Unmet needs in modern vaccinology: adjuvants to improve the immune response

Advances and challenges in the development of periodontitis vaccines: A comprehensive review

Periodontitis is a prevalent polymicrobial disease. It damages soft tissues and alveolar bone, and causes a significant public-health burden. Development of an advanced therapeutic approach and exploration of vaccines against periodontitis hold promise as potential treatment avenues. Clinical trials for a periodontitis vaccine are lacking. Therefore, it is crucial to address the urgent need for developing strategies to implement vaccines at the primary level of prevention in public health. A deep understanding of the principles and mechanisms of action of vaccines plays a crucial role in the successful development of vaccines and their clinical translation. This review aims to provide a comprehensive summary of potential directions for the development of highly efficacious periodontitis vaccines. In addition, we address the limitations of these endeavors and explore future possibilities for the development of an efficacious vaccine against periodontitis.

Immunological nanomaterials to combat cancer metastasis

Metastasis causes greater than 90% of cancer-associated deaths, presenting huge challenges for detection and efficient treatment of cancer due to its high heterogeneity and widespread dissemination to various organs. Therefore, it is imperative to combat cancer metastasis, which is the key to achieving complete cancer eradication. Immunotherapy as a systemic approach has shown promising potential to combat metastasis. However, current clinical immunotherapies are not effective for all patients or all types of cancer metastases owing to insufficient immune responses. In recent years, immunological nanomaterials with intrinsic immunogenicity or immunomodulatory agents with efficient loading have been shown to enhance immune responses to eliminate metastasis. In this review, we would like to summarize various types of immunological nanomaterials against metastasis. Moreover, this review will summarize a series of immunological nanomaterial-mediated immunotherapy strategies to combat metastasis, including immunogenic cell death, regulation of chemokines and cytokines, improving the immunosuppressive tumour microenvironment, activation of the STING pathway, enhancing cytotoxic natural killer cell activity, enhancing antigen presentation of dendritic cells, and enhancing chimeric antigen receptor T cell therapy. Furthermore, the synergistic anti-metastasis strategies based on the combinational use of immunotherapy and other therapeutic modalities will also be introduced. In addition, the nanomaterial-mediated imaging techniques (e.g., optical imaging, magnetic resonance imaging, computed tomography, photoacoustic imaging, surface-enhanced Raman scattering, radionuclide imaging, etc.) for detecting metastasis and monitoring anti-metastasis efficacy are also summarized. Finally, the current challenges and future prospects of immunological nanomaterial-based anti-metastasis are also elucidated with the intention to accelerate its clinical translation.

Vaccine adjuvants: current status, research and development, licensing, and future opportunities

Vaccines represent one of the most significant inventions in human history and have revolutionized global health. Generally, a vaccine functions by triggering the innate immune response and stimulating antigen-presenting cells, leading to a defensive adaptive immune response against a specific pathogen's antigen. As a key element, adjuvants are chemical materials often employed as additives to increase a vaccine's efficacy and immunogenicity. For over 90 years, adjuvants have been essential components in many human vaccines, improving their efficacy by enhancing, modulating, and prolonging the immune response. Here, we provide a timely and comprehensive review of the historical development and the current status of adjuvants, covering their classification, mechanisms of action, and roles in different vaccines. Additionally, we perform systematic analysis of the current licensing processes and highlights notable examples from clinical trials involving vaccine adjuvants. Looking ahead, we anticipate future trends in the field, including the development of new adjuvant formulations, the creation of innovative adjuvants, and their integration into the broader scope of systems vaccinology and vaccine delivery. The article posits that a deeper understanding of biochemistry, materials science, and vaccine immunology is crucial for advancing vaccine technology. Such advancements are expected to lead to the future development of more effective vaccines, capable of combating emerging infectious diseases and enhancing public health.

Protective Activity of Inactivated Rabies Vaccine Using Flagellin-Based Adjuvant

Rabies is a zoonotic disease with high lethality. Most human deaths are associated with the bites received from dogs and cats. Vaccination is the most effective method of preventing rabies disease in both animals and humans. In this study, the ability of an adjuvant based on recombinant Salmonella typhimurium flagellin to increase protective activity of the inactivated rabies vaccine in mice was evaluated. A series of inactivated dry culture vaccine for dogs and cats "Rabikan" (strain Shchelkovo-51) with addition of an adjuvant at various dilutions were used. The control preparation was a similar series of inactivated dry culture vaccine without an adjuvant. Protective activity of the vaccine preparations was evaluated by the NIH potency test, which is the most widely used and internationally recommended method for testing effectiveness of the inactivated rabies vaccines. The value of specific activity of the tested rabies vaccine when co-administered with the adjuvant was significantly higher (48.69 IU/ml) than that of the vaccine without the adjuvant (3.75 IU/ml). Thus, recombinant flagellin could be considered as an effective adjuvant in the composition of future vaccine preparations against rabies virus.

Construction and immunogenicity of Senecavirus A virus-like particle vaccine with adjuvant

Senecavirus A (SVA) is constantly associated with vesicular disease in pigs, and the clinical symptoms of pig infection with SVA are indistinguishable from other porcine vesicular diseases. Vaccine is one of the best methods to eliminate and control the spread of SVA. Virus-like particles (VLPs) can play important roles in prevention for infectious diseases. Here, the SVA VLPs was assembled by the baculovirus expression vector system, and the immunogenicity of the SVA VLPs mixed with different adjuvants were evaluated in mice and pigs. Two recombinant baculoviruses (rPFBD-VP1-VP3 and rPFBD-VP2-VP4) were constructed, which co-infected with Sf9 suspension cells to assemble SVA VLPs successfully. SVA VLPs mixed with ISA201 adjuvant and ISA201 +Poly(I:C) adjuvant produced higher levels of neutralizing antibody, specific antibody (total IgG, IgG1, IgG2a and IgG2b) and cytokines in the T cells. And there was no significant difference between SVA VLPs+ 201 group and SVA VLPs+Poly(I:C)+ 201 group. Pigs immunized with high dose of SVA VLPs mixed with ISA201 adjuvant could produce higher titers of neutralizing antibody and SVA-specific antibody. Furthermore, the protection rates of SVA VLPs-H and SVA VLPs-L were 100% and 80%, and the viral load of SVA VLPs-H group is the lowest in all SVA VLPs groups. It is the first time to develop the SVA VLPs using the baculovirus expression vector system, which may lay the foundation for the research and development of SVA vaccine.

Antitumoral effect of local injection of TLR-9 agonist emulsified in Lipiodol with systemic anti-PD-1 in a murine model of colorectal carcinoma

Introduction

Local treatments of cancer, including transarterial chemoembolization, could enhance responses to systemic immune checkpoint inhibitors such as anti-PD-1 antibodies. Lipiodol, a radiopaque oil, is widely used for transarterial chemoembolization as a tumor-targeting drug carrier and could be used in emulsion with immunomodulators. This study aimed at evaluating the antitumoral effect of intra-tumoral injection of Lipiodol-immunomodulator emulsions combined with systemic anti-PD-1 therapy in a murine model of colorectal carcinoma.

Method

Mice (male BALB/c) with anti-PD-1-resistant subcutaneous CT26 tumors were injected with immunomodulators, emulsified or not with Lipiodol (N=10-12/group).

Results

The TLR-9 agonist CpG displayed antitumor effects, while Poly I:C and QS21 did not. The Lipiodol-CpG emulsion appeared to be stable and maintained CpG within tumors for a longer time. Repeated intra-tumoral injections, combined with anti-PD-1, induced responses towards the tumor as well as to a distant metastatic-like nodule. This treatment was associated with an increase in proliferative CD8+ T cells and of IFN-γ expression, a decrease in proliferative regulatory T cells but also, surprisingly, an increase in myeloid derived suppressor cells.

