Combined adjuvant-delivery system for new generation vaccine antigens: alliance has its own advantage

Single-walled carbon nanotube-protein complex: A strategy to improve the immune response to protein in mice

Vaccines represent an effective tool for controlling disease infection. As a key component of vaccines, many types of adjuvants have been developed and used today. This study is designed to investigate the efficacy of single-walled carbon nanotubes (SWCNTs) as a new adjuvant. The results showed that SWCNT could adsorb the antigen by intermolecular action, and the adsorption rate was significantly higher after dispersion of the SWCNTs in a sonic bath. The titer of specific antibody of mice in the SWCNTs group was higher than that of the mice in the antigen control group, confirming the adjuvant efficacy of SWCNTs. During immunisation, the specific antibody was detected earlier in the mice of the SWCNTs group, especially when the amount of antigen was reduced. And it was proved that the titer of antibodies was higher after subcutaneous and intraperitoneal injection compared to intramuscular injection. Most importantly, the mice immunised with SWCNTs showed almost the same level of immunity as the mice in the FCA (Freund's complete adjuvant) group, indicating that the SWCNTs were an effective adjuvant. In addition, the mice in the SWCNT group maintained antibody levels for 90 days after the last booster vaccination and showed a good state of health during the observed period. We also found that the SWCNTs were able to induce macrophages activation and enhance antigen uptake by mouse peritoneal macrophages.

Self-assembling peptides: Perspectives regarding biotechnological applications and vaccine development

Self-assembly involves a set of molecules spontaneously interacting in a highly coordinated and dynamic manner to form a specific supramolecular structure having new and clearly defined properties. Many examples of this occur in nature and many more came from research laboratories, with their number increasing every day via ongoing research concerning complex biomolecules and the possibility of harnessing it when developing new applications. As a phenomenon, self-assembly has been described on very different types of molecules (biomolecules including), so this review focuses on what is known about peptide self-assembly, its origins, the forces behind it, how the properties of the resulting material can be tuned in relation to experimental considerations, some biotechnological applications (in which the main protagonists are peptide sequences capable of self-assembly) and what is yet to be tuned regarding their research and development.

Nucleoprotein as a Promising Antigen for Broadly Protective Influenza Vaccines

Annual vaccination is considered as the main preventive strategy against seasonal influenza. Due to the highly variable nature of major viral antigens, such as hemagglutinin (HA) and neuraminidase (NA), influenza vaccine strains should be regularly updated to antigenically match the circulating viruses. The influenza virus nucleoprotein (NP) is much more conserved than HA and NA, and thus seems to be a promising target for the design of improved influenza vaccines with broad cross-reactivity against antigenically diverse influenza viruses. Traditional subunit or recombinant protein influenza vaccines do not contain the NP antigen, whereas live-attenuated influenza vaccines (LAIVs) express the viral NP within infected cells, thus inducing strong NP-specific antibodies and T-cell responses. Many strategies have been explored to design broadly protective NP-based vaccines, mostly targeted at the T-cell mode of immunity. Although the NP is highly conserved, it still undergoes slow evolutionary changes due to selective immune pressure, meaning that the particular NP antigen selected for vaccine design may have a significant impact on the overall immunogenicity and efficacy of the vaccine candidate. In this review, we summarize existing data on the conservation of the influenza A viral nucleoprotein and review the results of preclinical and clinical trials of NP-targeting influenza vaccine prototypes, focusing on the ability of NP-specific immune responses to protect against diverse influenza viruses.

Development of a Novel Vaccine Candidates against Cardiobacterium valvarum through Reverse Vaccinology and Computational Approaches

