Design of nanomaterial based systems for novel vaccine development

A novel strategy to elicit enduring anti-morphine immunity and relief from addiction by targeting Acr1 protein nano vaccine through TLR-2 to dendritic cells

Morphine addiction poses a significant challenge to global healthcare. Current opioid substitution therapies, such as buprenorphine, naloxone and methadone are effective but often lead to dependence. Thus, exploring alternative treatments for opioid addiction is crucial. We have developed a novel vaccine that presents morphine and Pam3Cys (a TLR-2 agonist) on the surface of Acr1 nanoparticles. This vaccine has self-adjuvant properties and targets TLR-2 receptors on antigen-presenting cells, particularly dendritic cells. Our vaccination strategy promotes the proliferation and differentiation of morphine-specific B-cells and Acr1-reactive CD4 T-cells. Additionally, the vaccine elicited the production of high-affinity anti-morphine antibodies, effectively eliminating morphine from the bloodstream and brain in mice. It also reduced the expression of addiction-associated μ-opioid receptor and dopamine genes. The significant increase in memory CD4 T-cells and B-cells indicates the vaccine's ability to induce long-lasting immunity against morphine. This vaccine holds promise as a prophylactic measure against morphine addiction.

Self-Assembling E2-Based Nanoparticles Improve Vaccine Thermostability and Protective Immunity against CSFV

Classical swine fever virus (CSFV) is a highly contagious pathogen causing significant economic losses in the swine industry. Conventional inactivated or attenuated live vaccines for classical swine fever (CSF) are effective but face biosafety concerns and cannot distinguish vaccinated animals from those infected with the field virus, complicating CSF eradication efforts. It is noteworthy that nanoparticle (NP)-based vaccines resemble natural viruses in size and antigen structure, and offer an alternative tool to circumvent these limitations. In this study, we developed an innovative vaccine delivery scaffold utilizing self-assembled mi3 NPs, which form stable structures carrying the CSFV E2 glycoprotein. The expressed yeast E2-fused protein (E2-mi3 NPs) exhibited robust thermostability (25 to 70 °C) and long-term storage stability at room temperature (25 °C). Interestingly, E2-mi3 NPs made with this technology elicited enhanced antigen uptake by RAW264.7 cells. In a rabbit model, the E2-mi3 NP vaccine against CSFV markedly increased CSFV-specific neutralizing antibody titers. Importantly, it conferred complete protection in rabbits challenged with the C-strain of CSFV. Furthermore, we also found that the E2-mi3 NP vaccines triggered stronger cellular (T-lymphocyte proliferation, CD8+ T-lymphocytes, IFN-γ, IL-2, and IL-12p70) and humoral (CSFV-specific neutralizing antibodies, CD4+ T-lymphocytes, and IL-4) immune responses in pigs than the E2 vaccines. To sum up, these structure-based, self-assembled mi3 NPs provide valuable insights for novel antiviral strategies against the constantly infectious agents.

Biochemical transformations of inorganic nanomedicines in buffers, cell cultures and organisms

The field of nanomedicine is rapidly evolving, with new materials and formulations being reported almost daily. In this respect, inorganic and inorganic-organic composite nanomaterials have gained significant attention. However, the use of new materials in clinical trials and their final approval as drugs has been hampered by several challenges, one of which is the complex and difficult to control nanomaterial chemistry that takes place within the body. Several reviews have summarized investigations on inorganic nanomaterial stability in model body fluids, cell cultures, and organisms, focusing on their degradation as well as the influence of corona formation. However, in addition to these aspects, various chemical reactions of nanomaterials, including phase transformation and/or the formation of new/secondary nanomaterials, have been reported. In this review, we discuss recent advances in our understanding of biochemical transformations of medically relevant inorganic (composite) nanomaterials in environments related to their applications. We provide a refined terminology for the primary reaction mechanisms involved to bridge the gaps between different disciplines involved in this research. Furthermore, we highlight suitable analytical techniques that can be harnessed to explore the described reactions. Finally, we highlight opportunities to utilize them for diagnostic and therapeutic purposes and discuss current challenges and research priorities.

