Pre-clinical evaluation of a novel nanoemulsion-based hepatitis B mucosal vaccine

Formulation and characterization of nanoemulsion intranasal adjuvants: effects of surfactant composition on mucoadhesion and immunogenicity

The development of effective intranasal vaccines is of great interest due to their potential to induce both mucosal and systemic immunity. Here we produced oil-in-water nanoemulsion (NE) formulations containing various cationic and nonionic surfactants for use as adjuvants for the intranasal delivery of vaccine antigens. NE induced immunogenicity and antigen delivery are believed to be facilitated through initial contact interactions between the NE droplet and mucosal surfaces which promote prolonged residence of the vaccine at the site of application, and thus cellular uptake. However, the details of this mechanism have yet to be fully characterized experimentally. We have studied the physicochemical properties of the NE droplet surfactant components and demonstrate that properties such as charge and polar headgroup geometry influence the association of the adjuvant with the mucus protein, mucin. Association of NE droplets with mucin in vitro was characterized by various biophysical and imaging methods including dynamic light scattering (DLS), zeta potential (ZP), and surface plasmon resonance (SPR) measurements as well as transmission electron microscopy (TEM). Emulsion surfactant compositions were varied in a systematic manner to evaluate the effects of hydrophobicity and polar group charge/size on the NE-mucin interaction. Several cationic NE formulations were found to facilitate cellular uptake of the model antigen, ovalbumin (OVA), in a nasal epithelial cell line. Furthermore, fluorescent images of tissue sections from mice intranasally immunized with the same NEs containing green fluorescent protein (GFP) antigen demonstrated that these NEs also enhanced mucosal layer penetration and cellular uptake of antigen in vivo. NE-mucin interactions observed through biophysical measurements corresponded with the ability of the NE to enhance cellular uptake. Formulations that enhanced antigen uptake in vitro and in vivo also led to the induction of a more consistent antigen specific immune response in mice immunized with NEs containing OVA, linking NE-facilitated mucosal layer penetration and cellular uptake to enhancement of the immune response. These findings suggest that biophysical measurement of the mucoadhesive properties of emulsion based vaccines constitutes an effective in vitro strategy for selecting NE candidates for further evaluation in vivo as mucosal adjuvants.

Intranasal immunization with W 80 5EC adjuvanted recombinant RSV rF-ptn enhances clearance of respiratory syncytial virus in a mouse model

Respiratory Syncytial Virus (RSV) is a ubiquitous virus that infects almost all people by age two and is a major source of respiratory illness in infants, the elderly and others with compromised immune systems. Currently there is no available vaccine. Prior efforts using formalin-inactivated RSV (FI-RSV) were associated with enhanced respiratory disease upon viral exposure following clinical vaccine trials. Several researchers and pharmaceutical companies have utilized vector-associated live attenuated RSV vaccines in pre-clinical and clinical studies. Another attractive approach, however, is a subunit vaccine which would be easier to produce and quality control. Our group has previously demonstrated in a murine model of infection that intranasal immunization with nanoemulsion-inactivated and adjuvanted RSV induces humoral and cellular immune responses, resulting in protection against RSV infection. The present studies characterize the immune responses elicited by intranasal RSV F protein adjuvanted with nanoemulsion. Intranasal application of nanoemulsion adjuvanted F protein induced a rapid and robust systemic and mucosal antibody response, as well as protection against subsequent RSV challenge. Importantly, RSV challenge in immunized animals did not elicit airway hyper-reactivity, a Th2-skewed immune response or immunopathology associated with hypersensitivity reactions with formalin-inactivated vaccine. These results suggest that RSV F protein adjuvanted with nanoemulsion may be a good mucosal vaccine candidate. Formulating RSV F protein in nanoemulsion creates a well-defined and well-controlled vaccine that can be delivered intranasally to induce T cell mediated immunity without inducing enhanced disease associated with the mouse model of FI-RSV vaccination and infection.

Receptor-specific delivery of protein antigen to dendritic cells by a nanoemulsion formed using top-down non-covalent click self-assembly

A new class of targeted and immune-evading nanocarrier made using only biological components and facile processes is assembled in a bottom-up fashion. Simple top-down sequential addition of immune-evading or receptor-specific antibody elements conjugated to biosurfactant protein DAMP4 promotes self-assembly at an interface previously formed in the presence of peptide surfactant AM1, leading to a functional display at the interface through non-covalent molecular self-assembly.

Applications of nanotechnology for immunology

Nanotechnology uses the unique properties of objects that function as a unit within the overall size range of 1-1,000 nanometres. The engineering of nanostructure materials, including nanoparticles, nanoemulsions or nanotubules, holds great promise for the development of new immunomodulatory agents, as such nanostructures can be used to more effectively manipulate or deliver immunologically active components to target sites. Successful applications of nanotechnology in the field of immunology will enable new generations of vaccines, adjuvants and immunomodulatory drugs that aim to improve clinical outcomes in response to a range of infectious and non-infectious diseases.