Antibiotic resistance is a major public health concern that has resulted in high healthcare costs, increased mortality, and the emergence of novel bacterial diseases. Cardiobacterium valvarum, an antibiotic-resistant bacterium, is one of the leading causes of heart disease. Currently, there is no licensed vaccination against C. valvarum. In this research, an in silico-based vaccine was designed against C. valvarum using reverse vaccinology, bioinformatics, and immunoinformatics techniques. 4206 core proteins, 2027 nonredundant proteins, and 2179 redundant proteins were predicted. Among nonredundant proteins, 23 proteins were predicted in an extracellular membrane, 30 in the outer membrane, and 62 in the periplasmic membrane region. After applying several subtractive proteomics filters, two proteins, TonB-dependent siderophore receptor and hypothetical protein, were chosen for epitope prediction. In the epitope selection phase, B and T-cellepitopes were analyzed and shortlisted for vaccine design. The vaccine model was designed by linking selected epitopes with GPGPG linkers to avoid flexibility. Furthermore, the vaccine model was linked to cholera toxin B adjuvant to induce a proper immune response. The docking approach was utilized to analyze binding affinity to immune cell receptors. Molecular docking results predicted 12.75 kcal/mol for a Vaccine with MHC-I, 6.89 for a vaccine with MHC-II, and 19.51 vaccine with TLR-4. The MMGBSA estimated -94, -78, and -76 kcal/mol for TLR-4 and vaccine, MHC-I and vaccine, and MHC-II and vaccine, while the MMPBSA analysis estimated -97, -61, and -72 kcal/mol for TLR-4 with the vaccine, MHC-I with vaccine, and MHC-II with a vaccine. Molecular dynamic simulation analysis revealed that the designed vaccine construct has proper stability with immune cell receptors as it is essential for inducing an immune response. In conclusion, we observed that the model vaccine candidate has the potency to induce an immune response in the host. However, the study is designed purely on a computational basis; hence, experimental validation is strongly recommended.

Production of a promising modular proteinaceous self-assembled delivery system for vaccination

Recently, there have been enormous advances in nano-delivery materials, especially safer and more biocompatible protein-based nanoparticles. Generally, proteinaceous nanoparticles (such as ferritin and virus-like particles) are self-assembled from some natural protein monomers. However, to ensure their capability of assembly, it is difficult to upgrade the protein structure through major modifications. Here, we have developed an efficient orthogonal modular proteinaceous self-assembly delivery system that could load antigens with an attractive coupling strategy. In brief, we constructed a nanocarrier by fusing two orthogonal domains-a pentameric cholera toxin B subunit and a trimer forming peptide-and an engineered streptavidin monomer for binding biotinylated antigens. After successfully preparing the nanoparticles, the receptor-binding domain of SARS-CoV-2 spike protein and influenza virus haemagglutination antigen are used as model antigens for further evaluation. We found that the biotinylated antigen is able to bind to the nanoparticles with high affinity and achieve efficient lymph node drainage when loaded on the nanoparticles. Then, T cells are greatly activated and the formation of germinal centers is observed. Experiments of two mouse models demonstrate the strong antibody responses and prophylactic effects of these nanovaccines. Thus, we establish a proof-of-concept for the delivery system with the potential to load diverse antigen cargos to generate high-performance nanovaccines, thereby offering an attractive platform technology for nanovaccine preparation.

Recent Advances in Cancer Vaccines: Challenges, Achievements, and Futuristic Prospects

Cancer is a chronic disease, and it can be lethal due to limited therapeutic options. The conventional treatment options for cancer have numerous challenges, such as a low blood circulation time as well as poor solubility of anticancer drugs. Therapeutic cancer vaccines emerged to try to improve anticancer drugs' efficiency and to deliver them to the target site. Cancer vaccines are considered a viable therapeutic technique for most solid tumors. Vaccines boost antitumor immunity by delivering tumor antigens, nucleic acids, entire cells, and peptides. Cancer vaccines are designed to induce long-term antitumor memory, causing tumor regression, eradicate minimal residual illness, and prevent non-specific or unpleasant effects. These vaccines can assist in the elimination of cancer cells from various organs or organ systems in the body, with minimal risk of tumor recurrence or metastasis. Vaccines and antigens for anticancer therapy are discussed in this review, including current vaccine adjuvants and mechanisms of action for various types of vaccines, such as DNA- or mRNA-based cancer vaccines. Potential applications of these vaccines focusing on their clinical use for better therapeutic efficacy are also discussed along with the latest research available in this field.