Conclusions

Local administration of CpG emulsified with Lipiodol led to an effective antitumoral effect when combined to systemic anti-PD-1 therapy. Lipiodol, apart from its radiopaque properties, is an efficient drug-delivery system. The formulated oil-in-water emulsion allows efficient loading and control release of CpG, which induces favorable immune modifications in this murine tumor model.

Benefits of Combining Molecular Biology and Controlled Human Infection Model Methodologies in Advancing Vaccine Development

Infectious diseases continue to account for a significant portion of global deaths despite the use of vaccines for several centuries. Immunization programs around the world are a testament to the great success of multiple vaccines, yet there are still diseases without vaccines and others that require safer more effective ones. Addressing uncontrolled and emerging disease threats is restrained by the limitations and bottlenecks encountered with traditional vaccine development paradigms. Recent advances in modern molecular biology technologies have enhanced the interrogation of host pathogen interaction and deciphered complex pathways, thereby uncovering the myriad interplay of biological events that generate immune protection against foreign agents. Consequent to insights into the immune system, modern biology has been instrumental in the development and production of next generation 21st century vaccines. As these biological tools, commonly and collectively referred to as 'omics, became readily available, there has been a renewed consideration of Controlled Human Infection Models (CHIMs). Successful and reproducible CHIMs can complement modern molecular biology for the study of infectious diseases and development of effective vaccines in a regulated process that mitigates risk, cost, and time, with capacity to discern immune correlates of protection.

A new candidate epitope-based vaccine against PspA PhtD of Streptococcus pneumoniae: a computational experimental approach

Introduction

Pneumococcus is an important respiratory pathogen that is associated with high rates of death in newborn children and the elderly. Given the disadvantages of current polysaccharide-based vaccines, the most promising alternative for developing improved vaccines may be to use protein antigens with different roles in pneumococcus virulence. PspA and PhtD, highly immunogenic surface proteins expressed by almost all pneumococcal strains, are capable of eliciting protective immunity against lethal infections.

Methods

In this study using immunoinformatics approaches, we constructed one fusion construct (called PAD) by fusing the immunodominant regions of PspA from families 1 & 2 (PA) to the immunodominant regions of PhtD (PD). The objective of this project was to test the immunogenicity of the fusion protein PAD and to compare its protective activity against S. pneumoniae infection with PA or PD alone and a combination of PA and PD. The prediction of physicochemical properties, antigenicity, allergenicity, toxicity, and 3D-structure of the constructs, as well as molecular docking with HLA receptor and immune simulation were performed using computational tools. Finally, mice were immunized and the serum levels of antibodies/cytokines and functionality of antibodies in vitro were evaluated after immunization. The mice survival rates and decrease of bacterial loads in the blood/spleen were examined following the challenge.

Results

The computational analyses indicated the proposed constructs could be antigenic, non-allergenic, non-toxic, soluble and able to elicit robust immune responses. The results of actual animal experiments revealed the candidate vaccines could induce the mice to produce high levels of antibodies and cytokines. The complement-mediated bactericidal activity of antibodies was confirmed and the antibodies provided favorable survival in immunized mice after bacterial challenge. In general, the experimental results verified the immunoinformatics studies.

Conclusion

For the first time this report presents novel peptide-based vaccine candidates consisting of immunodominant regions of PspA and PhtD antigens. The obtained findings confirmed that the fusion formulation could be relatively more efficient than the individual and combination formulations. The results propose that the fusion protein alone could be used as a serotype-independent pneumococcal vaccine or as an effective partner protein for a conjugate polysaccharide vaccine.

Advances in Cancer Vaccine Research

The use of cancer vaccines is considered a promising therapeutic strategy in clinical oncology, which is achieved by stimulating antitumor immunity with tumor antigens delivered in the form of cells, peptides, viruses, and nucleic acids. The ideal cancer vaccine has many advantages, including low toxicity, specificity, and induction of persistent immune memory to overcome tumor heterogeneity and reverse the immunosuppressive microenvironment. Many therapeutic vaccines have entered clinical trials for a variety of cancers, including melanoma, breast cancer, lung cancer, and others. However, many challenges, including single antigen targeting, weak immunogenicity, off-target effects, and impaired immune response, have hindered their broad clinical translation. In this review, we introduce the principle of action, components (including antigens and adjuvants), and classification (according to applicable objects and preparation methods) of cancer vaccines, summarize the delivery methods of cancer vaccines, and review the clinical and theoretical research progress of cancer vaccines. We also present new insights into cancer vaccine technologies, platforms, and applications as well as an understanding of potential next-generation preventive and therapeutic vaccine technologies, providing a broader perspective for future vaccine design.

Bio-Inspired Nanomaterials for Micro/Nanodevices: A New Era in Biomedical Applications

Exploring bio-inspired nanomaterials (BINMs) and incorporating them into micro/nanodevices represent a significant development in biomedical applications. Nanomaterials, engineered to imitate biological structures and processes, exhibit distinctive attributes such as exceptional biocompatibility, multifunctionality, and unparalleled versatility. The utilization of BINMs demonstrates significant potential in diverse domains of biomedical micro/nanodevices, encompassing biosensors, targeted drug delivery systems, and advanced tissue engineering constructs. This article thoroughly examines the development and distinctive attributes of various BINMs, including those originating from proteins, DNA, and biomimetic polymers. Significant attention is directed toward incorporating these entities into micro/nanodevices and the subsequent biomedical ramifications that arise. This review explores biomimicry's structure-function correlations. Synthesis mosaics include bioprocesses, biomolecules, and natural structures. These nanomaterials' interfaces use biomimetic functionalization and geometric adaptations, transforming drug delivery, nanobiosensing, bio-inspired organ-on-chip systems, cancer-on-chip models, wound healing dressing mats, and antimicrobial surfaces. It provides an in-depth analysis of the existing challenges and proposes prospective strategies to improve the efficiency, performance, and reliability of these devices. Furthermore, this study offers a forward-thinking viewpoint highlighting potential avenues for future exploration and advancement. The objective is to effectively utilize and maximize the application of BINMs in the progression of biomedical micro/nanodevices, thereby propelling this rapidly developing field toward its promising future.

Viral protein nanoparticles (Part 1): Pharmaceutical characteristics

Viral protein nanoparticles fill the gap between viruses and synthetic nanoparticles. Combining advantageous properties of both systems, they have revolutionized pharmaceutical research. Virus-like particles are characterized by a structure identical to viruses but lacking genetic material. Another type of viral protein nanoparticles, virosomes, are similar to liposomes but include viral spike proteins. Both systems are effective and safe vaccine candidates capable of overcoming the disadvantages of both traditional and subunit vaccines. Besides, their particulate structure, biocompatibility, and biodegradability make them good candidates as vectors for drug and gene delivery, and for diagnostic applications. In this review, we analyze viral protein nanoparticles from a pharmaceutical perspective and examine current research focused on their development process, from production to administration. Advances in synthesis, modification and formulation of viral protein nanoparticles are critical so that large-scale production of viral protein nanoparticle products becomes viable and affordable, which ultimately will increase their market penetration in the future. We will discuss their expression systems, modification strategies, formulation, biopharmaceutical properties, and biocompatibility.

