Cancer Vaccines: Adjuvant Potency, Importance of Age, Lifestyle, and Treatments.

Although the discovery and characterization of multiple tumor antigens have sparked the development of many antigen/derived cancer vaccines, many are poorly immunogenic and thus, lack clinical efficacy. Adjuvants are therefore incorporated into vaccine formulations to trigger strong and long-lasting immune responses. Adjuvants have generally been classified into two categories: those that 'depot' antigens (e.g. mineral salts such as aluminum hydroxide, emulsions, liposomes) and those that act as immunostimulants (Toll Like Receptor agonists, saponins, cytokines). In addition, several novel technologies using vector-based delivery of antigens have been used. Unfortunately, the immune system declines with age, a phenomenon known as immunosenescence, and this is characterized by functional changes in both innate and adaptive cellular immunity systems as well as in lymph node architecture. While many of the immune functions decline over time, others paradoxically increase. Indeed, aging is known to be associated with a low level of chronic inflammation-inflamm-aging. Given that the median age of cancer diagnosis is 66 years and that immunotherapeutic interventions such as cancer vaccines are currently given in combination with or after other forms of treatments which themselves have immune-modulating potential such as surgery, chemotherapy and radiotherapy, the choice of adjuvants requires careful consideration in order to achieve the maximum immune response in a compromised environment. In addition, more clinical trials need to be performed to carefully assess how less conventional form of immune adjuvants, such as exercise, diet and psychological care which have all be shown to influence immune responses can be incorporated to improve the efficacy of cancer vaccines. In this review, adjuvants will be discussed with respect to the above-mentioned important elements.

Nanoparticles in dermatologic surgery.

Nanotechnology is an emerging branch of science that involves the engineering of functional systems on the nanoscale (1-100 nm). Nanotechnology has been used in biomedical and therapeutic agents with the aim of providing novel treatment solutions where small molecule size may be beneficial for modulation of biologic function. Recent investigation in nanomedicine has become increasingly important to cutaneous pathophysiology, such as functional designs directed towards skin cancers and wound healing. This review outlines the application of nanoparticles relevant to dermatologic surgery.

Convection-Enhanced Delivery of a Virus-Like Nanotherapeutic Agent with Dual-Modal Imaging for Besiegement and Eradication of Brain Tumors.

Convection-enhanced delivery (CED) is a promising technique for infusing a therapeutic agent directly into the brain, bypassing the blood-brain barrier (BBB) with a pressure gradient to increase drug concentration specifically around the brain tumor, thereby enhancing tumor inhibition and limiting the systemic toxicity of chemotherapeutic agents. Herein, we developed a dual-imaging monitored virus-like nanotherapeutic agent as an ideal CED infusate, which can be delivered to specifically besiege and eradicate brain tumors. Methods: We report one-pot fabrication of green-fluorescence virus-like particles (gVLPs) in Escherichia coli (E. coli) for epirubicin (EPI) loading, cell-penetrating peptide (CPP) modification, and 68Ga-DOTA labeling to form a positron emission tomography (PET)-fluorescence dual-imaging monitored virus-like nanotherapeutic agent (68Ga-DOTA labeled EPI@CPP-gVLPs) combined with CED for brain tumor therapy and image tracking. The drug delivery, cytotoxicity, cell uptake, biodistribution, PET-fluorescence imaging and anti-tumor efficacy of the 68Ga-DOTA labeled EPI@CPP-gVLPs were investigated in vitro and in vivo by using U87-MG glioma cell line and U87-MG tumor model. Results: The 68Ga-DOTA-labeled EPI@CPP-gVLPs showed excellent serum stability as an ideal CED infusate (30-40 nm in size), and can be disassembled through proteolytic degradation of the coat protein shell to enable drug release and clearance to minimize long-term accumulation. The present results indicated that 68Ga-DOTA-labeled EPI@CPP-gVLPs can provide a sufficiently high drug payload (39.2 wt% for EPI) and excellent detectability through fluorescence and PET imaging to accurately represent drug distribution during CED infusion. In vivo delivery of the 68Ga-DOTA-labeled EPI@CPP-gVLPs through CED demonstrated that the median survival was prolonged to over 50 days when the mice received two administrations (once per week) compared with the control group (median survival: 26 days). Conclusion: The results clearly indicated that a combination of 68Ga-DOTA-labeled EPI@CPP-gVLPs and CED can serve as a flexible and powerful synergistic treatment in brain tumors without evidence of systemic toxicity.