The influence of component structural arrangement on peptide vaccine immunogenicity

Peptide-based subunit vaccines utilise minimal immunogenic components (i.e. peptides) to generate highly specific immune responses, without triggering adverse reactions. However, strong adjuvants and/or effective delivery systems must be incorporated into such vaccines, as peptide antigens cannot induce substantial immune responses on their own. Unfortunately, many adjuvants are too weak or too toxic to be used in combination with peptide antigens. These shortcomings have been addressed by the conjugation of peptide antigens with lipidic/ hydrophobic adjuvanting moieties. The conjugates have shown promising safety profiles and improved immunogenicity without the help of traditional adjuvants and have been efficient in inducing desired immune responses following various routes of administration, including subcutaneous, oral and intranasal. However, not only conjugation per se, but also component arrangement influences vaccine efficacy. This review highlights the importance of influence of the vaccine chemical structure modification on the immune responses generated. It discusses a variety of factors that affect the immunogenicity of peptide conjugates, including: i) self-adjuvanting moiety length and number; ii) the orientation of epitopes and self-adjuvanting moieties in the conjugate; iii) the presence of spacers between conjugated components; iv) multiepitopic arrangement; and v) the effect of chirality on vaccine efficacy.

How to evaluate the potential toxicity of therapeutic carbon nanomaterials? A comprehensive study of carbonized nanogels with multiple animal toxicity test models

Carbon-based nanomaterials have great potential in medical applications, especially in the treatment of infectious diseases and even tumors. However, to safely execute the application of carbon nanomaterials in human treatments, conducting safety assessments and establishing suitable evaluation criteria are necessary. In this study, lysine-carbonized nanogels (Lys-CNGs) that display antibacterial and antiviral abilities were employed in a comprehensive evaluation of their toxicity profiles through assessments in different animal models and growth stages. It was observed that zebrafish at the embryo and eleutheroembryo stages experienced significant toxic effects at a concentration of 15-fold the recommended dosage (0.5 ppm), whereas adult zebrafish following long-term consumption of fodder containing Lys-CNGs presented no adverse effects. Further microbiota analysis indicated that Lys-CNGs did not cause significant changes in the composition of the intestinal bacteria. In contrast, in the toxicity assessments with mammalian animal models, the Lys-CNGs showed no adverse effects, such as weight loss, dermal irritation, and skin sensitization responses in rabbits and guinea pigs, even at a high dose of 2000 mg/kg body weight. Our study revealed that Lys-CNGs have different toxic effects on different growth stages of zebrafish. Researchers in this field should carefully consider the implications of these toxicity profiles during the development of therapeutic carbon-based nanomaterials and for comparison of studies.

Self-Assembly of Flagellin into Immunostimulatory Ring-like Nanostructures as an Antigen Delivery System

Proteinaceous nanoparticles represent attractive antigen carriers for vaccination as their size and repetitive antigen displays that mimic most viral particles enable efficient immune processing. However, these nanocarriers are often unable to stimulate efficiently the innate immune system, requiring coadministration with adjuvants to promote long-lasting protective immunity. The protein flagellin, which constitutes the primary constituent of the bacterial flagellum, has been widely evaluated as an antigen carrier due to its intrinsic adjuvant properties involving activation of the innate immune receptor Toll-like receptor 5 (TLR5). Although flagellin is known for its ability to self-assemble into micron-scale length nanotubes, few studies have evaluated the potential usage of flagellin-based nanostructures as immunostimulatory antigen carriers. In this study, we reported for the first time a strategy to guide the self-assembly of a flagellin protein from Bacillus subtilis, Hag, into lower aspect ratio nanoparticles by hindering non-covalent interactions responsible for its elongation into nanotubes. We observed that addition of an antigenic sequence derived from the influenza A virus (3M2e) at the C-terminus of this flagellin, as opposed to positioning the epitope into mid-sequence, precluded filament elongation and resulted in low aspect ratio ring-like nanostructures upon salting-out-induced self-assembly. These nanostructures displayed the antigen at their surface and shared morphological and structural characteristics with flagellin nanotubes, with a diameter of approximately 12 nm, and an α-helix-rich secondary structure. Flagellin ring-like nanostructures were efficiently internalized by antigen-presenting cells, and avidly activated the TLR5 in vitro as well as the innate and adaptive immune responses. Intranasal immunization of mice with these nanostructures resulted in the potentiation of the antigen-specific antibody response and protection against a lethal infection with the influenza A virus, illustrating the potential of these intrinsically immunostimulatory nanostructures as antigen carriers.