Self-Adjuvanting Calcium-Phosphate-Coated Microcrystal-Based Vaccines Induce Pyroptosis in Human and Livestock Immune Cells

Successful vaccines require adjuvants able to activate the innate immune system, eliciting antigen-specific immune responses and B-cell-mediated antibody production. However, unwanted secondary effects and the lack of effectiveness of traditional adjuvants has prompted investigation into novel adjuvants in recent years. Protein-coated microcrystals modified with calcium phosphate (CaP-PCMCs) in which vaccine antigens are co-immobilised within amino acid crystals represent one of these promising self-adjuvanting vaccine delivery systems. CaP-PCMCs has been shown to enhance antigen-specific IgG responses in mouse models; however, the exact mechanism of action of these microcrystals is currently unclear. Here, we set out to investigate this mechanism by studying the interaction between CaP-PCMCs and mammalian immune cells in an in vitro system. Incubation of cells with CaP-PCMCs induced rapid pyroptosis of peripheral blood mononuclear cells and monocyte-derived dendritic cells from cattle, sheep and humans, which was accompanied by the release of interleukin-1β and the activation of Caspase-1. We show that this pyroptotic event was cell-CaP-PCMCs contact dependent, and neither soluble calcium nor microcrystals without CaP (soluble PCMCs) induced pyroptosis. Our results corroborate CaP-PCMCs as a promising delivery system for vaccine antigens, showing great potential for subunit vaccines where the enhancement or find tuning of adaptive immunity is required.

Nanoparticle-Based Adjuvants and Delivery Systems for Modern Vaccines

Ever since the development of the first vaccine, vaccination has had the great impact on global health, leading to the decrease in the burden of numerous infectious diseases. However, there is a constant need to improve existing vaccines and develop new vaccination strategies and vaccine platforms that induce a broader immune response compared to traditional vaccines. Modern vaccines tend to rely on certain nanotechnology platforms but are still expected to be readily available and easy for large-scale manufacturing and to induce a durable immune response. In this review, we present an overview of the most promising nanoadjuvants and nanoparticulate delivery systems and discuss their benefits from tehchnological and immunological standpoints as well as their objective drawbacks and possible side effects. The presented nano alums, silica and clay nanoparticles, nanoemulsions, adenoviral-vectored systems, adeno-associated viral vectors, vesicular stomatitis viral vectors, lentiviral vectors, virus-like particles (including bacteriophage-based ones) and virosomes indicate that vaccine developers can now choose different adjuvants and/or delivery systems as per the requirement, specific to combatting different infectious diseases.

Dietary intervention with functional foods modulating gut microbiota for improving the efficacy of COVID-19 vaccines

Dysbiosis of the gut microbiota with aging contributes to a reduction in important cross-feeding bacterial reactions in the gut and immunosenescence, which could contribute to a decrease in vaccine efficacy. Fever, cough, and fatigue are the main signs of coronavirus disease 2019 (COVID-19); however, some patients with COVID-19 present with gastrointestinal symptoms. COVID-19 vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is one of the best measures to reduce SARS-CoV-2 infection rates and the severity of COVID-19. The immunogenicity of COVID-19 vaccines is influenced by the composition of the gut microbiota, and the immune response to COVID-19 vaccines decreases with age. In this review, we discuss gut microbiota dysbiosis and immunosenescence in the older adults, the role of gut microbiota in improving the efficacy of COVID-19 vaccines, and dietary interventions to improve the efficacy of COVID-19 vaccines in the older adults.

Synthesis and Biological Evaluation of Trehalose-based Bi-aryl Derivatives as C-type Lectin Ligands

The identification of Mincle as the C-type lectin receptor on innate immune cells responsible for binding TDM and the realization that this receptor could be key to productive vaccines for mycobacterial infection has raised interest in the development of synthetic Mincle ligands as novel adjuvants. We recently reported on the synthesis and evaluation of Brartemicin analog UM-1024 that demonstrated Mincle agonist activity, exhibiting potent Th1/Th17 adjuvant activity that was greater than that of trehalose dibehenate (TDB). Our pursuit to understand Mincle/ligand relationships and improve the pharmacologic properties of the ligands has expanded and continues to reveal new and exciting structure activity relationships. Herein we report the synthesis of novel bi-aryl trehalose derivatives in good to excellent yields. These compounds were evaluated for their ability to engage the human Mincle receptor and tested for the induction of cytokines from human peripheral blood mononuclear cells. A preliminary structure-activity relationship (SAR) of these novel bi-aryl derivatives revealed that bi-aryl trehalose ligand 3D showed relatively high potency in cytokine production in comparison to trehalose glycolipid adjuvant TDB and the natural ligand TDM and induced dose-dependent, Mincle selective stimulation in hMincle HEK reporter cells. Also, through computational studies, we provide an insight into the potential mode of binding of 6,6'-Biaryl trehalose compounds on human Mincle receptor.

Nonclinical safety assessments of a novel synthetic toll-like receptor 4 agonist and saponin based adjuvant

A full nonclinical safety package was performed to support the clinical use of SPA14, a novel liposome-based vaccine adjuvant containing the synthetic toll-like receptor 4 agonist E6020 and saponin QS21. E6020 and QS21 were tested negative for their potential genotoxic effects in Ames, micronucleus, or mouse-lymphoma TK (thymidine kinase) assay. To evaluate the potential local and systemic effects of SPA14, two toxicity studies were performed in rabbits. In the first dose range finding toxicity study, rabbits received two intramuscular injections of SPA14 at increasing doses of E6020 combined with two antigens, a control (saline), the two antigens alone, or the antigens adjuvanted with a liposome-based adjuvant AS01B. No systemic toxicity was detected, supporting the dose of 5 μg of E6020 for the subsequent pivotal study. In the second repeated dose toxicity study, rabbits received four intramuscular injections of SPA14 alone, a control (saline), SPA14 combined with two antigens, the two antigens alone, or the antigens combined with AF03 adjuvant, which is a squalene-based emulsion. SPA14 alone or in combination with the antigens was well tolerated and did not cause any systemic toxicity. Finally, two safety pharmacology studies were conducted to assess potential cardiovascular and respiratory effects of E6020 and SPA14 in conscious telemetered cynomolgus monkeys and beagle dogs, respectively. One subcutaneous injection of E6020 in monkeys and one intramuscular injection of SPA14 in dogs had no consequences on respiratory and cardiovascular functions. Altogether these results support the clinical development of SPA14.

Chemical Synthesis and Immunomodulatory Functions of Bacterial Lipid As

Lipopolysaccharide (LPS), a cell surface component of Gram-negative bacteria, and its active principle, lipid A, have immunostimulatory properties and thus potential to act as adjuvants. However, canonical LPS acts as an endotoxin by hyperstimulating the immune response. Therefore, it is necessary to structurally modify LPS and lipid A to minimize toxicity while maintaining adjuvant effects for use as vaccine adjuvants. Various studies have focused on the chemical synthetic method of lipid As and their structure-activity relationship, which are reviewed in this chapter.

Advancement and Applications of Platelet-inspired Nanoparticles: A Paradigm for Cancer Targeting

Platelet-inspired nanoparticles have ignited the possibility of new opportunities for producing similar biological particulates, such as structural cellular and vesicular components, as well as various viral forms, to improve biocompatible features that could improve the nature of biocompatible elements and enhance therapeutic efficacy. The simplicity and more effortless adaptability of such biomimetic techniques uplift the delivery of the carriers laden with cellular structures, which has created varied opportunities and scope of merits like; prolongation in circulation and alleviating immunogenicity improvement of the site-specific active targeting. Platelet-inspired nanoparticles or medicines are the most recent nanotechnology-based drug targeting systems used mainly to treat blood-related disorders, tumors, and cancer. The present review encompasses the current approach of platelet-inspired nanoparticles or medicines that have boosted the scientific community from versatile fields to advance biomedical sciences. Surprisingly, this knowledge has streamlined to development of newer diagnostic methods, imaging techniques, and novel nanocarriers, which might further help in the treatment protocol of the various diseased conditions. The review primarily focuses on the novel advancements and recent patents in nanoscience and nanomedicine that could be streamlined in the future for the management of progressive cancers and tumor targeting. Rigorous technological advancements like biomimetic stem cells, pH-sensitive drug delivery of nanoparticles, DNA origami devices, virosomes, nano cells like exosomes mimicking nanovesicles, DNA nanorobots, microbots, etc., can be implemented effectively for target-specific drug delivery.