Immune enhancement of N-2-Hydroxypropyl trimethyl ammonium chloride chitosan/carboxymethyl chitosan nanoparticles vaccine

The immunogenicity and toxicity of N-2-Hydroxypropyl trimethyl ammonium chloride chitosan/N, O-carboxymethyl chitosan nanoparticles (N-2-HACC/CMCS NPs) as a universal vaccine adjuvant/delivery system remains unclear. The present study indicated that the positively charged N-2-HACC/CMCS NPs showed a regular spherical morphology, with a particle size of 219 ± 13.72 nm, zeta potential of 37.28 ± 4.58 mV, had hemocompatibility and biodegradation. Acute toxicity, repeated dose toxicity, abnormal toxicity, muscle stimulation, whole body allergic reaction evaluation in vitro, and cytotoxicity in vivo confirmed N-2-HACC/CMCS NPs is safe and non-toxic. N-2-HACC/OVA/CMCS NPs were prepared to evaluate the immunogenicity, which showed a particle size of 248.1 ± 15.53 nm, zeta potential of 17.24 ± 1.28 mV, encapsulation efficiency of 92.43 ± 0.96 %, and loading capacity of 42.97 ± 0.07 %. Oral or intramuscular route with the N-2-HACC/OVA/CMCS NPs in mice not only induced higher IgG, IgG1, IgG2a, and sIgA antibody titers, but also significantly produced higher levels of IL-6, IL-4, IFN-γ, and TNF-α, demonstrating that the N-2-HACC/OVA/CMCS NPs enhance humoral, cellular, and mucosal immune responses. Our results not only support the N-2-HACC/CMCS NPs to be a safe and potential universal nano adjuvant/delivery system in vaccine development, especially mucosal vaccines, but also rich the database knowledge of adjuvant/delivery systems, and provide new direction to introduce more licensed adjuvants.

Nanovaccine Delivery Approaches and Advanced Delivery Systems for the Prevention of Viral Infections: From Development to Clinical Application

Viral infections causing pandemics and chronic diseases are the main culprits implicated in devastating global clinical and socioeconomic impacts, as clearly manifested during the current COVID-19 pandemic. Immunoprophylaxis via mass immunisation with vaccines has been shown to be an efficient strategy to control such viral infections, with the successful and recently accelerated development of different types of vaccines, thanks to the advanced biotechnological techniques involved in the upstream and downstream processing of these products. However, there is still much work to be done for the improvement of efficacy and safety when it comes to the choice of delivery systems, formulations, dosage form and route of administration, which are not only crucial for immunisation effectiveness, but also for vaccine stability, dose frequency, patient convenience and logistics for mass immunisation. In this review, we discuss the main vaccine delivery systems and associated challenges, as well as the recent success in developing nanomaterials-based and advanced delivery systems to tackle these challenges. Manufacturing and regulatory requirements for the development of these systems for successful clinical and marketing authorisation were also considered. Here, we comprehensively review nanovaccines from development to clinical application, which will be relevant to vaccine developers, regulators, and clinicians.

B19-VLPs as an effective delivery system for tumour antigens to induce humoral and cellular immune responses against triple negative breast cancer

Cancer immunotherapy is emerging as a viable treatment option for several types of cancer. Active immunotherapy aims for the induction of specific antitumor immune responses; this goal requires strategies capable of increasing the immunogenicity of tumour antigens. Parvovirus B19 virus-like particles (B19-VLPs) formed of VP2 protein had been shown to be an effective multi-neoepitope delivery system capable of inducing specific cellular responses towards coupled antigens and reducing tumour growth and lung metastases in triple negative breast cancer mouse model. These findings encouraged us to further characterise these VP2 B19-VLPs by testing their capacity to simultaneously induce cellular and humoral responses towards other tumour-associated antigens, as this had not yet been evaluated. Here, we designed and evaluated in the 4T1 breast cancer model the prophylactic and therapeutic effect of VP2 B19-VLPs decorated with cellular (P53) and humoral (MUC1) epitopes. Balb/c mice were immunised with chimaeric VLPs, vehicle, or VLPs plus adjuvant. Tumour establishment and growth, lung metastasis, and cellular and humoral immune responses were evaluated. The prophylactic administration of chimaeric VLPs without adjuvant prevented the establishment of the tumour, while by therapeutic administration, chimaeric VLPs induced smaller tumour growth and decreased the number of metastases in the lung compared to wild-type VLPs. chimaeric VLPs induced high antibody titres towards the MUC1 epitope, as well as specific cellular responses towards P53 epitopes in lymph nodes local to the tumour. Our results reinforce and extend the utility of VP2 B19-VLPs as an encouraging tumour antigen delivery system in cancer immunotherapy able to improve tumour immunity in TNBC by inducing cellular and humoral immune responses.