Nanocarriers-Assisted Needle-Free Vaccine Delivery Through Oral and Intranasal Transmucosal Routes: A Novel Therapeutic Conduit

Drug delivery using oral route is the most popular, convenient, safest and least expensive approach. It includes oral transmucosal delivery of bioactive compounds as the mucosal cavity offers an intriguing approach for systemic drug distribution. Owing to the dense vascular architecture and high blood flow, oral mucosal layers are easily permeable and can be an ideal site for drug administration. Recently, the transmucosal route is being investigated for other therapeutic candidates such as vaccines for their efficient delivery. Vaccines have the potential to trigger immune reactions and can act as both prophylactic and therapeutic conduit to a variety of diseases. Administration of vaccines using transmucosal route offers multiple advantages, the most important one being the needle-free (non-invasive) delivery. Development of needle-free devices are the most recent and pioneering breakthrough in the delivery of drugs and vaccines, enabling patients to avoid needles, reducing anxiety, pain and fear as well as improving compliance. Oral, nasal and aerosol vaccination is a novel immunization approach that utilizes a nanocarrier to administer the vaccine. Nanocarriers improve the bioavailability and serve as adjuvants to elicit a stronger immune response, resulting in increased effectiveness of vaccination. Drugs and vaccines with lower penetration abilities can also be delivered transmucosally while maintaining their biological function. The development of micro/nanocarriers for transmucosal delivery of macromolecules, vaccines and other substances is currently drawing much attention and a number of studies were performed recently. This comprehensive review is aimed to summarize the most recent investigations on needle-free and non-invasive approaches for the delivery of vaccines using oral transmucosal route, their strengths and associated challenges. The oral transmucosal vaccine delivery by nanocarriers is the most upcoming advancement in efficient vaccine delivery and this review would help further research and trials in this field.

Applications of nanoengineered therapeutics and vaccines: special emphasis on COVID-19

Nanomedicine provides innovative strategies that had significantly improved drug and gene delivery and allowed control over the engineering of therapeutics, diagnostics, vaccines, and other medical devices, for a diversity of medical applications. This review focuses on the current attempts to develop potent nanoengineered vaccines and therapeutics against coronaviruses, and the recent fabrication strategies and design principles to control acute infections from the escalating SARS-CoV-2 pandemic. Nanomedical approaches provide versatile platforms that can be utilized to enhance the overall potency, safety, and stability of vaccines, thus augmenting the desired immune response. Their modulable conformational features of size, shape, surface charge, antigen display, and composition allow for precise tuning and optimization of the nanoconstructs for the management of a variety of diseases and pathological conditions. The ability to control the release of their encapsulated cargoes and the possibility of surface decoration with various moieties support the construction of multifunctional nanomaterials that ultimately boost and prolong the immune response elicited and/or therapeutic effects, selectively at the diseased tissues and target sites.

How can we develop an effective subunit vaccine to achieve successful malaria eradication?

Malaria, a mosquito-borne infection, is the most widespread parasitic disease. Despite numerous efforts to eradicate malaria, this disease is still a health concern worldwide. Owing to insecticide-resistant vectors and drug-resistant parasites, available controlling measures are insufficient to achieve a malaria-free world. Thus, there is an urgent need for new intervention tools such as efficient malaria vaccines. Subunit vaccines are the most promising malaria vaccines under development. However, one of the major drawbacks of subunit vaccines is the lack of efficient and durable immune responses including antigen-specific antibody, CD4⁺, and CD8⁺ T-cell responses, long-lived plasma cells, memory cells, and functional antibodies for parasite neutralization or inhibition of parasite invasion. These types of responses could be induced by whole organism vaccines, but eliciting these responses with subunit vaccines has been proven to be more challenging. Consequently, subunit vaccines require several policies to overcome these challenges. In this review, we address common approaches that can improve the efficacy of subunit vaccines against malaria.