Structure-Activity Relationship Study of Momordica Saponin II Derivatives as Vaccine Adjuvants

VSA-2 is a recently developed semisynthetic saponin immunostimulant. It is prepared by incorporating a terminal-functionalized side chain to the branched trisaccharide domain at the C3 position of Momordica saponin II (MS II) isolated from the seeds of perennial Momordica cochinchinensis Spreng. Direct comparison of VSA-2 and the clinically proven saponin adjuvant QS-21 shows that VSA-2 is comparable to QS-21 in enhancing humoral and cellular immune responses. Structure-activity relationship studies show that structural changes in the side chain have a significant impact on saponins' adjuvant activity. However, with the VSA-2 molecular framework intact, the new VSA-2 analogues with various substitution(s) at the terminal benzyl group of the side chain retain the ability of potentiating antigen-specific humoral and cellular responses.

Immunological evaluation of recombination PRRSV GP3 and GP5 DNA vaccines in vivo

The porcine reproductive and respiratory syndrome virus (PRRSV) is a threat to the health of pigs worldwide, but commercially available vaccines offer limited protection against PRRSV infection. It is necessary to develop a more effective DNA vaccine. The immunological effects of DNA vaccines with three adjuvants were examined in pigs (Susscrofa domestica) challenged with PRRSV. These DNA vaccines, which encoded PRRSV GP3 and GP5, were formulated with A1, A2, and A3. Serum specific and neutralizing antibodies, IL-4, IFN-γ, IL-2, IL-10, CD4⁺ and CD8⁺T-lymphocytes, health status, histopathology, and viral loads were determined. The results showed that the use of adjuvant A3 led to higher levels of neutralizing antibodies and a lower viral load in pigs compared to the other adjuvants. The neutralizing antibody titers of the pVAX-GP35+A1 and pVAX-GP35+A3 groups reached a peak of 1:19 at 35 dpi. The maximum concentration of IL-4 was 136.77 pg/mL in the pVAX-GP35+A3 group. At 35 dpi, the IFN-γ concentration in the pVAX-GP35+A1 group was 227.4 pg/mL. pVAX-GP35+A3 group shows the highest IL-2 and IL-10 expression to the peak of 597.6 pg/mL and 189.1 pg/mL, respectively. We found a formulation demonstrated beneficial immune outcomes. This study provides an alternative vaccine to protect pigs from PRRSV.

Biomimetic Nanovesicles—Sources, Design, Production Methods, and Applications

Despite all the progress in the field of liposomes and nanoparticles for applications as drug and gene delivery systems, the specific targeting and immune system escape capabilities of these systems are still limited. Biomimetic nanovesicles emerged as a strategy to overcome these and other limitations associated with synthetic carriers, such as short circulation time, cytotoxicity, and difficulty in crossing biological barriers, since many of the desirable abilities of drug delivery systems are innate characteristics of biological vesicles. Thus, the question arises: would biomimetic nanovesicles be responsible for addressing these advances? It is currently known that biomimetic nanovesicles (BNV) can combine the intrinsic advantages of natural materials with the well-known production methods and controllability of synthetic systems. Besides, the development of the biotechnology and nanotechnology fields has provided a better understanding of the functionalities of biological vesicles and the means for the design and production of biomimetic nanovesicles (BNV). Based on this, this work will focus on tracking the main research on biomimetic nanovesicles (BNV) applied as drug and gene delivery systems, and for vaccines applications. In addition, it will describe the different sources of natural vesicles, the technical perspectives on obtaining them, and the possibility of their hybridization with synthetic liposomes.

Adjuvant Effects of a New Saponin Analog VSA-1 on Enhancing Homologous and Heterosubtypic Protection by Influenza Virus Vaccination

Adjuvants can increase the magnitude and durability of the immune response generated by the vaccine antigen. Aluminum salts (Alum) remain the main adjuvant licensed for human use. A few new adjuvants have been licensed for use in human vaccines since the 1990s. QS-21, a mixture of saponin compounds, was included in the AS01-adjuvanted Shingrix vaccine. Here, we investigated the adjuvant effects of VSA-1, a newly developed semisynthetic analog of QS-21, on promoting protection in mice after vaccination with the inactivated split virus vaccine. The adjuvant effects of VSA-1 on improving vaccine efficacy after prime immunization were evident as shown by significantly higher levels of hemagglutination-inhibiting antibody titers and enhanced homologous protection compared to those by QS-21 and Alum adjuvants. The adjuvant effects of VSA-1 on enhancing heterosubtypic protection after two doses of adjuvanted vaccination were comparable to those of QS-21. T cell immunity played an important role in conferring cross-protection by VSA-1-adjuvanted vaccination. Overall, the findings in this study suggest that VSA-1 exhibits desirable adjuvant properties and a unique pattern of innate and adaptive immune responses, contributing to improved homologous and heterosubtypic protection by inactivated split influenza vaccination in mice.

Biopolymers and Osmolytes - A Focus towards the Prospects of Stability and Adjuvanticity of Vaccines

‘New-Gen Vaccines’ are grabbing the attention of scientists as they are much suitable for an immune-compromised group of individuals as well as infants. The major drawbacks of these vaccines are lower immunogenicity and instability. The need for a convenient and safe adjuvant is still under exploration. On the other hand, thermal instability leads to the inactivation of the vaccine and becomes detrimental in many cases. Thus, there is a need to incorporate new kinds of excipients into vaccine formulation to enhance the potency/immunogenicity of vaccine antigens and also act as stabilizers. A limited or single excipient in providing the required dual-activity is vital to break the stereotypical usage of the well-entrenched adverse ingredients. In the proposed review, the efficiency of naturally occurring biocompatible carbohydrate polymers and osmolytes and their ‘dual-role’ is briefed. In addition, the information on the possible mechanisms of action of carbohydrate polymers in vaccines as adjuvants and stabilizers are also discussed.

Protective response mediated by immunization with recombinant proteins in a murine model of toxocariasis and canine infection by Toxocara canis

Toxocariasis is a neglected parasitic zoonosis of global importance. The development of a formulation that can be used as a vaccine would help the definitive control of the infection. Preclinical studies selected two recombinant T. canis proteins (rTcVcan and rTcCad) which significantly protected mice against larval migration. In the present work, these proteins plus three adjuvants (Alhydrogel®, PAM3CSK4®, and Quil-A®) were used to immunize mice against toxocariasis; blood samples were collected three times to measure IgG (total, IgG1, IgG2a), IgA, and IgE via indirect ELISA. Cytokines (IL-5, TNF-α, and IL-10) were measured in splenocytes supernatant, and T. canis larvae were quantified in tissues. The best protein + adjuvant pair found (rTVcan + QuialA®) was then used to immunize T. canis-free puppies (n = 18) that were experimentally infected with T. canis and T. canis naturally-infected puppies (n = 6). Immunoglobulin (IgA, IgE, IgG, IgG1, and IgG2a), parasite load (eggs in feces), number of expelled adults and eggs extracted from the female uterus, and their fertility percentages were analyzed. In mice, it was observed a highly significant reduction (73%) of tissue larvae, a mixed cytokine profile (Th₁/Th₂), and anti-T. canis antibody titers (IgG, IgG1, IgG2a) using rTVcan + QuialA® mix. In canines, rTVcan + QuialA® promoted reduction in the parasite eggs in feces (95%) and eggs reduction obtained from the uteri of pharmacologically expelled adult females (58.38%). In our knowledge this is the first canine clinical trial of a vaccine with T. canis recombinant proteins. The formulation used has been shown to efficiently stimulate the production of antibodies against infection by T. canis. In the canine, a significant reduction in the number of eggs expelled by the experimental animals that received the formulation prophylactically was evidenced. Future tests should be developed to evaluate the duration of the protective effect and analyze other immune pathways that could be stimulated by the formulation used.