Nanotechnology-empowered vaccine delivery for enhancing CD8+ T cells-mediated cellular immunity

After centuries of development, using vaccination to stimulate immunity has become an effective method for prevention and treatment of a variety of diseases including infective diseases and cancers. However, the tailor-made efficient delivery system for specific antigens is still urgently needed due to the low immunogenicity and stability of antigens, especially for vaccines to induce CD8⁺ T cells-mediated cellular immunity. Unlike B cells-mediated humoral immunity, CD8⁺ T cells-mediated cellular immunity mainly aims at the intracellular antigens from microorganism in virus-infected cells or genetic mutations in tumor cells. Therefore, the vaccines for stimulating CD8⁺ T cells-mediated cellular immunity should deliver the antigens efficiently into the cytoplasm of antigen presenting cells (APCs) to form major histocompatibility complex I (MHCI)-antigen complex through cross-presentation, followed by activating CD8⁺ T cells for immune protection and clearance. Importantly, nanotechnology has been emerged as a powerful tool to facilitate these multiple processes specifically, allowing not only enhanced antigen immunogenicity and stability but also APCs-targeted delivery and elevated cross-presentation. This review summarizes the process of CD8⁺ T cells-mediated cellular immunity induced by vaccines and the technical advantages of nanotechnology implementation in general, then provides an overview of the whole spectrum of nanocarriers studied so far and the recent development of delivery nanotechnology in vaccines against infectious diseases and cancer. Finally, we look forward to the future development of nanotechnology for the next generation of vaccines to induce CD8⁺ T cells-mediated cellular immunity.

Platforms for Production of Protein-Based Vaccines: From Classical to Next-Generation Strategies

To date, vaccination has become one of the most effective strategies to control and reduce infectious diseases, preventing millions of deaths worldwide. The earliest vaccines were developed as live-attenuated or inactivated pathogens, and, although they still represent the most extended human vaccine types, they also face some issues, such as the potential to revert to a pathogenic form of live-attenuated formulations or the weaker immune response associated with inactivated vaccines. Advances in genetic engineering have enabled improvements in vaccine design and strategies, such as recombinant subunit vaccines, have emerged, expanding the number of diseases that can be prevented. Moreover, antigen display systems such as VLPs or those designed by nanotechnology have improved the efficacy of subunit vaccines. Platforms for the production of recombinant vaccines have also evolved from the first hosts, Escherichia coli and Saccharomyces cerevisiae, to insect or mammalian cells. Traditional bacterial and yeast systems have been improved by engineering and new systems based on plants or insect larvae have emerged as alternative, low-cost platforms. Vaccine development is still time-consuming and costly, and alternative systems that can offer cost-effective and faster processes are demanding to address infectious diseases that still do not have a treatment and to face possible future pandemics.

Manganese salts function as potent adjuvants

Aluminum-containing adjuvants have been used for nearly 100 years to enhance immune responses in billions of doses of vaccines. To date, only a few adjuvants have been approved for use in humans, among which aluminum-containing adjuvants are the only ones widely used. However, the medical need for potent and safe adjuvants is currently continuously increasing, especially those triggering cellular immune responses for cytotoxic T lymphocyte activation, which are urgently needed for the development of efficient virus and cancer vaccines. Manganese is an essential micronutrient required for diverse biological activities, but its functions in immunity remain undefined. We previously reported that Mn2+ is important in the host defense against cytosolic dsDNA by facilitating cGAS-STING activation and that Mn2+ alone directly activates cGAS independent of dsDNA, leading to an unconventional catalytic synthesis of 2'3'-cGAMP. Herein, we found that Mn2+ strongly promoted immune responses by facilitating antigen uptake, presentation, and germinal center formation via both cGAS-STING and NLRP3 activation. Accordingly, a colloidal manganese salt (Mn jelly, MnJ) was formulated to act not only as an immune potentiator but also as a delivery system to stimulate humoral and cellular immune responses, inducing antibody production and CD4+/CD8+ T-cell proliferation and activation by either intramuscular or intranasal immunization. When administered intranasally, MnJ also worked as a mucosal adjuvant, inducing high levels of secretory IgA. MnJ showed good adjuvant effects for all tested antigens, including T cell-dependent and T cell-independent antigens, such as bacterial capsular polysaccharides, thus indicating that it is a promising adjuvant candidate.