Self-Assembling Nanovaccine Enhances Protective Efficacy Against CSFV in Pigs

Classical swine fever virus (CSFV) is a highly contagious pathogen, which pose continuous threat to the swine industry. Though most attenuated vaccines are effective, they fail to serologically distinguish between infected and vaccinated animals, hindering CSFV eradication. Beneficially, nanoparticles (NPs)-based vaccines resemble natural viruses in size and antigen structure, and offer an alternative tool to circumvent these limitations. Using self-assembling NPs as multimerization platforms provides a safe and immunogenic tool against infectious diseases. This study presented a novel strategy to display CSFV E2 glycoprotein on the surface of genetically engineered self-assembling NPs. Eukaryotic E2-fused protein (SP-E2-mi3) could self-assemble into uniform NPs as indicated in transmission electron microscope (TEM) and dynamic light scattering (DLS). SP-E2-mi3 NPs showed high stability at room temperature. This NP-based immunization resulted in enhanced antigen uptake and up-regulated production of immunostimulatory cytokines in antigen presenting cells (APCs). Moreover, the protective efficacy of SP-E2-mi3 NPs was evaluated in pigs. SP-E2-mi3 NPs significantly improved both humoral and cellular immunity, especially as indicated by the elevated CSFV-specific IFN-γ cellular immunity and >10-fold neutralizing antibodies as compared to monomeric E2. These observations were consistent to in vivo protection against CSFV lethal virus challenge in prime-boost immunization schedule. Further results revealed single dose of 10 μg of SP-E2-mi3 NPs provided considerable clinical protection against lethal virus challenge. In conclusion, these findings demonstrated that this NP-based technology has potential to enhance the potency of subunit vaccine, paving ways for nanovaccine development.

Biomaterials and nanomaterials for sustained release vaccine delivery

Vaccines are considered one of the most significant medical advancements in human history, as they have prevented hundreds of millions of deaths since their discovery; however, modern travel permits disease spread at unprecedented rates, and vaccine shortcomings like thermal sensitivity and required booster shots have been made evident by the COVID-19 pandemic. Approaches to overcoming these issues appear promising via the integration of vaccine technology with biomaterials, which offer sustained-release properties and preserve proteins, prevent conformational changes, and enable storage at room temperature. Sustained release and thermal stabilization of therapeutic biomacromolecules is an emerging area that integrates material science, chemistry, immunology, nanotechnology, and pathology to investigate different biocompatible materials. Biomaterials, including natural sugar polymers, synthetic polyesters produced from biologically derived monomers, hydrogel blends, protein-polymer blends, and metal-organic frameworks, have emerged as early players in the field. This overview will focus on significant advances of sustained release biomaterial in the context of vaccines against infectious disease and the progress made towards thermally stable "single-shot" formulations. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease.

Influenza vaccines: Past, present, and future

Globally, infection by seasonal influenza viruses causes 3-5 million cases of severe illness and 290,000-650,000 respiratory deaths each year. Various influenza vaccines, including inactivated split- and subunit-type, recombinant and live attenuated vaccines, have been developed since the 1930s when it was discovered that influenza viruses could be cultivated in embryonated eggs. However, the protection rate offered by these vaccines is rather low, especially in very young children and the elderly. In this review, we describe the history of influenza vaccine development, the immune responses induced by the vaccines and the adjuvants applied. Further, we suggest future directions for improving the effectiveness of influenza vaccines in all age groups. This includes the development of an influenza vaccine that induces a balanced T helper cell type 1 and type 2 immune responses based on the understanding of the immune system, and the development of a broad-spectrum influenza vaccine that can increase effectiveness despite antigen shifts and drifts, which are characteristics of the influenza virus. A brighter future can be envisaged if the development of an adjuvant that is safe and effective is realized.

The Brief Analysis of Peptide-combined Nanoparticle: Nanomedicine's Unique Value

Therapeutic peptides (TPs) are biological macromolecules which can act as neurotransmitters, hormones, ion channel ligands and growth factors. Undoubtedly, TPs are crucial in modern medicine. But low bio-stability and some special adverse reactions reduce their places to the application. With the development of nanotechnology, nanoparticles (NPs) in pharmaceutical science gained much attention. They can encapsulate the TPs into their membrane or shell. Therefore, they can protect the TPs against degradation and then increase the bioavailability, which was thought to be the biggest advantage of them. Additionally, targeting was also studied to improve the effect of TPs. However, there were some drawbacks of nano TPs like low loading efficiency and difficulty to manufacture. Nowadays, lots of studies focused on improving effect of TPs by preparing nanoparticles. In this review, we presented a brief analysis of peptide-combined nanoparticles. Their advantages and disadvantages were listed in terms of mechanism. And several examples of applications were summarized.