Combinatorial Therapeutic Approaches with Nanomaterial-Based Photodynamic Cancer Therapy

Photodynamic therapy (PDT), in which a light source is used in combination with a photosensitizer to induce local cell death, has shown great promise in therapeutically targeting primary tumors with negligible toxicity and minimal invasiveness. However, numerous studies have shown that noninvasive PDT alone is not sufficient to completely ablate tumors in deep tissues, due to its inherent shortcomings. Therefore, depending on the characteristics and type of tumor, PDT can be combined with surgery, radiotherapy, immunomodulators, chemotherapy, and/or targeted therapy, preferably in a patient-tailored manner. Nanoparticles are attractive delivery vehicles that can overcome the shortcomings of traditional photosensitizers, as well as enable the codelivery of multiple therapeutic drugs in a spatiotemporally controlled manner. Nanotechnology-based combination strategies have provided inspiration to improve the anticancer effects of PDT. Here, we briefly introduce the mechanism of PDT and summarize the photosensitizers that have been tested preclinically for various cancer types and clinically approved for cancer treatment. Moreover, we discuss the current challenges facing the combination of PDT and multiple cancer treatment options, and we highlight the opportunities of nanoparticle-based PDT in cancer therapies.

Supramolecular Nanostructures for Vaccines

Although this is an era of pandemics and many devastating diseases, this is also a time when bionanotechnology flourishes, illuminating a multidisciplinary field where vaccines are quickly becoming a balsam and a prevention against insidious plagues. In this work, we tried to gain and also give a deeper understanding on nanovaccines and their way of acting to prevent or cure cancer, infectious diseases, and diseases caused by parasites. Major nanoadjuvants and nanovaccines are temptatively exemplified trying to contextualize our own work and its relative importance to the field. The main properties for novel adjuvants seem to be the nanosize, the cationic character, and the biocompatibility, even if it is achieved in a low dose-dependent manner.

Head and Neck Squamous Cell Carcinoma: Risk Factors, Molecular Alterations, Immunology and Peptide Vaccines

Head and neck squamous cell carcinoma (HNSCC) arises from the epithelial lining of the oral cavity, hypopharynx, oropharynx, and larynx. There are several potential risk factors that cause the generation of HNSCC, including cigarette smoking, alcohol consumption, betel quid chewing, inadequate nutrition, poor oral hygiene, HPV and Epstein–Barr virus, and Candida albicans infections. HNSCC has causative links to both environmental factors and genetic mutations, with the latter playing a more critical role in cancer progression. These molecular changes to epithelial cells include the inactivation of cancer suppressor genes and proto-oncogenes overexpression, resulting in tumour cell proliferation and distant metastasis. HNSCC patients have impaired dendritic cell (DC) and natural killer (NK) cell functions, increased production of higher immune-suppressive molecules, loss of regulatory T cells and co-stimulatory molecules and major histocompatibility complex (MHC) class Ι molecules, lower number of lymphocyte subsets, and a poor response to antigen-presenting cells. At present, the standard treatment modalities for HNSCC patients include surgery, chemotherapy and radiotherapy, and combinatorial therapy. Despite advances in the development of novel treatment modalities over the last few decades, survival rates of HNSCC patients have not increased. To establish effective immunotherapies, a greater understanding of interactions between the immune system and HNSCC is required, and there is a particular need to develop novel therapeutic options. A therapeutic cancer vaccine has been proposed as a promising method to improve outcome by inducing a powerful adaptive immune response that leads to cancer cell elimination. Compared with other vaccines, peptide cancer vaccines are more robust and specific. In the past few years, there have been remarkable achievements in peptide-based vaccines for HNSCC patients. Here, we summarize the latest molecular alterations in HNSCC, explore the immune response to HNSCC, and discuss the latest developments in peptide-based cancer vaccine strategies. This review highlights areas for valuable future research focusing on peptide-based cancer vaccines.

Brief on Recent Application of Liposomal Vaccines for Lower Respiratory Tract Viral Infections: From Influenza to COVID-19 Vaccines

Vaccination is the most effective means of preventing infectious diseases and saving lives. Modern biotechnology largely enabled vaccine development. In the meantime, recent advances in pharmaceutical technology have resulted in the emergence of nanoparticles that are extensively investigated as promising miniaturized drug delivery systems. Scientists are particularly interested in liposomes as an important carrier for vaccine development. Wide acceptability of liposomes lies in their flexibility and versatility. Due to their unique vesicular structure with alternating aqueous and lipid compartments, liposomes can enclose both hydrophilic and lipophilic compounds, including antigens. Liposome composition can be tailored to obtain the desired immune response and adjuvant characteristics. During the current pandemic of COVID-19, many liposome-based vaccines have been developed with great success. This review covers a liposome-based vaccine designed particularly to combat viral infection of the lower respiratory tract (LRT), i.e., infection of the lung, specifically in the lower airways. Viruses such as influenza, respiratory syncytial virus (RSV), severe acute respiratory syndrome (SARS-CoV-1 and SARS-CoV-2) are common causes of LRT infections, hence this review mainly focuses on this category of viruses.

Inhalable polymeric micro and nano-immunoadjuvants for developing therapeutic vaccines in the treatment of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is a leading cause of death in millions of cancer patients. Lack of diagnosis at an early stage in addition to no specific guidelines for its treatment, and a higher rate of treatment-related toxicity further deteriorate the conditions. Current therapies encompass surgery, chemotherapy, radiation therapy, and immunotherapy according to the pattern and the stage of lung cancer. Among all, with a longlasting therapeutic action, reduced side-effects, and a higher rate of survival, therapeutic cancer vaccine is a new, improved strategy for treating NSCLC. Immunoadjuvants are usually incorporated into the therapeutic vaccines to shield the antigen against environmental and physiological harsh conditions in addition to boosting the immune potential. Conventional immunoadjuvants are often associated with an inadequate cellular response, poor target specificity, and low antigen load. Recently, inhalable polymeric nano/micro immunoadjuvants have exhibited immense potential in the development of therapeutic vaccines for the treatment of NSCLC with improved mucosal immunization. The development of polymeric micro/nano immunoadjuvants brought a new era for vaccines with increased strength and efficiency. Therefore, in the present review, we explained the potential application of micro/nano immunoadjuvants for augmenting the stability and efficacy of inhalable vaccines in the treatment of NSCLC. In addition, the role of biodegradable, biocompatible, and non-toxic polymers has also been discussed with case studies.

Synthesis, LC-MS/MS analysis, and biological evaluation of two vaccine candidates against ticks based on the antigenic P0 peptide from R. sanguineus linked to the p64K carrier protein from Neisseria meningitidis

A peptide from the P0 acidic ribosomal protein (pP0) of ticks conjugated to keyhole limpet hemocyanin from Megathura crenulata has shown to be effective against different tick species when used in host vaccination. Turning this peptide into a commercial anti-tick vaccine will depend on finding the appropriate, technically and economically feasible way to present it to the host immune system. Two conjugates (p64K-Cys¹pP0 and p64K-βAla¹pP0) were synthesized using the p64K carrier protein from Neisseria meningitidis produced in Escherichia coli, the same cross-linking reagent, and two analogues of pP0. The SDS-PAGE analysis of p64K-Cys¹pP0 showed a heterogeneous conjugate compared to p64K-βAla¹pP0 that was detected as a protein band at 91kDa. The pP0/p64K ratio determined by MALDI-MS for p64K-Cys¹pP0 ranged from 1 to 8, being 3-5 the predominant ratio, while in the case of p64K-βAla¹pP0 this ratio was 5-7. Cys¹pP0 was partially linked to 35 out of 39 Lys residues and the N-terminal end, while βAla¹pP0 was mostly linked to the six free cysteine residues, to the N-terminal end, and, in a lesser extent, to Lys residues. The assignment of the conjugation sites and side reactions were based on the identification of type 2 peptides. Rabbit immunizations showed the best anti-pP0 titers and the highest efficacy against Rhipicephalus sanguineus ticks when the p64K-Cys¹pP0 was used as vaccine antigen. The presence of high molecular mass aggregates observed in the SDS-PAGE analysis of p64K-Cys¹pP0 could be responsible for a better immune response against pP0 and consequently for its better efficacy as an anti-tick vaccine.