Nanoparticle vaccines encompassing the respiratory syncytial virus (RSV) G protein CX3C chemokine motif induce robust immunity protecting from challenge and disease

Nanoparticle vaccines were produced using layer-by-layer fabrication and incorporating respiratory syncytial virus (RSV) G protein polypeptides comprising the CX3C chemokine motif. BALB/c mice immunized with G protein nanoparticle vaccines produced a neutralizing antibody response that inhibited RSV replication in the lungs following RSV challenge. ELISPOT analysis showed that G nanoparticle vaccinated mice had increased levels of RSV G protein-specific IL-4 and IFN-γ secreting cells compared to controls following RSV challenge. Remarkably, RSV challenge of G protein nanoparticle vaccinated mice resulted in increased RSV M2-specific IL-4 and IFN-γ secreting T cells, and increased M2-specific H-2Kd-tetramer positive CD8⁺ T cells in the lungs compared to controls. Cell type analysis showed vaccination was not associated with increased pulmonary eosinophilia following RSV challenge. These results demonstrate that vaccination of mice with the RSV G protein nanoparticle vaccines induces a potent neutralizing antibody response, increased G protein- and M2- specific T cell responses, and a reduction in RSV disease pathogenesis.

Fourth International Conference: Modern Vaccines/Adjuvants Formulation--Impact on Future Development: May 15-17 2013, CHUV, Lausanne, Switzerland

On the 15-17th of May 2013, about 120 scientists, postdoctoral fellows and professors representing renowned academic institutes and senior scientists and executives from small biotechs, contract research organizations (CROs) and Big Pharma companies, gathered at the Centre Hospitalier Universitaire Vaudois (CHUV) in Lausanne, Switzerland for the 4th international conference on Modern Vaccines and Adjuvants Formulation. Despite this relative small number, the speakers and attendees covered together a very broad field of expertise. Indeed, experts in microbiology, immunology, biochemistry, formulation, virus and nanoparticle characterization, vaccine production, quality control as well as regulatory professionals attended the conference and were able to present their works and discuss new developments within the field of vaccine and adjuvant development, characterization and approval process. This broad diversity was a highpoint of the conference and allowed for a stimulating environment and underlined the complexity of the challenges that the field currently faces in order to develop better or completely new vaccines and adjuvants.

Nanotechnological Approaches for Genetic Immunization

Genetic immunization is one of the important findings that provide multifaceted immunological response against infectious diseases. With the advent of r-DNA technology, it is possible to construct vector with immunologically active genes against specific pathogens. Nevertheless, site-specific delivery of constructed genetic material is an important contributory factor for eliciting specific cellular and humoral immune response. Nanotechnology has demonstrated immense potential for the site-specific delivery of biomolecules. Several polymeric and lipidic nanocarriers have been utilized for the delivery of genetic materials. These systems seem to have better compatibility, low toxicity, economical and capable to delivering biomolecules to intracellular site for the better expression of desired antigens. Further, surface engineering of nanocarriers and targeting approaches have an ability to offer better presentation of antigenic material to immunological cells. This chapter gives an overview of existing and emerging nanotechnological approaches for the delivery of genetic materials.

Plasmodium falciparum synthetic LbL microparticle vaccine elicits protective neutralizing antibody and parasite-specific cellular immune responses

Epitopes of the circumsporozoite (CS) protein of Plasmodium falciparum, the most pathogenic species of the malaria parasite, have been shown to elicit protective immunity in experimental animals and human volunteers. The mechanisms of immunity include parasite-neutralizing antibodies that can inhibit parasite motility in the skin at the site of infection and in the bloodstream during transit to the hepatocyte host cell and also block interaction with host cell receptors on hepatocytes. In addition, specific CD4+ and CD8+ cellular mechanisms target the intracellular hepatic forms, thus preventing release of erythrocytic stage parasites from the infected hepatocyte and the ensuing blood stage cycle responsible for clinical disease. An innovative method for producing particle vaccines, layer-by-layer (LbL) fabrication of polypeptide films on solid CaCO3 cores, was used to produce synthetic malaria vaccines containing a tri-epitope CS peptide T1BT comprising the antibody epitope of the CS repeat region (B) and two T-cell epitopes, the highly conserved T1 epitope and the universal epitope T. Mice immunized with microparticles loaded with T1BT peptide developed parasite-neutralizing antibodies and malaria-specific T-cell responses including cytotoxic effector T-cells. Protection from liver stage infection following challenge with live sporozoites from infected mosquitoes correlated with neutralizing antibody levels. Although some immunized mice with low or undetectable neutralizing antibodies were also protected, depletion of T-cells prior to challenge resulted in the majority of mice remaining resistant to challenge. In addition, mice immunized with microparticles bearing only T-cell epitopes were not protected, demonstrating that cellular immunity alone was not sufficient for protective immunity. Although the microparticles without adjuvant were immunogenic and protective, a simple modification with the lipopeptide TLR2 agonist Pam3Cys increased the potency and efficacy of the LbL vaccine candidate. This study demonstrates the potential of LbL particles as promising malaria vaccine candidates using the T1BT epitopes from the P. falciparum CS protein.

Nanovaccines : nanocarriers for antigen delivery

Vaccination has become one of the most important health interventions of our times, revolutionizing health care, and improving the quality of life and life expectancy of millions all over the world. In spite of this, vaccine research remains a vast field for innovation and improvement. Indeed, the shift towards the use of sub-unit antigens, much safer but less immunogenic, and the recognized need to facilitate the access to vaccines in the global framework is currently stimulating the search for safe and efficient adjuvants and delivery technologies. Within this context, nanocarriers have gained particular attention over the last years and appear as one of the most promising strategies for antigen delivery. A number of biomaterials and technologies can be used to design nanovaccines that fulfill the requirements of new vaccination approaches, such as single-dose and transmucosal immunization, critical for achieving a widespread coverage while reducing the overall costs in relation to traditional forms of vaccination. Here we present an overview of the current state of nanocarriers for antigen delivery, developed with the perspective of contributing to the global vaccination goal.