Cytotoxic T-lymphocyte elicited therapeutic vaccine candidate targeting cancer against MAGE-A11 carcinogenic protein

Immunotherapy is a breakthrough approach for cancer treatment and prevention. By exploiting the fact that cancer cells have overexpression of tumor antigens responsible for its growth and progression, which can be identified and removed by boosting the immune system. In silico techniques have provided efficient ways for developing preventive measures to ward off cancer. Herein, we have designed a potent cytotoxic T-lymphocyte epitope to elicit a desirable immune response against carcinogenic melanoma-associated antigen-A11. Potent epitope was predicted using reliable algorithms and characterized by advanced computational avenue CABS molecular dynamics simulation, for full flexible binding with HLA-A*0201 and androgen receptor to large-scale rearrangements of the complex system. Results showed the potent immunogenic construct (KIIDLVHLL), from top epitopes using five algorithms. Molecular docking analyses showed the strong binding of epitope with HLA-A*0201 and androgen receptor with docking score of -780.6 and -641.06 kcal/mol, respectively. Molecular dynamics simulation analysis revealed strong binding of lead epitope with androgen receptor by involvement of 127 elements through atomic-model study. Full flexibility study showed stable binding of epitope with an average root mean square deviation (RMSD) 2.21 Å and maximum RMSD value of 6.48 Å in optimal cluster density area. The epitope also showed remarkable results with radius of gyration 23.0777 Å, world population coverage of 39.08% by immune epitope database, and transporter associated with antigen processing (TAP) affinity IC50 value of 2039.65 nm. Moreover, in silico cloning approach confirmed the expression and translation capacity of the construct within a suitable expression vector. The present study paves way for a potential immunogenic construct for prevention of cancer.

An Overview of Nanocarrier-Based Adjuvants for Vaccine Delivery

The development of vaccines is one of the most significant medical accomplishments which has helped to eradicate a large number of diseases. It has undergone an evolutionary process from live attenuated pathogen vaccine to killed whole organisms or inactivated toxins (toxoids), each of them having its own advantages and disadvantages. The crucial parameters in vaccination are the generation of memory response and protection against infection, while an important aspect is the effective delivery of antigen in an intelligent manner to evoke a robust immune response. In this regard, nanotechnology is greatly contributing to developing efficient vaccine adjuvants and delivery systems. These can protect the encapsulated antigen from the host’s in-vivo environment and releasing it in a sustained manner to induce a long-lasting immunostimulatory effect. In view of this, the present review article summarizes nanoscale-based adjuvants and delivery vehicles such as viral vectors, virus-like particles and virosomes; non-viral vectors namely nanoemulsions, lipid nanocarriers, biodegradable and non-degradable nanoparticles, calcium phosphate nanoparticles, colloidally stable nanoparticles, proteosomes; and pattern recognition receptors covering c-type lectin receptors and toll-like receptors.

The Synergistic Effects of Sulfated Lactosyl Archaeol Archaeosomes When Combined with Different Adjuvants in a Murine Model

Archaeosomes, composed of sulfated lactosyl archaeol (SLA) glycolipids, have been proven to be an effective vaccine adjuvant in multiple preclinical models of infectious disease or cancer. SLA archaeosomes are a promising adjuvant candidate due to their ability to strongly stimulate both humoral and cytotoxic immune responses when simply admixed with an antigen. In the present study, we evaluated whether the adjuvant effects of SLA archaeosomes could be further enhanced when combined with other adjuvants. SLA archaeosomes were co-administered with five different Toll-like Receptor (TLR) agonists or the saponin QS-21 using ovalbumin as a model antigen in mice. Both humoral and cellular immune responses were greatly enhanced compared to either adjuvant alone when SLA archaeosomes were combined with either the TLR3 agonist poly(I:C) or the TLR9 agonist CpG. These results were also confirmed in a separate study using Hepatitis B surface antigen (HBsAg) and support the further evaluation of these adjuvant combinations.