Live baculovirus acts as a strong B and T cell adjuvant for monomeric and oligomeric protein antigens.

Recombinant proteins produced by baculovirus (BV) expression systems contain residual BV after crude purification. We studied adjuvant effect of BV on antibody and T cell responses against two model antigens, monomeric ovalbumin (OVA) protein and oligomeric norovirus (NoV) virus-like particles (VLPs). BALB/c mice were immunized intradermally with OVA alone or OVA formulated with live or inactivated BV, and VLP formulations comprised of chromatographically purified NoV GII.4 VLPs alone or mixed with BV, or of crude purified VLPs containing BV impurities from expression system. Live BV improved immunogenicity of NoV VLPs, sparing VLP dose up to 10-fold. Moreover, soluble OVA protein induced IgG2a antibodies and T cell response only when co-administered with live BV. BV adjuvant effect was completely abrogated by removal or inactivation of BV. These findings support the usage of crude purified proteins containing residual BV as vaccine antigens.

Self-assembly of hexahistidine-tagged tobacco etch virus capsid protein into microfilaments that induce IgG2-specific response against a soluble porcine reproductive and respiratory syndrome virus chimeric protein.

BACKGROUND: Assembly of recombinant capsid proteins into virus-like particles (VLPs) still represents an interesting challenge in virus-based nanotechnologies. The structure of VLPs has gained importance for the development and design of new adjuvants and antigen carriers. The potential of Tobacco etch virus capsid protein (TEV CP) as adjuvant has not been evaluated to date. FINDINGS: Two constructs for TEV CP expression in Escherichia coli were generated: a wild-type version (TEV-CP) and a C-terminal hexahistidine (His)-tagged version (His-TEV-CP). Although both versions were expressed in the soluble fraction of E. coli lysates, only His-TEV-CP self-assembled into micrometric flexuous filamentous VLPs. In addition, the His-tag enabled high yields and facilitated purification of TEV VLPs. These TEV VLPs elicited broader IgG2-specific antibody response against a novel porcine reproductive and respiratory syndrome virus (PRRSV) protein when compared to the potent IgG1 response induced by the protein alone. CONCLUSIONS: His-TEV CP was purified by immobilized metal affinity chromatography and assembled into VLPs, some of them reaching 2-µm length. TEV VLPs administered along with PRRSV chimeric protein changed the IgG2/IgG1 ratio against the chimeric protein, suggesting that TEV CP can modulate the immune response against a soluble antigen.

Enhanced enterovirus 71 virus-like particle yield from a new baculovirus design.

Enterovirus 71 (EV71) is responsible for the outbreaks of hand-foot-and-mouth disease in the Asia-Pacific region. To produce the virus-like particle (VLP) vaccine, we previously constructed recombinant baculoviruses to co-express EV71 P1 polypeptide and 3CD protease using the Bac-to-Bac(®) vector system. The recombinant baculoviruses resulted in P1 cleavage by 3CD and subsequent VLP assembly in infected insect cells, but caused either low VLP yield or excessive VLP degradation. To tackle the problems, here we explored various expression cassette designs and flashBAC GOLD™ vector system which was deficient in v-cath and chiA genes. We found that the recombinant baculovirus constructed using the flashBAC GOLD™ system was insufficient to improve the EV71 VLP yield. Nonetheless, BacF-P1-C3CD, a recombinant baculovirus constructed using the flashBAC GOLD(TM) system to express P1 under the polh promoter and 3CD under the CMV promoter, dramatically improved the VLP yield while alleviating the VLP degradation. Infection of High Five(TM) cells with BacF-P1-C3CD enhanced the total and extracellular VLP yield to ≈268 and ≈171 mg/L, respectively, which enabled the release of abundant VLP into the supernatant and simplified the downstream purification. Intramuscular immunization of mice with 5 µg purified VLP induced cross-protective humoral responses and conferred protection against lethal virus challenge. Given the significantly improved extracellular VLP yield (≈171 mg/L) and the potent immunogenicity conferred by 5 µg VLP, one liter High Five(TM) culture produced ≈12,000 doses of purified vaccine, thus rendering the EV71 VLP vaccine economically viable and able to compete with inactivated virus vaccines.