Montanide™ ISA 763A VG and ISA 761 VG induce different immune pathway responses in rainbow trout (Oncorhynchus mykiss) when used as adjuvant for an Aeromonas salmonicida bacterin

Adjuvants are the helper substances that increase vaccine efficacy by enhancing the potency and longevity of specific immune responses to antigens. Most existing fish vaccines are presented in the form of oil-based emulsions delivered by intraperitoneal injection. The characterization of their mode of action is a valuable aid to future vaccine development, particularly for the potential identification and stimulation of specific immunological pathways related to the desired protective response. This study characterized the expression of selected immune-related genes in the peritoneal cavity, head kidney and spleen following the administration of two adjuvanted-bacterial vaccines thought to induce humoral (Montanide™ ISA 763A VG) or humoral and cell mediated (Montanide™ ISA 761 VG) immune responses, to determine if differences in responsiveness are readily apparent. The most informative site was the spleen, where Montanide™ ISA 763A VG + bacterin gave rise to upregulation of genes driving T-cell/lymphoid responses, namely IL-2, IL-15 and IL-21. This combined with upregulation of IFNγ1 and IFNγ2, IL-4/13B2, p35A1 and p40 (B1 and C) indicated that the induction of Th1 and possibly Th2 immunity was occurring in fish vaccinated with this adjuvant. Perhaps the most intriguing finding was the lack of a detectable Th1 response in fish given Montanide™ ISA 761 VG + bacterin, suggesting some other arm of the immune system is activated to give protection. Whatever the reason for the different responses detected, it is clear from the present study that the adjuvant used has a major impact on the responses elicited. Since these differences are readily detectable it allows, in principle, their use to help select the most appropriate adjuvants for inclusion into fish vaccines, where the type of response elicited may need to be tailored to a particular pathogen to confer protection.

Incomplete Freund's adjuvant reduces arginase and enhances Th1 dominance, TLR signaling and CD40 ligand expression in the vaccine site microenvironment

Background

Immunogenicity of cancer vaccines is impacted by adjuvants and schedule, but systematic assessments of their effects have not been performed. Montanide ISA-51, an incomplete Freund’s adjuvant (IFA), is used in many vaccine trials, but concerns have been raised about negative effects in murine studies. We found in humans that IFA enhances systemic immune responses and that repeat vaccination at one site (same site vaccination (SSV)) creates tertiary lymphoid structures (TLS) in the vaccine site microenvironment (VSME). We hypothesized that vaccination with peptides+IFA+pICLC or SSV×3 with peptides in IFA would create an immunogenic milieu locally at the VSME, with activated dendritic cells (DC), TLS-associated chemokines and a Th1-dominant VSME.

Methods

Biopsies of the VSME were obtained from participants on two clinical trials who were immunized with multiple melanoma peptides (MELITAC 12.1) in adjuvants comprising IFA and/or the TLR3-agonist pICLC. Biopsies were obtained either a week after one vaccine or a week after SSV×3. Controls included normal skin and skin injected with IFA without peptides. Gene expression analysis was performed by RNAseq.

Results

VSME samples were evaluated from 27 patients. One vaccine with peptides in pICLC+IFA enhanced expression of CD80, CD83, CD86 (p<0.01), CD40 and CD40L (p<0.0001) over normal skin; these effects were significantly enhanced for SSV with peptides+IFA. Vaccines containing pICLC increased expression of TBX21 (T-bet) but did not decrease GATA3 over normal skin, whereas SSV with peptides in IFA dramatically enhanced TBX21 and decreased GATA3, with high expression of IFNγ and STAT1. SSV with peptides in IFA also reduced arginase-1 (ARG1) expression and enhanced expression of TLR adapter molecules TICAM-1 (TRIF) and MYD88. Furthermore, SSV with IFA and peptides also enhanced expression of chemokines associated with TLS formation.

Conclusions

These findings suggest that SSV with peptides in IFA enhances CD40L expression by CD4 T cells, supports a Th1 microenvironment, with accumulation of activated and mature DC. Increased expression of TLR adaptor proteins after SSV with peptides in IFA might implicate effects of the skin microbiome. Reduced ARG1 may reflect diminished suppressive myeloid activity in the VSME.

Trial registration number

(NCT00705640, NCT01585350).

A brief, highly selective history of acute phase proteins as indicators of infection, inflammation and injury

There is an array of plasma protein alterations that occur in a wide variety of species, including humans in response to trauma, inflammation and infections, seemingly irrespective of etiologic agent. In numerous species, these plasma proteins are part of the innate immune response. In addition, it appears that a number of the plasma proteins in this array can be predictive of morbidity and/or mortality. We propose that based on historic use, selected acute phase proteins should be included in ongoing and future non-clinical and clinical studies to help us better understand disease progression in chronic, as well as acute diseases. In addition to assess if there is a relationship between vaccine-induced inflammation and degree of protection from live, attenuated or synthetic vaccines.

Design of Trehalose-Based Amide/Sulfonamide C-type Lectin Receptor Signaling Compounds

Mincle agonists have been shown to induce inflammatory cytokine production, such as tumor necrosis factor-alpha (TNF) and promote the development of a Th1/Th17 immune response that might be crucial to development of effective vaccination against pathogens such as Mycobacterium tuberculosis. As an expansion of our previous work, a library of 6,6'-amide and sulfonamide α,α-d-trehalose compounds with various substituents on the aromatic ring was synthesized efficiently in good to excellent yields. These compounds were evaluated for their ability to activate the human C-type lectin receptor Mincle by the induction of cytokines from human peripheral blood mononuclear cells. A preliminary structure-activity relationship (SAR) of these novel trehalose diamides and sulfonamides revealed that aryl amide-linked trehalose compounds demonstrated improved activity and relatively high potency cytokine production compared to the Mincle ligand trehalose dibehenate adjuvant (TDB) and the natural ligand trehalose dimycolate (TDM) inducing dose-dependent and human-Mincle-specific stimulation in a HEK reporter cell line.

Natural and Synthetic Saponins as Vaccine Adjuvants

Saponin adjuvants have been extensively studied for their use in veterinary and human vaccines. Among them, QS-21 stands out owing to its unique profile of immunostimulating activity, inducing a balanced Th1/Th2 immunity, which is valuable to a broad scope of applications in combating various microbial pathogens, cancers, and other diseases. It has recently been approved for use in human vaccines as a key component of combination adjuvants, e.g., AS01b in Shingrix^® for herpes zoster. Despite its usefulness in research and clinic, the cellular and molecular mechanisms of QS-21 and other saponin adjuvants are poorly understood. Extensive efforts have been devoted to studies for understanding the mechanisms of QS-21 in different formulations and in different combinations with other adjuvants, and to medicinal chemistry studies for gaining mechanistic insights and development of practical alternatives to QS-21 that can circumvent its inherent drawbacks. In this review, we briefly summarize the current understandings of the mechanism underlying QS-21’s adjuvanticity and the encouraging results from recent structure-activity-relationship (SAR) studies.