Nanoemulsion nasal adjuvant W₈₀5EC induces dendritic cell engulfment of antigen-primed epithelial cells

Nanoemulsions are adjuvants that enhance antigen penetration in the nasal mucosa, increase cellular uptake of antigens by both epithelial dendritic cells, and promote migration of antigen-loaded dendritic cells to regional lymph nodes within a day of vaccine administration. The objective of this study was to determine whether the W(80)5EC nanoemulsion adjuvant enhances immune response not only by direct uptake of antigen by dendritic cells, but also indirectly, by phagocytosis of antigen-primed, apoptotic, epithelial cells. Consistent with this, we show that exposure of both epithelial cells (TC-1s) and dendritic cells (JAWS II or bone marrow derived dendritic cells (BMDCs)) to nanoemulsion exhibited augmented antigen uptake in cell culture. TC-1 cells subsequently underwent G(2)/M cell cycle arrest and apoptosis, and when co-cultured with JAWS II or BMDCs were rapidly engulfed by the dendritic cells, which responded by up-regulating dendritic cell maturation marker CD86. Altogether these results suggest that the effectiveness of nanoemulsions as adjuvants stems, at least in part, from the engulfment of antigen-loaded epithelial cells, leading to enhanced antigen processing and a strong and balanced mucosal and systemic immune response.

Characterization and immunogenicity of norovirus capsid-derived virus-like particles purified by anion exchange chromatography

Recombinant baculovirus (BV) expression systems are widely applied in the production of viral capsid proteins and virus-like particles (VLPs) for use as immunogens and vaccine candidates. Traditional density gradient purification of VLPs does not enable complete elimination of BV-derived impurities, including live viruses, envelope glycoprotein gp64 and baculoviral DNA. We used an additional purification system based on ionic strength to purify norovirus (NoV) GII-4 capsid-derived VLPs. The anion exchange chromatography purification led to highly purified VLPs free from BV impurities with intact morphology. In addition, highly purified VLPs induced strong NoV-specific antibody responses in BALB/c mice. Here, we describe a method for NoV VLP purification and several methods for determining their purity, including quantitative PCR for BV DNA detection.

Nanoemulsion W805EC improves immune responses upon intranasal delivery of an inactivated pandemic H1N1 influenza vaccine

Currently available influenza vaccines provide suboptimal protection. In order to improve the quality of protective immune responses elicited following vaccination, we developed an oil-in-water nanoemulsion (NE)-based adjuvant for an intranasally-delivered inactivated influenza vaccine. Using a prime-boost vaccination regimen, we show that intranasal vaccines containing the W(80)5EC NE elicited higher titers of serum hemagglutination inhibiting (HAI) antibody and influenza-specific IgG and IgA titers compared to vaccines that did not contain the NE. Similarly, vaccines containing the W(80)5EC NE resulted in higher influenza-specific IgA levels in the bronchoalveolar lavage (BAL) fluid and nasal wash when compared to vaccines formulated without NE. The higher antibody titers in mice immunized with the NE-containing vaccines correlated with reduced viral loads in the lungs and nasal turbinates following a high dose viral challenge. Mice immunized with vaccines containing the W(80)5EC NE also showed a reduction in body weight loss following challenge compared to mice immunized with equivalent vaccines produced without NE. Taken together, our results show that the W(80)5EC NE substantially improves the magnitude of protective influenza-specific antibody responses and is a promising mucosal adjuvant for influenza vaccines and vaccines against other mucosal pathogens.

Multivalent porous silicon nanoparticles enhance the immune activation potency of agonistic CD40 antibody

One of the fundamental paradigms in the use of nanoparticles to treat disease is to evade or suppress the immune system in order to minimize systemic side effects and deliver sufficient nanoparticle quantities to the intended tissues. However, the immune system is the body's most important and effective defense against diseases. It protects the host by identifying and eliminating foreign pathogens as well as self-malignancies. Here we report a nanoparticle engineered to work with the immune system, enhancing the intended activation of antigen presenting cells (APCs). We show that luminescent porous silicon nanoparticles (LPSiNPs), each containing multiple copies of an agonistic antibody (FGK45) to the APC receptor CD40, greatly enhance activation of B cells. The cellular response to the nanoparticle-based stimulators is equivalent to a 30-40 fold larger concentration of free FGK45. The intrinsic near-infrared photoluminescence of LPSiNPs is used to monitor degradation and track the nanoparticles inside APCs.

Nanoemulsion mucosal adjuvant uniquely activates cytokine production by nasal ciliated epithelium and induces dendritic cell trafficking

While the nasal mucosa is a potentially useful site for human immunization, toxin-based nasal adjuvants are generally unsafe and less effective in humans. Safe mucosal adjuvants that activate protective immunity via mucosal administration are highly dependent on barrier antigen sampling by epithelial and DCs. Here, we demonstrate that protein antigens formulated in unique oil-in-water nanoemulsions (NEs) result in distinctive transcellular antigen uptake in ciliated nasal epithelial cells, leading to delivery into nasal associated lymphoid tissue. NE formulation also enhances MHC class II expression in epithelial cells and DC activation/trafficking to regional lymphoid tissues in mice. These materials appear to induce local epithelial cell apoptosis and heterogeneous cytokine production by mucosal epithelial cells and mixed nasal tissues, including G-CSF, GM-CSF, IL-1a, IL-1b, IL-5, IL-6, IL-12, IP-10, KC, MIP-1a, TGF-β, and TSLP. This is the first observation of a nasal adjuvant that activates calreticulin-associated apoptosis of ciliated nasal epithelial cells to generate broad cytokine/chemokine responses in mucosal tissue.