Nanotherapeutics in the EU: an overview on current state and future directions.

The application of nanotechnology in areas of drug delivery and therapy (ie, nanotherapeutics) is envisioned to have a great impact on public health. The ability of nanotherapeutics to provide targeted drug delivery, improve drug solubility, extend drug half-life, improve a drug's therapeutic index, and reduce a drug's immunogenicity has resulted in the potential to revolutionize the treatment of many diseases. In this paper, we review the liposome-, nanocrystal-, virosome-, polymer therapeutic-, nanoemulsion-, and nanoparticle-based approaches to nanotherapeutics, which represent the most successful and commercialized categories within the field of nanomedicine. We discuss the regulatory pathway and initiatives endeavoring to ensure the safe and timely clinical translation of emerging nanotherapeutics and realization of health care benefits. Emerging trends are expected to confirm that this nano-concept can exert a macro-impact on patient benefits, treatment options, and the EU economy.

Virosome presents multimodel cancer therapy without viral replication.

A virosome is an artificial envelope that includes viral surface proteins and lacks the ability to produce progeny virus. Virosomes are able to introduce an encapsulated macromolecule into the cytoplasm of cells using their viral envelope fusion ability. Moreover, virus-derived factors have an adjuvant effect for immune stimulation. Therefore, many virosomes have been utilized as drug delivery vectors and adjuvants for cancer therapy. This paper introduces the application of virosomes for cancer treatment. In Particular, we focus on virosomes derived from the influenza and Sendai viruses which have been widely used for cancer therapy. Influenza virosomes have been mainly applied as drug delivery vectors and adjuvants. By contrast, the Sendai virosomes have been mainly applied as anticancer immune activators and apoptosis inducers.

Influenza virosomes as vaccine adjuvant and carrier system.

The basic concept of virosomes is the controlled in vitro assembly of virus-like particles from purified components. The first generation of influenza virosomes developed two decades ago is successfully applied in licensed vaccines, providing a solid clinical safety and efficacy track record for the technology. In the meantime, a second generation of influenza virosomes has evolved as a carrier and adjuvant system, which is currently applied in preclinical and clinical stage vaccine candidates targeting various prophylactic and therapeutic indications. The inclusion of additional components to optimize particle assembly, to stabilize the formulations, or to enhance the immunostimulatory properties have further improved and broadened the applicability of the platform.

Efficacy and safety of an intranasal virosomal respiratory syncytial virus vaccine adjuvanted with monophosphoryl lipid A in mice and cotton rats.

Respiratory syncytial virus infection remains a serious health problem, not only in infants but also in immunocompromised adults and the elderly. An effective and safe vaccine is not available due to several obstacles: non-replicating RSV vaccines may prime for excess Th2-type responses and enhanced respiratory disease (ERD) upon natural RSV infection of vaccine recipients. We previously found that inclusion of the Toll-like receptor 4 (TLR4) ligand monophosphoryl lipid A (MPLA) in reconstituted RSV membranes (virosomes) potentiates vaccine-induced immunity and skews immune responses toward a Th1-phenotype, without priming for ERD. As mucosal immunization is an attractive approach for induction of RSV-specific systemic and mucosal antibody responses and TLR ligands could potentiate such responses, we explored the efficacy and safety of RSV-MPLA virosomes administered intranasally (IN) to mice and cotton rats. In mice, we found that incorporation of MPLA in IN-administered RSV virosomes increased both systemic IgG and local secretory-IgA (S-IgA) antibody levels and resulted in significantly reduced lung viral titers upon live virus challenge. Also, RSV MPLA virosomes induced more Th1-skewed responses compared to responses induced by FI-RSV. Antibody responses and Th1/Th2-cytokine responses induced by RSV-MPLA virosomes were comparable to those induced by live RSV infection. By comparison, formalin-inactivated RSV (FI-RSV) induced serum IgG that inhibited viral shedding upon challenge, but also induced Th2-skewed responses. In cotton rats, similar effects of incorporation of MPLA in virosomes were observed with respect to induction of systemic antibodies and inhibition of lung viral shedding upon challenge, but mucosal sS-IgA responses were only moderately enhanced. Importantly, IN immunization with RSV-MPLA virosomes, like live virus infection, did not lead to any signs of ERD upon live virus challenge of vaccinated animals, whereas IM immunization with FI-RSV did induce severe lung immunopathology under otherwise comparable conditions. Taken together, these data show that mucosally administered RSV-MPLA virosomes hold promise for a safe and effective vaccine against RSV.

