspects of oral nanoparticle-based vaccine design that should be considered for improved mucosal and systemic immune responses.

Synthesis and Immunogenicity Assessment of Elastin-Like Polypeptide-M2e Construct as an Influenza Antigen

The 23 amino acid-long extracellular domain of the influenza virus transmembrane protein M2 (M2e) has remained highly conserved since the 1918 pandemic, and is thus considered a good candidate for development of a universal influenza A vaccine. However, M2e is poorly immunogenic. In this study we assessed the potential of increasing immunogenicity of M2e by constructing a nanoscale-designed protein polymer containing the M2e sequence and an elastin-like polypeptide (ELP) nanodomain consisting of alanine and tyrosine guest residues (ELP(A₂YA₂)₂₄). The ELP nanodomain was included to increase antigen size, and to exploit the inherent thermal inverse phase transition behavior of ELPs to purify the protein polymer. The ELP(A₂YA₂)₂₄ + M2e nanodomained molecule was recombinantly synthesized. Characterization of its inverse phase transition behavior demonstrated that attachment of M2e to ELP(A₂YA₂)₂₄ increased its transition temperature compared to ELP(A₂YA₂)₂₄. Using a dot blot test we determined that M2e conjugated to ELP is recognizable by M2e-specific antibodies, suggesting that the conjugation process does not adversely affect the immunogenic property of M2e. Further, upon vaccinating mice with ELP(A₂YA₂)₂₄ + M2e it was found that indeed the nanodomained protein enhanced M2e-specific antibodies in mouse serum compared to free M2e peptide and ELP(A₂YA₂)₂₄. The immune serum could also recognize M2 expressed on influenza virions. Overall, this data suggests the potential of using molecules containing M2e-ELP nano-domains to develop a universal influenza vaccine.

Intranasal formulations: promising strategy to deliver vaccines

INTRODUCTION

The emergence of new diseases and the lack of efficient vaccines against numerous non-treatable pathogens require the development of novel vaccination strategies. To date, only a few mucosal vaccines have been approved for humans. This was in part due to i) the use of live attenuated vaccines, which are not suitable for certain groups of individuals, ii) safety concerns derived from implementation in humans of some mucosal vaccines, iii) the poor stability, absorption and immunogenicity of antigens delivered by the mucosal route and iv) the limited number of available technologies to overcome the bottlenecks associated with mucosal antigen delivery. Recent advances make feasible the development of efficacious mucosal vaccines with adequate safety profile. Thus, currently intranasal vaccines represent an attractive and valid alternative to conventional vaccines.

AREAS COVERED

The present review is focused on the potentials and limitations of market-approved intranasal vaccines and promising candidates undergoing clinical investigations. Furthermore, emerging strategies to overcome main bottlenecks including efficient breaching of the mucosal barrier and safety concerns by implementation of new adjuvants and delivery systems are discussed.

EXPERT OPINION

The rational design of intranasal vaccines requires an in-depth understanding of the anatomic, physicochemical and barrier properties of the nasal mucosa, as well as the molecular mechanisms governing the activation of the local innate and adaptive immune system. This would provide the critical knowledge to establish effective approaches to deliver vaccine antigens across the mucosal barrier, supporting the stimulation of a long-lasting protective response at both mucosal and systemic levels. Current developments in the area of adjuvants, nanotechnologies and mucosal immunology, together with the identification of surface receptors that can be exploited for cell targeting and manipulating their physiological properties, will become instrumental for developing a new generation of more effective intranasal vaccines.

Universal influenza vaccines, a dream to be realized soon

Due to frequent viral antigenic change, current influenza vaccines need to be re-formulated annually to match the circulating strains for battling seasonal influenza epidemics. These vaccines are also ineffective in preventing occasional outbreaks of new influenza pandemic viruses. All these challenges call for the development of universal influenza vaccines capable of conferring broad cross-protection against multiple subtypes of influenza A viruses. Facilitated by the advancement in modern molecular biology, delicate antigen design becomes one of the most effective factors for fulfilling such goals. Conserved epitopes residing in virus surface proteins including influenza matrix protein 2 and the stalk domain of the hemagglutinin draw general interest for improved antigen design. The present review summarizes the recent progress in such endeavors and also covers the encouraging progress in integrated antigen/adjuvant delivery and controlled release technology that facilitate the development of an affordable universal influenza vaccine.