Mucosal vaccine design and delivery

Mucosal surfaces are a major portal of entry for many human pathogens that are the cause of infectious diseases worldwide. Vaccines capable of eliciting mucosal immune responses can fortify defenses at mucosal front lines and protect against infection. However, most licensed vaccines are administered parenterally and fail to elicit protective mucosal immunity. Immunization by mucosal routes may be more effective at inducing protective immunity against mucosal pathogens at their sites of entry. Recent advances in our understanding of mucosal immunity and identification of correlates of protective immunity against specific mucosal pathogens have renewed interest in the development of mucosal vaccines. Efforts have focused on efficient delivery of vaccine antigens to mucosal sites that facilitate uptake by local antigen-presenting cells to generate protective mucosal immune responses. Discovery of safe and effective mucosal adjuvants are also being sought to enhance the magnitude and quality of the protective immune response.

Induction of immune tolerance in mice with a novel mucosal nanoemulsion adjuvant and self-antigen

AIM

The aim of this study was to investigate the impact of a novel nanoemulsion (NE) adjuvant, a soybean oil emulsion, on autoimmune response. To this end, we used murine thyroglobulin (mTg)-induced experimental autoimmune thyroiditis in mice as a study model.

MATERIALS & METHODS

Mice received NE or NE + mTg by nasal delivery. At 1 week after the second nasal delivery of NE with or without mTg, all mice were immunized with mTg and lipopolysaccharides to induce experimental autoimmune thyroiditis.

RESULTS

Compared with controls, mTg-NE-treated mice had much more antigens accumulated in the nasal passage and thymus and developed a milder form of thyroiditis. This was accompanied by an increase in IL-10, IL-17 and reduced IFN-γ. The production of anti-mTg antibodies was significantly decreased in mTg-NE-treated mice. The percentage of Tregs in cervical lymph nodes was higher in mTg-NE-treated mice than NE-treated mice. Furthermore, Foxp3 and TGF-β levels were prominently enhanced in mTg-NE-treated mice.

CONCLUSION

This study indicates that a low dose of mTg in NE can significantly enhance antigen uptake and Tregs, resulting in inhibition of experimental autoimmune thyroiditis development.

Nanostructured SBA-15 silica as an adjuvant in immunizations with hepatitis B vaccine

ABSTRACT Objective: To evaluate the applicability of SBA-15 silica as an adjuvant in immunizations with purified particles of the viral protein HBsAg, the main component of hepatitis B vaccine, Butang®, produced by Instituto Butantan. Methods: BALB/c mice orally or subcutaneously received 0.5 μg of HBsAg adsorbed/encapsulated to SBA-15 or adsorbed to Al(OH)3. To assess the secondary immune response, a subcutaneous booster was administered 30 days after the first immunization. Individual serum and fecal samples of each group were periodically collected for specific antibody titration by ELISA. Results: Analysis of secretory IgA showed that mice orally primed with HBsAg on SBA-15 had increased levels of specific antibodies in primary and secondary immune responses. Specific serum IgA and IgG titers in HBsAg:SBA-15-orally immunized mice reached higher levels after the booster, demonstrating the effectiveness of oral vaccination with the use of silica. All immunized groups showed higher IgG1 levels. Conclusion: Our results clearly indicate the promising use of SBA-15 as an adjuvant, especially in oral immunizations.

PLGA, PLGA-TMC and TMC-TPP nanoparticles differentially modulate the outcome of nasal vaccination by inducing tolerance or enhancing humoral immunity

Development of vaccines in autoimmune diseases has received wide attention over the last decade. However, many vaccines showed limited clinical efficacy. To enhance vaccine efficacy in infectious diseases, biocompatible and biodegradable polymeric nanoparticles have gained interest as antigen delivery systems. We investigated in mice whether antigen-encapsulated PLGA (poly-lactic-co-glycolic acid), PLGA-TMC (N-trimethyl chitosan) or TMC-TPP (tri-polyphosphate) nanoparticles can also be used to modulate the immunological outcome after nasal vaccination. These three nanoparticles enhanced the antigen presentation by dendritic cells, as shown by increased in vitro and in vivo CD4⁺ T-cell proliferation. However, only nasal PLGA nanoparticles were found to induce an immunoregulatory response as shown by enhanced Foxp3 expression in the nasopharynx associated lymphoid tissue and cervical lymph nodes. Nasal administration of OVA-containing PLGA particle resulted in functional suppression of an OVA-specific Th-1 mediated delayed-type hypersensitivity reaction, while TMC-TPP nanoparticles induced humoral immunity, which coincided with the enhanced generation of OVA-specific B-cells in the cervical lymph nodes. Intranasal treatment with Hsp70-mB29a peptide-loaded PLGA nanoparticles suppressed proteoglycan-induced arthritis, leading to a significant reduction of disease. We have uncovered a role for PLGA nanoparticles to enhance CD4⁺ T-cell mediated immunomodulation after nasal application. The exploitation of this differential regulation of nanoparticles to modulate nasal immune responses can lead to innovative vaccine development for prophylactic or therapeutic vaccination in infectious or autoimmune diseases.