Role of membrane-embedded drug efflux ABC transporters in the cancer chemotherapy

One of the major problems being faced by researchers and clinicians in leukemic treatment is the development of multidrug resistance (MDR) which restrict the action of several tyrosine kinase inhibitors (TKIs). MDR is a major obstacle to the success of cancer chemotherapy. The mechanism of MDR involves active drug efflux transport of ABC superfamily of proteins such as Pglycoprotein (P-gp/ABCB1), multidrug resistance-associated protein 2 (MRP2/ABCC2), and breast cancer resistance protein (BCRP/ABCG2) that weaken the effectiveness of chemotherapeutics and negative impact on the future of anticancer therapy. In this review, the authors aim to provide an overview of various multidrug resistance (MDR) mechanisms observed in cancer cells as well as the various strategies developed to overcome these MDR. Extensive studies have been carried out since last several years to enhance the efficacy of chemotherapy by defeating these MDR mechanisms with the use of novel anticancer drugs that could escape from the efflux reaction, MDR modulators or chemosensitizers, multifunctional nanotechnology, and RNA interference (RNAi) therapy.

Gold nanoparticles for preparation of antibodies and vaccines against infectious diseases

INTRODUCTION

Vaccination remains very effective in stimulating protective immune responses against infections. An important task in antibody and vaccine preparation is to choose an optimal carrier that will ensure a high immune response. Particularly promising in this regard are nanoscale particle carriers. An antigen that is adsorbed or encapsulated by nanoparticles can be used as an adjuvant to optimize the immune response during vaccination. a very popular antigen carrier used for immunization and vaccination is gold nanoparticles, with are being used to make new vaccines against viral, bacterial, and parasitic infections.

AREAS COVERED

This review summarizes what is currently known about the use of gold nanoparticles as an antigen carrier and adjuvant to prepare antibodies in vivo and design vaccines against viral, bacterial, and parasitic infections. The basic principles, recent advances, and current problems in the use of gold nanoparticles are discussed.

EXPERT OPINION

Gold nanoparticles can be used as adjuvants to increase the effectiveness of vaccines by stimulating antigen-presenting cells and ensuring controlled antigen release. Studying the characteristics of the immune response obtained from the use of gold nanoparticles as a carrier and an adjuvant will permit the particles' potential for vaccine design to be increased.

Local mucosal immunization of self-assembled nanofibers elicits robust antitumor effects in an orthotopic model of mouse genital tumors

Human papillomavirus (HPV) is the identified causative agent of cervical cancer. Current therapeutic HPV vaccine candidates lack significant clinical efficacy, which can be attributed to insufficient activation of effector cells, lack of effective modification of the immunosuppressive tumor microenvironment, and the limitations of applied tumor models for preclinical vaccine evaluation. Here, a mouse model of orthotopic genital tumors was used to assess the effect of self-assembled nanofibers on eliciting a robust antitumor response via local mucosal immunization. A candidate vaccine was obtained by fusing HPV16 E7_44-62 to the self-assembling peptide Q11, which was assembled into nanofibers in a salt solution. Mice bearing an established genital TC-1 tumor were immunized with nanofibers through the intravaginal, intranasal, or subcutaneous route. Mucosal vaccination, especially via the intravaginal route, was more effective for suppressing tumor growth than subcutaneous immunization. The potential underlying mechanisms include promoting the systemic generation and tumor accumulation of antigen-specific cytotoxic T lymphocytes expressing high levels of interferon (IFN)-γ or granzyme-B, and reducing the tumor infiltration of immunosuppressive regulatory T cells and myeloid-derived suppressor cells. The levels of IFN-γ, the chemokines CXCL9 and CXCL10, and CXCR3⁺CD8⁺ T cells were significantly increased in tumor tissues, which may account for the improved recruitment of effector T cells into the tumor. Local mucosal immunization of nanofibers via the intravaginal route represents a new and promising vaccination strategy for the treatment of genital tumor lesions such as cervical cancer.

Biomimic strategies for modulating the interaction between particle adjuvants and antigen-presenting cells

The design strategies of particle adjuvants by mimicking natural pathogens to strengthen their interaction with antigen-presenting cells.