Micro/nanoparticle adjuvants for antileishmanial vaccines: present and future trends.

Leishmania infection continues to have a major impact on public health inducing significant morbidity and mortality mostly in the poorest populations. Drug resistance, toxicity and side effects associated with expensive chemotherapeutic treatments and difficult reservoir control emphasize the need for a safe and effective vaccine which is not available yet. Although, Leishmanization (LZ) was shown to be effective against cutaneous leishmaniasis, standardization and safety are the main problems of LZ. First generation killed parasites demonstrated limited efficacy in phase 3 trials and moreover well defined molecules have not reached to phase 3 yet. Limited efficacy in vaccines against leishmaniasis is partly due to lack of an appropriate adjuvant. Hence, the use of particulate delivery systems as carriers for antigen and/or immunostimulatory adjuvants for effective delivery to the antigen-presenting cells (APCs) is a valuable strategy to enhance vaccine efficacies. Particle-based delivery systems such as emulsions, liposomes, virosomes, and polymeric microspheres have the potential for successfully delivering antigens, which can then be further improved via incorporation of additional antigenic or immustimulatory adjuvant components in or onto the particle carrier system. In this review, we have attempted to provide a list of particulate vaccine delivery systems involved in the production of candidate leishmaniasis vaccines and introduced some potentially useful vaccine delivery systems for leishmaniasis in future experiments. In conclusion, combination vaccines (adjuvant systems) composed of candidate antigens and more importantly well-developed particulate delivery systems, such as lipid-based particles containing immunostimulatory adjuvants, have a chance to succeed as antileishmanial vaccines.

A virosomal vaccine against candidal vaginitis: immunogenicity, efficacy and safety profile in animal models.

A novel vaccine (PEV7) consisting of a truncated, recombinant aspartyl proteinase-2 of Candida albicans incorporated into influenza virosomes was studied. This vaccine candidate generated a potent serum antibody response in mouse and rat following intramuscular immunization. Anti-Sap2 IgG and IgA were also detected in the vaginal fluid of rats following intravaginal or intramuscular plus intravaginal administration. In a rat model of candidal vaginitis, PEV7 induced significant, long-lasting, likely antibody-mediated, protection following intravaginal route of immunization. PEV7 was also found to be safe in a repeated-dose toxicological study in rats. Overall, these data provide a sound basis to envisage the clinical development of this new candidate vaccine against candidal vaginitis.

Adjuvanted influenza vaccines.

The search for adjuvants has been stimulated by the need to ensure greater protection against influenza among subjects who show a reduced immune response to conventional influenza vaccines. Aluminum salts have long been used but are not considered satisfactory. This has led to the development of other possible compounds, sometimes on the basis of new knowledge concerning the mechanisms regulating the immune response to infections. Some of the new adjuvants (emulsions and virosomes) have been widely evaluated, and the apparently good results have led to the registration of adjuvanted influenza vaccines for use in humans, at least in some countries and in some subjects. In other cases, the adjuvants have been mainly or exclusively studied in experimental animals, and are unlikely to be used in humans in the near future. However, even in the case of those for which a considerable amount of data are available, assessments of their superiority over conventional influenza vaccines have mainly been based on immunogenicity studies, and have not been confirmed by comparative, randomized, double-blind clinical trials. Moreover, the very few human data comparing different adjuvants are frequently conflicting. The aim of this review is to discuss the characteristics and advantages of the adjuvants that have so far been used and to describe some of the new adjuvants that are still in the development phase.

Matrix-M adjuvanted virosomal H5N1 vaccine confers protection against lethal viral challenge in a murine model.