The Importance of Poly(ethylene glycol) and Lipid Structure in Targeted Gene Delivery to Lymph Nodes by Lipid Nanoparticles

Targeted delivery of nucleic acids to lymph nodes is critical for the development of effective vaccines and immunotherapies. However, it remains challenging to achieve selective lymph node delivery. Current gene delivery systems target mainly to the liver and typically exhibit off-target transfection at various tissues. Here we report novel lipid nanoparticles (LNPs) that can deliver plasmid DNA (pDNA) to a draining lymph node, thereby significantly enhancing transfection at this target organ, and substantially reducing gene expression at the intramuscular injection site (muscle). In particular, we discovered that LNPs stabilized by 3% Tween 20, a surfactant with a branched poly(ethylene glycol) (PEG) chain linking to a short lipid tail, achieved highly specific transfection at the lymph node. This was in contrast to conventional LNPs stabilized with a linear PEG chain and two saturated lipid tails (PEG-DSPE) that predominately transfected at the injection site (muscle). Interestingly, replacing Tween 20 with Tween 80, which has a longer unsaturated lipid tail, led to a much lower transfection efficiency. Our work demonstrates the importance of PEGylation in selective organ targeting of nanoparticles, provides new insights into the structure-property relationship of LNPs, and offers a novel, simple, and practical PEGylation technology to prepare the next generation of safe and effective vaccines against viruses or tumours.

Design and optimization of a subunit vaccine targeting COVID-19 molecular shreds using an immunoinformatics framework

COVID-19 has been declared as a global health emergency and exposed the world to a deadly virus, which has dramatically changed the lives of humans for an unknown period of time. In the battleground with the virus, we have employed an immunoinformatics framework to design a robust vaccine as an insurance plan for the future. The pathogenic sequence with cryptic epitope taken from patients in Wuhan, China, was harnessed to design a promiscuous cytotoxic T-lymphocyte, helper T-lymphocyte, and B-cell epitope based subunit vaccine, engineered with adjuvants and conformational linkers. The reported vaccine has high antigenicity and immunogenicity profiles with potential TAP affinity, which ensures elevated antigen processing capability. It has strong binding with major histocompatibility complex (MHC) receptors (MHC-1 and MHC-2) and virus-specific membrane receptor TLR-2, with scores of -1010.7, -1035.7, and -1076.3 kcal mol-1, respectively. Molecular dynamics simulation analysis was used to assess the stable binding with TLR-2 with minimal atomic motions through a deformation plot, covariance matrix, and elastic network. Importantly, an in silico immunization assay showed the reliable elicitation of key players in terms of immune cells together with memory cells to evoke adaptive immune responses upon administration of the construct. In view of favorable outcomes, we also propose a plausible vaccine mechanism to elicit an immune response to fight coronavirus.

Improvements to the live-attenuated Newcastle disease virus vaccine using Carbopol® 940 as a stabilizer

Background and Aim:

One strategy that can be used to stabilize vaccines is to convert them into a dry powder. This can protect the integrity of the active ingredients as well as vaccine antigenicity during manufacture, storage, and transport. This study highlights the potent adjuvant activity of Carbopo^l® when used alone to stabilize live-attenuated Newcastle disease virus (NDV) vaccines or when used in a formulation together with skimmed milk. Tolerability and potency of these formulations were compared with those obtained from other local live NDV vaccines produced locally by the Veterinary Serum and Vaccine Research Institute.

Materials and Methods:

We evaluated the cellular and humoral immune responses to a locally prepared, live-attenuated LaSota virus vaccine. Vaccine formulations were stabilized with Carbopol^® 940 alone or in combination with skimmed milk.

Results:

Our results indicate that the use of Carbopol^® 940 alone to stabilize a live-attenuated LaSota vaccine resulted in enhanced cellular and humoral immunity. The antibody titer was prolonged through the 6^th week post-vaccination (5.0 log₂). Full (100%) protection was observed in response to challenge with very virulent NDV at day 21 after vaccination; there were no clinical signs or lesions on examination. Addition of Carbopol^® 940 to the live-attenuated vaccine formulation resulted in a more compact, stable, and high-quality lyophilized cake after freeze-dried lyophilization compared with that produced by stabilization with skimmed milk alone.

Conclusion:

Our data suggest that Carbopol^® 940 may improve clinical responses to live-attenuated vaccines.