Ferritin nanocage-based antigen delivery nanoplatforms: epitope engineering for peptide vaccine design

Biomedical applications and nanotechnological advances, including constrained synthesis, multimodal imaging, drug delivery, and bioassay, have strongly benefited from employing ferritin nanocages due to their remarkable properties of easy engineering, great biocompatible features, large capacity and so on. In this study, ferritin nanocages were used to display epitopes (model antigens derived from Enterovirus 71 (EV71) with different length) on C- and N-terminals and the loop zone to search for the optimal position for the fusion of the epitopes to the vaccine platform. The longest epitope displayed on the N-terminal and loop zone as well as the second longest peptide displayed on the loop zone of ferritin resulted in 100% passive protection of newborn BALB/c mice from the lethal EV71. This suggests that peptides fused onto the loop zone of ferritin could induce strong immune response. Our results increase the versatility of the vaccine platform and provide more options for the production of stable constructs, suggesting the potential future clinical applicability of ferritin-based antigen delivery nanoplatforms.

Artificially designed hepatitis B virus core particles composed of multiple epitopes of type A and O foot-and-mouth disease virus as a bivalent vaccine candidate

Recently, many countries, including China, have experienced a series of type A and O foot-and-mouth disease virus (FMDV) epidemics, causing serious economic losses. Although concerns about the safety of inactivated FMD vaccines have been raised, the development of a safe and effective subunit vaccine is necessary. We constructed two chimeric virus-like particles (VLPs; rHBc/AO and rHBc/AOT VLPs) displaying tandem repeats of B cell epitopes (VP1 residue 134-161 and 200-213) derived from type A and O FMDV and one T cell epitope (3 A residue 21-35) using the truncated hepatitis B virus core (HBc) carrier. Our results indicate that the chimeric HBc can self-assemble into VLPs with these FMDV epitopes displayed on the surface. Immunization with the chimeric VLPs induced specific IgG and neutralization antibodies against type A and O FMDV in mice. Compared with the commercial type A/O FMDV bivalent inactivated vaccine, rHBc/AO and rHBc/AOT VLPs significantly stimulated the production of Th1 type cytokines (IFN-γ and IL-2), whereas Th2 cytokine production (IL-4 and IL-10) was decreased. Compared with rHBc/AO, rHBc/AOT induced increased Th2 cytokine and specific IgG production. These results demonstrate that the VLPs constructed in the current study induced both humoral and cellular immune responses and may represent potential bivalent VLP vaccines targeting both FMDV type A and O strains.

Nucleic acids presenting polymer nanomaterials as vaccine adjuvants

Most vaccines developed today include only the antigens that best stimulate the immune system rather than the entire virus or microbe, which makes vaccine production and use safer and easier, though they lack potency to induce acceptable immunity and long-term protection. The incorporation of additional immune stimulating components, named adjuvants, is required to generate a strong protective immune response. Nucleic acids (DNA and RNA) and their synthetic analogs are promising candidates as vaccine adjuvants activating Toll-like receptors (TLRs). Additionally, in the last few years several nanocarriers have emerged as platforms for targeted co-delivery of antigens and adjuvants. In this review, we focus on the recent developments in polymer nanomaterials presenting nucleic acids as vaccine adjuvants. We aim to compare the effectiveness of the various classes of polymers in immune modulating materials (nanoparticles, dendrimers, single-chain particles, nanogels, polymersomes and DNA-based architectures). In particular, we address the critical role of parameters such as size, shape, complexation and release of TLR ligands, cellular uptake, stability, toxicity and potential importance of spatial control in ligand presentation.

Bacteriophage T4 nanoparticles for vaccine delivery against infectious diseases

Subunit vaccines containing one or more target antigens from pathogenic organisms represent safer alternatives to whole pathogen vaccines. However, the antigens by themselves are not sufficiently immunogenic and require additives known as adjuvants to enhance immunogenicity and protective efficacy. Assembly of the antigens into virus-like nanoparticles (VLPs) is a better approach as it allows presentation of the epitopes in a more native context. The repetitive, symmetrical, and high density display of antigens on the VLPs mimic pathogen-associated molecular patterns seen on bacteria and viruses. The antigens, thus, might be better presented to stimulate host's innate as well as adaptive immune systems thereby eliciting both humoral and cellular immune responses. Bacteriophages such as phage T4 provide excellent platforms to generate the nanoparticle vaccines. The T4 capsid containing two non-essential outer proteins Soc and Hoc allow high density array of antigen epitopes in the form of peptides, domains, full-length proteins, or even multi-subunit complexes. Co-delivery of DNAs, targeting molecules, and/or molecular adjuvants provides additional advantages. Recent studies demonstrate that the phage T4 VLPs are highly immunogenic, do not need an adjuvant, and provide complete protection against bacterial and viral pathogens. Thus, phage T4 could potentially be developed as a "universal" VLP platform to design future multivalent vaccines against complex and emerging pathogens.