Immunomodulatory properties of vitamins, flavonoids and plant oils and their potential as vaccine adjuvants and delivery systems

INTRODUCTION

During the past century, vaccinologists have attempted to mimic pathogens in their immune-enhancing capacity. This led to the development of life-saving vaccines based on live attenuated viruses, bacteria and toxoids. Hence, intense research in vaccine adjuvant discovery has focused on toll like receptors, mutant toxins and viral and bacterial vectors. Nutritive components such as vitamins and select polyphenols also possess immunomodulating properties without the potential toxic and adverse side effects of agents that mimic danger signals.

AREAS COVERED

This review pertains to immunomodulatory properties of nutritive components, that is vitamins A, C, D, E, flavonoids and plant oils, as potential vaccine adjuvants and delivery systems, covering Pubmed publication searches from 1980 through 2011.

EXPERT OPINION

This relatively unexplored field of the potential of nutritive components as vaccine adjuvants holds great promise to promote the development of effective and above all safe vaccines. Hence the future focus should be placed on enhancing their efficacy, mainly through novel approaches in designing structural derivatives, formulations, delivery systems and routes of administration. As safety has been the major issue in development of novel vaccines, this new approach will probably result in new discoveries in designing safe and effective vaccines.

Do aluminum vaccine adjuvants contribute to the rising prevalence of autism?

Autism spectrum disorders (ASD) are serious multisystem developmental disorders and an urgent global public health concern. Dysfunctional immunity and impaired brain function are core deficits in ASD. Aluminum (Al), the most commonly used vaccine adjuvant, is a demonstrated neurotoxin and a strong immune stimulator. Hence, adjuvant Al has the potential to induce neuroimmune disorders. When assessing adjuvant toxicity in children, two key points ought to be considered: (i) children should not be viewed as "small adults" as their unique physiology makes them much more vulnerable to toxic insults; and (ii) if exposure to Al from only few vaccines can lead to cognitive impairment and autoimmunity in adults, is it unreasonable to question whether the current pediatric schedules, often containing 18 Al adjuvanted vaccines, are safe for children? By applying Hill's criteria for establishing causality between exposure and outcome we investigated whether exposure to Al from vaccines could be contributing to the rise in ASD prevalence in the Western world. Our results show that: (i) children from countries with the highest ASD prevalence appear to have the highest exposure to Al from vaccines; (ii) the increase in exposure to Al adjuvants significantly correlates with the increase in ASD prevalence in the United States observed over the last two decades (Pearson r=0.92, p<0.0001); and (iii) a significant correlation exists between the amounts of Al administered to preschool children and the current prevalence of ASD in seven Western countries, particularly at 3-4 months of age (Pearson r=0.89-0.94, p=0.0018-0.0248). The application of the Hill's criteria to these data indicates that the correlation between Al in vaccines and ASD may be causal. Because children represent a fraction of the population most at risk for complications following exposure to Al, a more rigorous evaluation of Al adjuvant safety seems warranted.

A novel inactivated intranasal respiratory syncytial virus vaccine promotes viral clearance without Th2 associated vaccine-enhanced disease

BACKGROUND

Respiratory syncytial virus (RSV) is a leading cause of bronchiolitis and pneumonia in young children worldwide, and no vaccine is currently available. Inactivated RSV vaccines tested in the 1960's led to vaccine-enhanced disease upon viral challenge, which has undermined RSV vaccine development. RSV infection is increasingly being recognized as an important pathogen in the elderly, as well as other individuals with compromised pulmonary immunity. A safe and effective inactivated RSV vaccine would be of tremendous therapeutic benefit to many of these populations.

PRINCIPAL FINDINGS

In these preclinical studies, a mouse model was utilized to assess the efficacy of a novel, nanoemulsion-adjuvanted, inactivated mucosal RSV vaccine. Our results demonstrate that NE-RSV immunization induced durable, RSV-specific humoral responses, both systemically and in the lungs. Vaccinated mice exhibited increased protection against subsequent live viral challenge, which was associated with an enhanced Th1/Th17 response. In these studies, NE-RSV vaccinated mice displayed no evidence of Th2 mediated immunopotentiation, as has been previously described for other inactivated RSV vaccines.

CONCLUSIONS

These studies indicate that nanoemulsion-based inactivated RSV vaccination can augment viral-specific immunity, decrease mucus production and increase viral clearance, without evidence of Th2 immune mediated pathology.

"Nanoantibiotics": a new paradigm for treating infectious diseases using nanomaterials in the antibiotics resistant era

Despite the fact that we live in an era of advanced and innovative technologies for elucidating underlying mechanisms of diseases and molecularly designing new drugs, infectious diseases continue to be one of the greatest health challenges worldwide. The main drawbacks for conventional antimicrobial agents are the development of multiple drug resistance and adverse side effects. Drug resistance enforces high dose administration of antibiotics, often generating intolerable toxicity, development of new antibiotics, and requests for significant economic, labor, and time investments. Recently, nontraditional antibiotic agents have been of tremendous interest in overcoming resistance that is developed by several pathogenic microorganisms against most of the commonly used antibiotics. Especially, several classes of antimicrobial nanoparticles (NPs) and nanosized carriers for antibiotics delivery have proven their effectiveness for treating infectious diseases, including antibiotics resistant ones, in vitro as well as in animal models. This review summarizes emerging efforts in combating against infectious diseases, particularly using antimicrobial NPs and antibiotics delivery systems as new tools to tackle the current challenges in treating infectious diseases.