Protein-only nanocapsules induce cross-presentation in dendritic cells, demonstrating potential as an antigen delivery system

Templating has been demonstrated to be an efficient method of nanocapsule preparation. However, there have been no reports of using protein-only nanocapsules as an antigen delivery system. Such a system would enable the delivery of antigen without additional polymers. This study focused on defining the structural and cellular characteristics of nanocapsules consisting of antigen (ovalbumin) alone, synthesized by the templating method using highly monodispersed solid core mesoporous shell (SC/MS) and mesoporous (MS) silica nanoparticles of 410 nm and 41 nm in diameter, respectively. The synthesized ovalbumin nanocapsules were homogeneous in structure, and cellular uptake was observed in DC2.4 murine immature dendritic cells with minimal cytotoxicity. The nanocapsules were localized intracellularly and induced antigen presentation by the cross-presentation pathway. The templating system, using SC/MS and MS silica nanoparticles, was demonstrated to be an effective nanocapsule synthesis method for a new antigen delivery system.

Current Progress in Particle-Based Systems for Transdermal Vaccine Delivery

Transcutaneous immunization (TCI) via needle-free and non-invasive drug delivery systems is a promising approach for overcoming the current limitations of conventional parenteral vaccination methods. The targeted access to professional antigen-presenting cell (APC) populations within the skin, such as Langerhans cells (LCs), various dermal dendritic cells (dDCs), macrophages, and others makes the skin an ideal vaccination site to specifically shape immune responses as required. The stratum corneum (SC) of the skin is the main penetration barrier that needs to be overcome by the vaccine components in a coordinated way to achieve optimal access to dermal APC populations that induce priming of T-cell or B-cell responses for protective immunity. While there are numerous approaches to penetrating the SC, such as electroporation, sono- or iontophoresis, barrier and ablative methods, jet and powder injectors, and microneedle-mediated transport, we will focus this review on the recent progress made in particle-based systems for TCI. This particular approach delivers vaccine antigens together with adjuvants to perifollicular APCs by diffusion and deposition in hair follicles. Different delivery systems including nanoparticles and lipid-based systems, for example, solid nano-emulsions, and their impact on immune cells and generation of a memory effect are discussed. Moreover, challenges for TCI are addressed, including timely and targeted delivery of antigens and adjuvants to APCs within the skin as well as a deeper understanding of the ill-defined mechanisms leading to the induction of effective memory responses.

Phoenix dactylifera, mentha piperita and montanide™ ISA-201 as immunological adjuvants in a chicken model

This study evaluated plant-based immune-adjuvants from crude extracts of Phoenix dactylifera and Mentha piperita as promising adjuvants for vaccines because of the limited side effects associated with plant extracts. In addition, Montanide™ ISA 201 previously used in vaccines in cattle. Eight different infectious coryza (IC) vaccines were prepared from three serovars [A (W strain and local strain), C (Modesto strain) and B (0222 strain)] with eight Avibacterium paragallinarum vaccines adjuvants formulae using liquid paraffin, Montanide™ ISA 71, Montanide™ ISA 201, and Montanide™ Gel adjuvants, P. dactylifera and M. piperita as immune-stimulants at a concentration of 1 mg and 2 mg incorporated with or without liquid paraffin oil as an adjuvant. These vaccines were applied in a chicken model. After a single immunization, the eight vaccine formulations were evaluated using the ELISA and Microplate agglutination test. Evidence of protection in the immunized birds was based on the results after challenge and bacterial isolation. The incorporation of the crude aqueous extract of P. dactylifera or M. piperita at a concentration of 2 mg in a liquid paraffin oil adjuvanted IC vaccine could be employed as an efficient adjuvant for chicken to IC vaccine to enhance immune responses. Also,Montanide™ ISA 201 may be the best adjuvant to be used to enhance the protective response against Av. paragallinarum. Our results confirm that aqueous extracts of M. piperita leaves and P. dactylifera fruit have immunomodulatory potentials in vivo and elevated serum antibodies against Av. Paragallinarum.