BACKGROUND: A candidate pandemic influenza H5N1 vaccine should provide rapid and long-lasting immunity against antigenically drifted viruses. As H5N1 viruses are poorly immunogenic, this may require a combination of immune potentiating strategies. An attractive approach is combining the intrinsic immunogenicity of virosomes with another promising adjuvant to further boost the immune response. As regulatory authorities have not yet approved a surrogate correlate of protection for H5N1 vaccines, it is important to test the protective efficacy of candidate H5N1 vaccines in a viral challenge study. OBJECTIVES: This study investigated in a murine model the protective efficacy of Matrix-M adjuvanted virosomal influenza H5N1 vaccine against highly pathogenic lethal viral challenge. METHODS: Mice were vaccinated intranasally (IN) or intramuscularly (IM) with 7·5 µg and 30 µg HA of inactivated A/Vietnam/1194/2004 (H5N1) (NIBRG-14) virosomal adjuvanted vaccine formulated with or without 10 µg of Matrix-M adjuvant and challenged IN with the highly pathogenic A/Vietnam/1194/2004 (H5N1) virus. RESULTS AND CONCLUSIONS: IM vaccination provided protection irrespective of dose and the presence of Matrix-M adjuvant, whilst the IN vaccine required adjuvant to protect against the challenge. The Matrix-M adjuvanted vaccine induced a strong and cross-reactive serum antibody response indicative of seroprotection after both IM and IN administration. In addition, the IM vaccine induced the highest frequencies of influenza specific CD4+ and CD8+ T-cells. The results confirm a high potential of Matrix-M adjuvanted virosomal vaccines and support the progress of this vaccine into a phase 1 clinical trial.

Influenza virosomes as a vaccine adjuvant and carrier system.

Influenza virosomes have been used for more than 10 years in commercial vaccines. The technology has been further developed as a carrier and adjuvant system for subunit vaccines, in particular for synthetic peptides. The extensive amount of preclinical and clinical data supports the notion that influenza virosomes represent a platform technology that ensures robust and long-lasting immune responses against subunit antigens with an excellent safety profile. Structurally and functionally, virosomes are enveloped virus-like particles, although they are assembled in vitro. This unique feature ensures a tight control of their composition and at the same time provides the flexibility to adapt the particle to various types of antigens. The mode of action of virosomes is complex and includes carrier as well as immune-stimulatory functions.

Efficacy of injectable trivalent virosomal-adjuvanted inactivated influenza vaccine in preventing acute otitis media in children with recurrent complicated or noncomplicated acute otitis media.

BACKGROUND: Most cases of acute otitis media (AOM) follow an upper respiratory infection due to viruses, including influenza viruses. As effective and safe influenza vaccines are available, their use has been considered among the possible measures of AOM prophylaxis. OBJECTIVES: To evaluate the efficacy of an inactivated virosomal-adjuvanted influenza vaccine in preventing AOM in children with a history of noncomplicated recurrent AOM (rAOM) or rAOM complicated by spontaneous perforation. METHODS: In this prospective, randomized, single-blinded, placebo-controlled study, 180 children aged 1 to 5 years with a history of rAOM and previously unvaccinated against influenza were randomized to receive the inactivated virosomal-adjuvanted subunit influenza vaccine (n = 90) or no treatment (n = 90), and AOM-related morbidity was monitored every 4 to 6 weeks for 6 months. RESULTS: The number of children experiencing at least 1 AOM episode was significantly smaller in the vaccinated group (P < 0.001), as was the mean number of AOM episodes (P = 0.03), the mean number of AOM episodes without perforation (P < 0.001), and the mean number of antibiotic courses (P < 0.001); the mean duration of bilateral OME was significantly shorter (P = 0.03). The only factor that seemed to be associated with the significantly greater efficacy of influenza vaccine in preventing AOM was the absence of a history of recurrent perforation (crude odds ratio, P = 0.01; adjusted odds ratio, P = 0.006). CONCLUSIONS: The intramuscular administration of injectable trivalent inactivated virosomal-adjuvanted influenza vaccine in children with a history of rAOM significantly reduces AOM-related morbidity. However, the efficacy of this preventive measure seems to be reduced in children with rAOM associated with repeated tympanic membrane perforation.

[Development and preclinical study of new generation virosomal split influenza vaccine "Grifor"].