Intranasal immunization of ferrets with commercial trivalent influenza vaccines formulated in a nanoemulsion-based adjuvant

NB-1008 is a surfactant-stabilized soybean oil-in-water nanoemulsion (NE) adjuvant with influenza virus antigen incorporated into the NE by simple mixing. Intranasal administration of the antigen with NE adjuvant efficiently produces both mucosal and serum antibody responses as well as a robust cellular Th1 immune response. To demonstrate the adjuvant effect of the W(80)5EC NE, a killed commercial influenza vaccine for intramuscular administration (Fluzone or Fluvirin) was mixed with the W(80)5EC NE adjuvant and administered intranasally to naïve ferrets. After a single intranasal immunization, the adjuvanted influenza vaccine elicited elevated serum hemagglutination inhibition (HAI) geometric mean titers (GMTs) ranging from 196 to 905 for the three hemagglutinin (HA) antigens present in the vaccine, which are approximately 19- to 90-fold higher titers at 1/50 the standard intramuscular commercial nonadjuvanted influenza vaccine dose. Seroconversion rates of 67% to 100% were achieved against each of the three viral strains present. The adjuvanted nasal influenza vaccine also produced significant cross immunity to five other H3N2 influenza virus strains not present in the vaccine and produced sterile immunity after challenge with homologous live virus. No safety issues were observed in 249 ferrets receiving the adjuvanted influenza vaccine. These findings demonstrate the ability of W(80)5EC NE to adjuvant nasally administered influenza vaccine and provide a basis for studying the intranasal W(80)5EC-adjuvanted influenza vaccine in humans.

Evaluation of a novel non-penetrating electrode for use in DNA vaccination

Current progress in the development of vaccines has decreased the incidence of fatal and non-fatal infections and increased longevity. However, new technologies need to be developed to combat an emerging generation of infectious diseases. DNA vaccination has been demonstrated to have great potential for use with a wide variety of diseases. Alone, this technology does not generate a significant immune response for vaccination, but combined with delivery by electroporation (EP), can enhance plasmid expression and immunity. Most EP systems, while effective, can be invasive and painful making them less desirable for use in vaccination. Our lab recently developed a non-invasive electrode known as the multi-electrode array (MEA), which lies flat on the surface of the skin without penetrating the tissue. In this study we evaluated the MEA for its use in DNA vaccination using Hepatitis B virus as the infectious model. We utilized the guinea pig model because their skin is similar in thickness and morphology to humans. The plasmid encoding Hepatitis B surface antigen (HBsAg) was delivered intradermally with the MEA to guinea pig skin. The results show increased protein expression resulting from plasmid delivery using the MEA as compared to injection alone. Within 48 hours of treatment, there was an influx of cellular infiltrate in experimental groups. Humoral responses were also increased significantly in both duration and intensity as compared to injection only groups. While this electrode requires further study, our results suggest that the MEA has potential for use in electrically mediated intradermal DNA vaccination.

Progress towards a needle-free hepatitis B vaccine

Hepatitis B virus (HBV) infection is a worldwide public health problem. Vaccination is the most efficient way to prevent hepatitis B. Despite the success of the currently available vaccine, there is a clear need for the development of new generation of HBV vaccines. Needle-free immunization is an attractive approach for mass immunization campaigns, since avoiding the use of needles reduces the risk of needle-borne diseases and prevents needle-stick injuries and pain, thus augmenting patient compliance and eliminating the need for trained medical personnel. Moreover, this kind of immunization was shown to induce good systemic as well as mucosal immunological responses, which is important for the creation of both a prophylactic and therapeutic vaccine. In order to produce a better, safer, more efficient and more suitable vaccine, adjuvants have been used. In this article, several adjuvants tested over the years for their potential to help create a needle-free vaccine against HBV are reviewed.

Viral nanoparticles and virus-like particles: platforms for contemporary vaccine design

Current vaccines that provide protection against infectious diseases have primarily relied on attenuated or inactivated pathogens. Virus‐like particles (VLPs), comprised of capsid proteins that can initiate an immune response but do not include the genetic material required for replication, promote immunogenicity and have been developed and approved as vaccines in some cases. In addition, many of these VLPs can be used as molecular platforms for genetic fusion or chemical attachment of heterologous antigenic epitopes. This approach has been shown to provide protective immunity against the foreign epitopes in many cases. A variety of VLPs and virus‐based nanoparticles are being developed for use as vaccines and epitope platforms. These particles have the potential to increase efficacy of current vaccines as well as treat diseases for which no effective vaccines are available. WIREs Nanomed Nanobiotechnol 2011 3 174–196 DOI: 10.1002/wnan.119

This article is categorized under: 1

Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease

A comparison of methods for purification and concentration of norovirus GII-4 capsid virus-like particles

Noroviruses (NoVs) are one of the leading causes of acute gastroenteritis worldwide. NoV GII-4 VP1 protein was expressed in a recombinant baculovirus system using Sf9 insect cells. Several methods for purification and concentration of virus-like particles (VLPs) were evaluated. Electron microscopy (EM) and histo-blood group antigen (HBGA) binding assays showed that repeated sucrose gradient purification followed by ultrafiltration resulted in intact VLPs with excellent binding to H type 3 antigens. VLPs were stable for at least 12 months at 4°C, and up to 7 days at ambient temperature. These findings indicate that this method yielded stable and high-quality VLPs.