The Search of a Malaria Vaccine: The Time for Modified Immuno-Potentiating Probes

Malaria is a deadly disease that takes the lives of more than 420,000 people a year and is responsible for more than 229 million clinical cases globally. In 2019, 95% of malaria morbidity occurred in African countries. The development of a highly protective vaccine is an urgent task that remains to be solved. Many vaccine candidates have been developed, from the use of the entire attenuated and irradiated pre-erythrocytic parasite forms (or recombinantly expressed antigens thereof) to synthetic candidates formulated in a variety of adjuvants and delivery systems, however these have unfortunately proven a limited efficacy. At present, some vaccine candidates are finishing safety and protective efficacy trials, such as the PfSPZ and the RTS,S/AS01 which are being introduced in Africa. We propose a strategy for introducing non-natural elements into target antigens representing key epitopes of Plasmodium spp. Accordingly, chemical strategies and knowledge of host immunity to Plasmodium spp. have served as the basis. Evidence is obtained after being tested in experimental rodent models for malaria infection and recognized for human sera from malaria-endemic regions. This encourages us to propose such an immune-potentiating strategy to be further considered in the search for new vaccine candidates.

Lipid Nanoparticles as Delivery Systems for RNA-Based Vaccines

There has been increased interest in the development of RNA-based vaccines for protection against various infectious diseases and also for cancer immunotherapies. Rapid and cost-effective manufacturing methods in addition to potent immune responses observed in preclinical and clinical studies have made mRNA-based vaccines promising alternatives to conventional vaccine technologies. However, efficient delivery of these vaccines requires that the mRNA be protected against extracellular degradation. Lipid nanoparticles (LNPs) have been extensively studied as non-viral vectors for the delivery of mRNA to target cells because of their relatively easy and scalable manufacturing processes. This review highlights key advances in the development of LNPs and reviews the application of mRNA-based vaccines formulated in LNPs for use against infectious diseases and cancer.

Heat Shock Proteins 90 kDa: Immunomodulators and Adjuvants in Vaccine Design Against Infectious Diseases

Heat shock proteins 90 kDa (Hsp90s) were originally identified as stress-responsive proteins and described to participate in several homeostatic processes. Additionally, extracellular Hsp90s have the ability to bind to surface receptors and activate cellular functions related to immune response (cytokine secretion, cell maturation, and antigen presentation), making them very attractive to be studied as immunomodulators. In this context, Hsp90s are proposed as new adjuvants in the design of novel vaccine formulations that require the induction of a cell-mediated immune response to prevent infectious diseases. In this review, we summarized the adjuvant properties of Hsp90s when they are either alone, complexed, or fused to a peptide to add light to the knowledge of Hsp90s as carriers and adjuvants in the design of vaccines against infectious diseases. Besides, we also discuss the mechanisms by which Hsp90s activate and modulate professional antigen-presenting cells.

Polymeric Nanoparticle-Based Vaccine Adjuvants and Delivery Vehicles

As vaccine formulations have progressed from including live or attenuated strains of pathogenic components for enhanced safety, developing new adjuvants to more effectively generate adaptive immune responses has become necessary. In this context, polymeric nanoparticles have emerged as a promising platform with multiple advantages, including the dual capability of adjuvant and delivery vehicle, administration via multiple routes, induction of rapid and long-lived immunity, greater shelf-life at elevated temperatures, and enhanced patient compliance. This comprehensive review describes advances in nanoparticle-based vaccines (i.e., nanovaccines) with a particular focus on polymeric particles as adjuvants and delivery vehicles. Examples of the nanovaccine approach in respiratory infections, biodefense, and cancer are discussed.

Different kinetics of chicken interferon-alpha signalling transduction responses following immunization of broiler chickens with different Newcastle disease virus vaccines and infection with virulent genotype VIId strain

Newcastle disease virus (NDV) is a highly contagious and notifiable avian disease leading to grave economic losses in the poultry industry. Although the immune responses against NDV have been widely investigated, little is known regarding the virus interaction with the host innate immune responses. In this study, we tested the effect of different commercially applied Newcastle disease vaccines as well as virulent NDV genotype VIId on the expression pattern of the upstream regulator and downstream effector genes related to chicken interferon-alpha (chIFNα) signalling transduction pathway. Using quantitative real-time PCR analysis, mild transient induction of chIFNα-inducible genes was detected in bird spleen 72 h post-vaccination (hpv) with either live LaSota (respiratory) or VG/GA (enteric) strains. Vaccination with the enteric VG/GA strain led to stimulation of the investigated pathway as early as 24 hpv which continued up to 7 days in bird caecal tonsils. Subcutaneous injection with inactivated LaSota oil adjuvant-based vaccine led to continual stimulation of the investigated pathway up to 7 days post-vaccination (dpv). The recombinant herpesvirus of turkey (rHVT) - NDV vaccine led to remarkable stimulation of all the tested cytokines up to 17 dpv in comparison with LaSota and VG/GA NDV vaccines. Stronger but transient activation of all the tested cytokines was detected in spleens during the first 24 h post-challenge with virulent NDV (vNDV) which reduced gradually and diminished later due to the virus-induced lymphocytic depletion. This study will aid in the discovery of new approaches to control NDV.

Immune responses induced by inactivated porcine reproductive and respiratory syndrome virus (PRRSV) vaccine in neonatal pigs using different adjuvants

Vaccination of neonatal pigs could be supportive to prevent porcine reproductive and respiratory syndrome virus (PRRSV), which is an important porcine pathogen causing worldwide welfare and health problems in pigs of different age classes. However, neonatal immunity substantially differs to adults, thus different vaccines may be required in neonateal pigs. We examined if the immunogenicity and efficacy of inactivated PRRSV (iPRRSV) vaccines in neonatal pigs could be improved with adjuvants containing oil-in water (O/W) emulsions with or without Toll-like receptor (TLR) agonists and by altering the delivery route from intramuscular (i.m.) to the skin. Three-day-old PRRSV-naïve piglets (n = 54, divided in 6 groups) received a prime vaccination and a booster vaccination four weeks later. The vaccine formulations consisted of different O/W emulsions (Montanide™ ISA28RVG (ISA28)), a squalene in water emulsion (SWE) for i.m. or a Stable Emulsion (SE) with squalene for skin vaccination) and/or a mixture of TLR1/2, 7/8 and 9 agonists (TLRa) combined with iPRRSV strain 07V063. These vaccines were delivered either i.m. (ISA28, SWE, TLRa or SWE + TLRa) or into the skin (skiSE + TLRa) with dissolving microneedle (DMN)-patches. All animals received a challenge with homologous PRRSV three weeks after booster vaccination. Specific antibodies, IFN-γ production and viremia were measured at several time-points after vaccination and/or challenge, while lung pathology was studied at necropsy. After booster vaccination, only ISA28 induced a specific antibody response while a specific T-cell IFN-γ response was generated in the SWE group, that was lower for ISA28, and absent in the other groups. This suggests that prime vaccination in neonates induced a specific immune response after booster vaccination, dependent on the emulsion formulation, but not dependent on the presence of the TLRa or delivery route. Despite the measured immune responses none of the vaccines showed any efficacy. Further research focused on the early immune response in draining lymph nodes is needed to elucidate the potential of TLR agonists in vaccines for neonatal pigs.