New Russian virosomal split vaccine against influenza "Grifor" was developed. The vaccine is represented by mix of highly purified protective external and internal antigens of influenza A (H1N1 and H3N2) and B viruses. Developed technology of manufacture allowed to provide presentation of external antigens of influenza virus in the form of virosomes, and presentation of internal antigens in the form of micelles with maximal preservation of their antigenic activity. Using electron microscopy, electrophoresis in 10% polyacrilamide gel with sodium dodecyl sulfate, and polymerase chain reaction, morphologic and biochemical properties of the vaccine were studied. Preclinical study, including assessment of antigenic characteristics of "Grifor" vaccine compared to vaccine "Vaxigrip" (France), was performed. It was established that administration of the vaccine did not result in death of experimental animals, decrease of body mass, development of pathologic (including inflammatory, dystrophic and necrobiotic) changes in viscera or render adverse effects on blood hematologic and biochemical parameters and on the immune system. The vaccine was not pyrogenic and allergenic, did not have local irritating effects. Obtained results supported the appropriateness of conducting the clinical trials of "Grifor" vaccine on limited number of volunteers.

Head-to-head comparison of four nonadjuvanted inactivated cell culture-derived influenza vaccines: effect of composition, spatial organization and immunization route on the immunogenicity in a murine challenge model.

In order to study the influence of antigen composition, spatial organization of antigen and the route of administration, four cell culture-derived, inactivated, nonadjuvanted influenza vaccine formulations, i.e. whole inactivated virus (WIV), split, subunit and virosome vaccines were prepared from a single antigen batch. We directly compared the immunogenicity and efficacy of these vaccine formulations after intramuscular (i.m.) or intranasal (i.n.) administration in mice. Prime and boost vaccination were followed by a potentially lethal homologous aerosol challenge. For all vaccines, the i.m. route induced higher serum humoral immune responses as compared to the i.n. route and protected all mice against challenge at a dose of 5 microg. Upon i.n. immunization only WIV and split vaccines induced detectable IgG titers and partial protection against challenge but only very low HI titers were induced in almost all mice. WIV induced mainly IgG2a/c titers via both routes, whereas split vaccine induced exclusively IgG1 titers via both routes. Subunit and virosome vaccines induced exclusively IgG1 via the i.m. route. Mucosal sIgA levels were only detected after i.n. vaccination with WIV. Furthermore, vaccines containing all viral components (WIV and split vaccine) induced higher serum HI titers and serum antibody titers than subunit and virosome vaccines. The differences in magnitude and quality of immune responses of split and WIV, having the same composition, are likely related to their distinct spatial organization. In conclusion, the direct comparison between WIV, split, subunit and virosomes, shows that the differences in immune responses between these well known influenza vaccines can be explained by both the composition and particulate structure of these vaccine formulations.

Development of a universal influenza A vaccine based on the M2e peptide fused to the papaya mosaic virus (PapMV) vaccine platform.

With the emergence of highly virulent influenza viruses and the consequent risk of pandemics, new approaches to designing universal influenza vaccines are urgently needed. In this report, we demonstrate the potential of using a papaya mosaic virus (PapMV) platform carrying the universal M2e influenza epitope (PapMV-CP-M2e) as a candidate flu vaccine. We show that PapMV-CP-M2e virus-like particles (VLPs) can induce production in mice of anti-M2e antibodies that can recognize influenza-infected cells. PapMV-CP-M2e discs made of 20 coat protein (CP) subunits were shown to be poorly immunogenic compared to PapMV-CP-M2e VLPs composed of several hundred CP subunits. We also show that addition of either alum or PapMV-CP VLPs as adjuvant dramatically increased the immunogenicity of PapMV-CP-M2e-containing vaccine, and led to 100% protection against a challenge of 4LD(50) with the WSN/33 strain. These results show, for the first time, the potential of a recombinant plant virus protein to serve as both peptide delivery system and adjuvant in the crucial field of influenza vaccine development.

Influenza virosomes as a combined vaccine carrier and adjuvant system for prophylactic and therapeutic immunizations.

Influenza virosomes are an efficient antigen carrier and adjuvant system that are approved for the use in human vaccines. Structurally, virosomes are spherical vesicles of approximately 150 nm in diameter, composed of a lipid membrane with integrated envelope proteins derived from influenza virus, predominantly hemagglutinin. The particle structure, together with the functions of hemagglutinin--receptor binding, pH-dependent fusion activity and immunostimulation--is responsible for the adjuvant effect of virosomes. In contrast to most other virus-like particles, virosomes are semisynthetic particles reconstituted in vitro from lipids and from virus-derived proteins. The production process has proven to be robust at industrial scale and fully compatible with Good Manufacturing Practice guidelines. At the same time, the formulation procedure is sufficiently flexible to allow modifications of the composition and structure for the intended use, including the positioning of the antigens of interest.