Nanoparticle delivery systems in cancer vaccines

Therapeutic strategies that involve the manipulation of the host's immune system are gaining momentum in cancer research. Antigen-loaded nanocarriers are capable of being actively taken up by antigen-presenting cells (APCs) and have shown promising potential in cancer immunotherapy by initiating a strong immunostimulatory cascade that results in potent antigen-specific immune responses against the cancer. Such carrier systems offer versatility in that they can simultaneously co-deliver adjuvants with the antigens to enhance APC activation and maturation. Furthermore, modifying the surface properties of these nanocarriers affords active targeting properties to APCs and/or enhanced accumulation in solid tumors. Here, we review some recent advances in these colloidal and particulate nanoscale systems designed for cancer immunotherapy and the potential for these systems to translate into clinical cancer vaccines.

Evaluation of ISCOM vaccines for mucosal immunization against hepatitis B

Immune stimulating complexes (ISCOMs) incorporating recombinant hepatitis B surface antigen (HBsAg) was prepared for induction of humoral, cellular and mucosal immunity by intranasal administration. Prepared ISCOMs were characterized for its size, shape, incorporation efficiency, zeta potential, and antigen integrity. Designed ISCOMs possessed negative zeta potential (-21.7 mV) and an average size of 44.1 nm with antigen incorporation efficiency approximately 39 %. Serum anti-HBsAg IgG titer after three high nasal doses of ISCOMs was comparable with titer recorded after alum-HBsAg administered subcutaneously. Similarly, modest but higher cellular response (cytokines level in spleen homogenates) and significantly higher secretory sIgA response in mucosal secretions was observed (P < 0.001) in case of HBsAg ISCOM vaccines. Whereas, alum-HBsAg vaccine did not elicit considerable cellular or mucosal response. Thus, ISCOMs produced humoral, mucosal, and cellular immune responses upon nasal administration although high and multidose administrations were required to elicit potent immune responses. These data demonstrate potential of ISCOMs in their use as a carrier adjuvant for nasal subunit vaccines against hepatitis B.

Characterization of stability and nasal delivery systems for immunization with nanoemulsion-based vaccines

BACKGROUND

Many infectious diseases that cause significant morbidity and mortality, especially in the developing world, could be preventable through vaccination. The effort to produce safe, thermally stable, and needle-free mucosal vaccines has become increasingly important for global health considerations. We have previously demonstrated that a thermally stable nanoemulsion, a mucosal adjuvant for needle-free nasal immunization, is safe and induces protective immunity with a variety of antigens, including recombinant protein. The successful use of nanoemulsion-based vaccines, however, poses numerous challenges. Among the challenges is optimization of the formulation to maintain thermal stability and potency and another is accuracy and efficiency of dispensing the vaccines to the nasal mucosa in the anterior and turbinate region of the nasal cavity or potentially to the nasopharynx-associated lymphoid tissue.

METHODS

We have examined the effects of different diluents [phosphate-buffered saline (PBS) and 0.9% NaCl] on the stability and potency of nanoemulsion-based vaccines. In addition, we have determined the efficiency of delivering them using commercially available nasal spray devices (Pfeiffer SAP-62602 multidose pump and the BD Hypak SCF 0.5 ml unit dose Accuspray(TM)).

RESULTS

We report the stability and potency of PBS-diluted ovalbumin-nanomeulsion mixtures for up to 8 months and NaCl-diluted mixtures up to 6 months when stored at room temperature. Significant differences in spray characteristics including droplet size, spray angle, plume width, and ovality ratios were observed between the two pumps. Further, we have demonstrated that the nanoemulsion-based vaccines are not physically or chemically altered and retain potency following actuation with nasal spray devices. Using either device, the measured spray characteristics suggest deposition of nanoemulsion-based vaccines in inductive tissues located in the anterior region of the nasal cavity.

CONCLUSIONS

The results of this study suggest that nanoemulsion-based vaccines do not require specially engineered delivery devices and support their potential use as nasopharyngeal vaccine adjuvants.

Nanotechnology solutions for mucosal immunization

The current prevalence of infectious diseases in many developing regions of the world is a serious burden, impacting both the general health as well as economic growth of these communities. Additionally, treatment with conventional medication becomes increasingly challenging due to emergence of new and drug resistant strains jeopardizing the progress made in recent years towards control and elimination of certain types of infectious diseases. Thus, from a public health perspective, prevention such as through immunization by vaccination, which has proven to be most effective, might be the best alternative to prevent and combat infectious diseases in these regions. To achieve this, development of wide-scale immunization programs become necessary including vaccines that can easily and widely be distributed, stored and administered. Mucosal vaccines offer great potential since they can be administered via oral or intranasal delivery route which does not require trained personnel, avoids the use of needles and improves overall patient compliance and acceptance. However, it necessitates the implementation of specific immunization strategies to improve their efficacy. Application of nanotechnology to design and create particle mediated delivery systems that can efficiently encapsulate vaccine components for protection of the sensitive payload, target the mucosal immune system and incorporate mucosal adjuvants maximizing immune response is key strategy to improve the effectiveness of mucosal vaccines.

Nanoparticles and the immune system

Today nanotechnology is finding growing applications in industry, biology, and medicine. The clear benefits of using nanosized products in various biological and medical applications are often challenged by concerns about the lack of adequate data regarding their toxicity. One area of interest involves the interactions between nanoparticles and the components of the immune system. Nanoparticles can be engineered to either avoid immune system recognition or specifically inhibit or enhance the immune responses. We review herein reported observations on nanoparticle-mediated immunostimulation and immunosuppression, focusing on possible theories regarding how manipulation of particle physicochemical properties can influence their interaction with immune cells to attain desirable immunomodulation and avoid undesirable immunotoxicity.