Association of Bacillus toyonensis spores with alum improves bovine herpesvirus 5 subunit vaccine immune response in mice

Spores of the genus Bacillus are molecules capable of increasing the vaccine adjuvanticity. Bovine herpesvirus type 5 (BoHV-5) is responsible for meningoencephalitis that causes important economic losses in cattle. BoHV-5 glycoprotein D (gD) is a target of vaccine antigen and plays an important role in host cell penetration. The present study aimed to evaluate the adjuvanticity of Bacillus toyonensis (B.t) spores, live and heat-killed, associated with a vaccine formulated with aluminum hydroxide (alum) and the recombinant BoHV-5 glycoprotein D (rgD) in an experimental murine model. Six experimental groups of mice were subcutaneously vaccinated on day 0 and received a booster on day 21 of the experiment, with the following vaccine formulations: rgD (40 µg) + live spores (2 × 10⁹ CFU); rgD + killed spores; rgD + live spores + alum (2.0 mg); rgD + killed spores + alum; rgD + alum_, and rgD + PBS. Mice from rgD + live spores group showed an increase in rgD IgG titers from the 21st day until the end of the experiment. The groups of live and killed spores, associated to alum, had similar levels of IgG titers with no significant difference between each other; however, by the 14th and 28th day until the end of the experiment, presented higher IgG titers in comparison to the rgD + alum group. Moreover, increased serum levels of IgG1, IgG2a, and IgG2b were detected in mice that received spores in the vaccine formulation. The spores associated with alum groups showed neutralizing BoHV-5 antibodies and high mRNA transcription of the cytokines IFN-γ (66-fold), IL-17 (14-fold), and IL-12 (2.8-fold). In conclusion, our data demonstrated that the B. toyonensis spores, live or killed, associated with alum increased the adjuvanticity for BoHV-5 rgD in mice, suggesting the use of B. toyonensis spores as a promising component for vaccine formulations.

Vaccination against cocaine using a modifiable dendrimer nanoparticle platform

Pharmacological therapies for the treatment of cocaine addiction have had disappointing efficacy, and the lack of recent developments in the clinical care of cocaine-addicted patients indicates a need for novel treatment strategies. Recent studies have shown that vaccination against cocaine to elicit production of antibodies that reduce concentrations of free drug in the blood is a promising method to protect against the effects of cocaine and reduce rates of relapse. However, the poorly immunogenic nature of cocaine remains a major hurdle to active immunization. Therefore, we hypothesized that strategies to increase targeted exposure of cocaine to the immune system may produce a more effective vaccine. To specifically direct an immune response against cocaine, in the present study we have conjugated a cocaine analog to a dendrimer-based nanoparticle carrier with MHC II-binding moieties that previously has been shown to activate antigen-presenting cells necessary for antibody production. This strategy produced a rapid, prolonged, and high affinity anti-cocaine antibody response without the need for an adjuvant. Surprisingly, additional evaluation using multiple adjuvant formulations in two strains of inbred mice found adjuvants were either functionally redundant or deleterious in the vaccination against cocaine using this platform. The use of conditioned place preference in rats after administration of this vaccine provided proof of concept for the ability of this vaccine to diminish cocaine reward. Together these data demonstrate the intrinsic efficacy of an immune-targeting dendrimer-based cocaine vaccine, with a vast potential for design of future vaccines against other poorly immunogenic antigens by substitution of the conjugated cargo.

Overcoming immune dysfunction in the elderly: trained immunity as a novel approach

People with advanced age have a higher susceptibility to infections and exhibit increased mortality and morbidity as the ability of the immune system to combat infections decreases with age. While innate immune cells display functional defects such as decreased phagocytosis, chemotaxis and cytokine production, adaptive immune cells exhibit reduced receptor diversity, defective antibody production and a sharp decline in naive cell populations. Successful responses to vaccination in the elderly are critical to prevent common infections such as influenza and pneumonia, but vaccine efficacy decreases in older individuals compared with young adults. Trained immunity is a newly emerging concept that showed that innate immune cells possess non-specific immunological memory established through epigenetic and metabolic reprogramming upon encountering certain pathogenic stimuli. Clinical studies suggest that trained immunity can be utilized to enhance immune responses against infections and improve the efficiency of vaccinations in adults; however, how trained immunity responses are shaped with advanced age is still an open question. In this review, we provide an overview of the age-related changes in the immune system with a focus on innate immunity, discuss current vaccination strategies for the elderly, present the concept of trained immunity and propose it as a novel approach to enhance responses against infections and vaccinations in the elderly population.

Aeromonas salmonicida infection kinetics and protective immune response to vaccination in sablefish (Anoplopoma fimbria)

Effective vaccine programs against Aeromonas salmonicida have been identified as a high priority area for the sablefish (Anoplopoma fimbria) aquaculture. In this study, we established an A. salmonicida infection model in sablefish to evaluate the efficacy of commercial vaccines and an autogenous vaccine preparation. Groups of 40 fish were intraperitoneally (ip) injected with different doses of A. salmonicida J410 isolated from infected sablefish to calculate the median lethal dose (LD₅₀). Samples of blood, head kidney, spleen, brain, and liver were also collected at different time points to determine the infection kinetics. The LD₅₀ was estimated as ~3 × 10⁵ CFU/dose. To evaluate the immune protection provided by an autogenous vaccine and two commercial vaccines in a common garden experimental design, 140 fish were PIT-tagged, vaccinated and distributed equally into 4 tanks (35 fish for each group, including a control group). Blood samples were taken every 2 weeks to evaluate IgM titers. At 10 weeks post-immunization, all groups were ip challenged with 100 times the calculated LD₅₀ for A. salmonicida J410. A. salmonicida was detected after 5 days post-infection (dpi) in all collected tissues. At 30 days post-challenge the relative percentage survival (RPS) with respect to the control group was calculated for each vaccine. The RPS for the bacterin mix was 65.22%, for Forte Micro 4® vaccine was 56.52% and for Alpha Ject Micro 4® was 30.43%, and these RPS values were reflected by A. salmonicida tissue colonization levels at 10 days post-challenge. Total IgM titers peaked at 6-8 weeks post-immunization, where the autogenous vaccine group showed the highest IgM titers and these values were consistent with the RPS data. Also, we determined that the A. salmonicida A-layer binds to immunoglobulins F(ab)' in a non-specific fashion, interfering with immune assays and potentially vaccine efficacy. Our results indicate that vaccine design influences sablefish immunity and provide a guide for future sablefish vaccine programs.

Lignin nanoparticles as a promising vaccine adjuvant and delivery system for ovalbumin

Vaccination is the most effective strategy of preventing and treating infectious diseases and the most significant issue in the development of potent vaccines is the sufficient immunogenicity and safety of vaccines. The main goal of the present study is to develop a potent and safe vaccine adjuvant that can also stabilize antigen formulations during preparation and storage. In this study, the model antigen ovalbumin (OVA) was encapsulated in polymeric nanoparticles based on lignin (OVA-LNPs). The nanoparticles had a particle size of 216 nm and a low polydispersity index. The nanoparticles were negatively charged (-26.7 mV) with high encapsulation efficiency 81.6% of OVA antigen. In vitro studies of the nanoparticles were tested against dendritic cells (DCs), specialized antigen-presenting cells (APCs). The results showed no cytotoxic effect from LNPs and a significantly higher percentage of dendritic cells have taken up the antigen when encapsulated inside LNPs in contrast to free OVA. The nanoparticle was administered intradermally to BALB/c mice and the resulting time-dependent systemic immune responses towards OVA were assessed by measuring the OVA-specific IgG titers using an enzyme-linked immunosorbent assay (ELISA). In vivo immunization with OVA-LNPs induced a stronger IgG antibody response than that induced by free OVA or alum adjuvanted OVA. Enhanced immunization by OVA-LNPs was attributed to the observed efficient uptake of the antigen by dendritic cells. These findings demonstrate that LNPs are promising to be used as vaccine adjuvant and delivery system for the induction of long-term immune responses.