Multiepitope Subunit Vaccine to Evoke Immune Response against Acute Encephalitis

Acute encephalitis syndrome outbreak has emerged as a major health concern on both national and international scales. Brain inflammation/infections caused by Japanese encephalitis virus (JEV) can lead to death. The cases are growing in numbers globally, and this emergent health concern requires an effective and viable vaccine to strengthen the body's immune system against this deadly virus. Proteomic analyses of JEV revealed the envelope protein as a potential target for vaccine development by patient samples analysis. Hence, in this study, we aimed to design a multiepitope subunit vaccine for acute encephalitis using the advanced structural biology and immunoinformatics approaches. We report the multiepitope subunit vaccine consisted of the putative T-cell epitope (MHC-1 and MHC-2 restricted) and B-cell epitope and with high antigenicity and immunogenicity. The TAP affinity epitopes along with adjuvants were engineered to the vaccine, to ensure the ease transportation inside the host and elicitation of a strong immune response. The specificity of vaccine construct was evaluated by molecular docking with major histocompatibility complex (MHC) receptors and host membrane receptor TLR2. High docking scores and a close interaction to the binding groove of receptors confirmed the potency and specificity of the vaccine. Also, molecular dynamics simulation studies confirmed the stable interaction of vaccine with TLR2 for a long run (100 ns), which showed the prolonged elicitation of the strong immune response. Peptide dynamics studies showed the flexible, strong, and stable binding of vaccine with minimal deviation in root-mean-square deviation (RMSD), root-mean-square fluctuation (RMSF), and secondary structure estimation (SSE) plots till 100 ns simulation run. The in silico immune simulation approach based on the position-specific scoring matrix and machine learning methods resulted in the strong immune response reinforcement statistics of immune cells (T-cells, B-cells population, and memory cells) in response to vaccine candidate. The favorable results and well-correlated data of varied in silico techniques paved for a potent multiepitope vaccine and helped us to propose the mechanism of action of designed vaccine and generation of the immune response against acute encephalitis syndrome.

Antimicrobial Peptide Designing and Optimization Employing Large-Scale Flexibility Analysis of Protein-Peptide Fragments

The mankind relies on the use of antibiotics for a healthy life. The epidemic-like emergence of drug-resistant bacterial strains is increasingly becoming one of the leading causes of morbidity and mortality, which gives rise to design a potential antimicrobial peptide (AMP). Here, we have designed the potential AMP using the extensive dynamics simulation since protein-peptide interactions are linked to large conformational changes. Therefore, we have employed the advanced computational avenue CABS molecular docking method that enabled the flexible peptide-protein molecular docking with a large-scale rearrangement of the protein. Lead AMP was investigated against the wild-type (WT) and mutant-PBP5 (MT-PBP5) proteins (antiresistance property). AMP20 showed strong interactions with wtPBP5 and mtPBP5 and involvement of a large number of elements in interactions determined through an atomic model study. Full flexibility analysis showed the stable interaction of AMP20 with both the wild-type and mutant form of PBP5 with root-mean-square deviation (RMSD) values of ∼4.51 and 4.85 Å, respectively. Moreover, peptide dynamics showed involvement of all residues of AMP20 through contact map analysis, and extensive simulation confirmed the stable interaction of AMP20, with lower values of RMSD, radius of gyration, and root-mean-square fluctuation. This study paves the way for a potential approach to design the AMP with amino acid walking and large-scale conformational rearrangements of amino acids.

Combined vaccines for prophylaxis of infectious conditions

In recent years, the application of vaccines shows limitations, including the high number of vaccine administrations and the fear of safety and effectiveness. In this regard, advanced vaccine products have been developed, like the combined vaccines, or are under development, such as nucleic acid vaccines (DNA and RNA), polymer-based vaccines, etc. Moreover, the possible use of traditional, like aluminium hydroxide and aluminium phosphate, or innovative adjuvants, like monophosphoryl lipid A, polysaccharides and nanoparticulate system, may further increase vaccine effectiveness. This review article focuses on the combined vaccines, which, especially when they are associated with adjuvants, reduce the dosing frequency, and prolong the duration of action, thus providing better vaccine coverage. Marketed preparations, like Typhim Vi, Peda typh and Boostrix showed better vaccine coverage for diseases like typhoid, tetanus, diphtheria and acellular pertussis. The future aspect for the development of combined vaccines will protect not only against infectious diseases but likely even against various infectious conditions, like pneumonia, meningococcal infection and respiratory syncytial virus infection.