Enhanced humoral and cellular immune responses after sublingual immunization against human papillomavirus 16 L1 protein with adjuvants

Needle-free nonparenteral vaccines offer a number of practical advantages, especially in developing countries. To address the effects of vaccine administration route, we tested mucosal and systemic immune responses against human papillomavirus 16 L1(HPV16L1) protein using intranasal, intravaginal, transdermal, sublingual (SL) and intramuscular routes. The SL route provided the most effective mucosal secretory IgA (sIgA) and serum IgG responses. After a 150 microg antigen dose via the SL route, saliva sIgA levels were 7.2- and 5.8-fold higher than those achieved via intravaginal and transdermal routes, respectively. Notably, SL administration even produced 4.6-fold higher levels of vaginal sIgA levels than did intravaginal delivery of 150 microg antigen. To enhance the immunogenicity of SL vaccines, we tested the adjuvanticity of nine molecules: three toll-like receptor agonists, three nucleotide-binding oligomerization-domain agonists, vitamin D3, poly-gamma-glutamic acid and cholera toxin subunit B (CTB). Among the molecules tested, CTB provided the most enhanced mucosal sIgA and systemic IgG induction. SL-applied CTB enhanced the production of interleukin-4 and interferon-gamma from stimulated CD4+ T cells. Moreover, interferon-gamma-producing CD8+ T cell responses were increased 1.7-fold after co-treatment with SL CTB and HPV16L1. These results suggest the potential of the SL route for delivery of HPV16L1 vaccines using CTB as an adjuvant.

Induction of immune response to the 17 kDa OMPA Burkholderia cenocepacia polypeptide and protection against pulmonary infection in mice after nasal vaccination with an OMP nanoemulsion-based vaccine

Burkholderia cepacia complex (Bcc) are opportunistic bacteria associated with life-threatening illness in persons with cystic fibrosis. Once Bcc colonization is established, these antimicrobial-resistant and biofilm-forming bacteria are difficult to eradicate and are associated with increased rates of morbidity and mortality. At present, no vaccines are available to prevent the Bcc infection. There is currently a paucity of published information regarding the development of vaccines designed to prevent Burkholderia colonization. This work expands on the recent studies published by Bertot et al. [Infect Immun 75(6):2740-2752, 2007], where successful protective immune responses were generated in mice using a B. multivorans OMP-based vaccine. Here, we evaluate an experimental mucosal vaccine against Bcc using a novel mucosal adjuvant (nanoemulsion) and a novel B. cenocepacia-based OMP antigen. The OMP antigen derived from B. cenocepacia was mixed with either nanoemulsion or with PBS and delivered intranasally to CD-1 mice. Serum analysis showed robust IgG and mucosal secretory IgA immune responses in vaccinated versus control mice. The antibodies had cross-neutralizing activity against both B. cenocepacia and B. multivorans species. We found that immunized mice were protected against pulmonary colonization with B. cenocepacia. We have also identified that a 17 kDa OmpA-like protein highly conserved between Burkholderia and Ralstonia species as a new immunodominant epitope in mucosal immunization.

Nanoparticles for nasal vaccination

The great interest in mucosal vaccine delivery arises from the fact that mucosal surfaces represent the major site of entry for many pathogens. Among other mucosal sites, nasal delivery is especially attractive for immunization, as the nasal epithelium is characterized by relatively high permeability, low enzymatic activity and by the presence of an important number of immunocompetent cells. In addition to these advantageous characteristics, the nasal route could offer simplified and more cost-effective protocols for vaccination with improved patient compliance. The use of nanocarriers provides a suitable way for the nasal delivery of antigenic molecules. Besides improved protection and facilitated transport of the antigen, nanoparticulate delivery systems could also provide more effective antigen recognition by immune cells. These represent key factors in the optimal processing and presentation of the antigen, and therefore in the subsequent development of a suitable immune response. In this sense, the design of optimized vaccine nanocarriers offers a promising way for nasal mucosal vaccination.

In vitro activities of a novel nanoemulsion against Burkholderia and other multidrug-resistant cystic fibrosis-associated bacterial species

Respiratory tract infection, most often involving opportunistic bacterial species with broad-spectrum antibiotic resistance, is the primary cause of death in persons with cystic fibrosis (CF). Species within the Burkholderia cepacia complex are especially problematic in this patient population. We investigated a novel surfactant-stabilized oil-in-water nanoemulsion (NB-401) for activity against 150 bacterial isolates recovered primarily from CF respiratory tract specimens. These specimens included 75 Burkholderia isolates and 75 isolates belonging to other CF-relevant species including Pseudomonas, Achromobacter, Pandoraea, Ralstonia, Stenotrophomonas, and Acinetobacter. Nearly one-third of the isolates were multidrug resistant, and 20 (13%) were panresistant based on standard antibiotic testing. All isolates belonging to the same species were genotyped to ensure that each isolate was a distinct strain. The MIC(90) of NB-401 was 125 microg/ml. We found no decrease in activity against multidrug-resistant or panresistant strains. MBC testing showed no evidence of tolerance to NB-401. We investigated the activity of NB-401 against a subset of strains grown as a biofilm and against planktonic strains in the presence of CF sputum. Although the activity of NB-401 was decreased under both conditions, the nanoemulsion remained bactericidal for all strains tested. These results support NB-401's potential role as a novel antimicrobial agent for the treatment of infection due to CF-related opportunistic pathogens.