Application of built-in adjuvants for epitope-based vaccines

Several studies have shown that epitope vaccines exhibit substantial advantages over conventional vaccines. However, epitope vaccines are associated with limited immunity, which can be overcome by conjugating antigenic epitopes with built-in adjuvants (e.g., some carrier proteins or new biomaterials) with special properties, including immunologic specificity, good biosecurity and biocompatibility, and the ability to vastly improve the immune response of epitope vaccines. When designing epitope vaccines, the following types of built-in adjuvants are typically considered: (1) pattern recognition receptor ligands (i.e., toll-like receptors); (2) virus-like particle carrier platforms; (3) bacterial toxin proteins; and (4) novel potential delivery systems (e.g., self-assembled peptide nanoparticles, lipid core peptides, and polymeric or inorganic nanoparticles). This review primarily discusses the current and prospective applications of these built-in adjuvants (i.e., biological carriers) to provide some references for the future design of epitope-based vaccines.

Nano-multilamellar lipid vesicles (NMVs) enhance protective antibody responses against Shiga toxin (Stx2a) produced by enterohemorrhagic Escherichia coli strains (EHEC)

Microlipid vesicles (MLV) have a broad spectrum of applications for the delivery of molecules, ranging from chemical compounds to proteins, in both in vitro and in vivo conditions. In the present study, we developed a new set of nanosize multilayer lipid vesicles (NMVs) containing a unique combination of lipids. The NMVs enable the adsorption of histidine-tagged proteins at the vesicle surface and were demonstrated to be suitable for the in vivo delivery of antigens. The NMVs contained a combination of neutral (DOPC) and anionic (DPPG) lipids in the inner membrane and an external layer composed of DOPC, cholesterol, and a nickel-containing lipid (DGS-NTA [Ni]). NMVs combined with a recombinant form of the B subunit of the Shiga toxin (rStx2B) produced by certain enterohemorragic Escherichia coli (EHEC) strains enhanced the immunogenicity of the antigen after parenteral administration to mice. Mice immunized with rStx2B-loaded NMVs elicited serum antibodies capable of neutralizing the toxic activities of the native toxin; this result was demonstrated both in vitro and in vivo. Taken together, these results demonstrated that the proposed NMVs represent an alternative for the delivery of antigens, including recombinant proteins, generated in different expression systems.

Nanoformulations: A Valuable Tool in the Therapy of Viral Diseases Attacking Humans and Animals

Various viruses can be considered as one of the most frequent causes of human diseases, from mild illnesses to really serious sicknesses that end fatally. Numerous viruses are also pathogenic to animals and plants, and many of them, mutating, become pathogenic also to humans. Several cases of affecting humans by originally animal viruses have been confirmed. Viral infections cause significant morbidity and mortality in humans, the increase of which is caused by general immunosuppression of the world population, changes in climate, and overall globalization. In spite of the fact that the pharmaceutical industry pays great attention to human viral infections, many of clinically used antivirals demonstrate also increased toxicity against human cells, limited bioavailability, and thus, not entirely suitable therapeutic profile. In addition, due to resistance, a combination of antivirals is needed for life-threatening infections. Thus, the development of new antiviral agents is of great importance for the control of virus spread. On the other hand, the discovery and development of structurally new antivirals represent risks. Therefore, another strategy is being developed, namely the reformulation of existing antivirals into nanoformulations and investigation of various metal and metalloid nanoparticles with respect to their diagnostic, prophylactic, and therapeutic antiviral applications. This chapter is focused on nanoscale materials/formulations with the potential to be used for the treatment or inhibition of the spread of viral diseases caused by human immunodeficiency virus, influenza A viruses (subtypes H3N2 and H1N1), avian influenza and swine influenza viruses, respiratory syncytial virus, herpes simplex virus, hepatitis B and C viruses, Ebola and Marburg viruses, Newcastle disease virus, dengue and Zika viruses, and pseudorabies virus. Effective antiviral long-lasting and target-selective nanoformulations developed for oral, intravenous, intramuscular, intranasal, intrarectal, intravaginal, and intradermal applications are discussed. Benefits of nanoparticle-based vaccination formulations with the potential to secure cross protection against divergent viruses are outlined as well.

Targeting strategies of liposomal subunit vaccine delivery systems to improve vaccine efficacy

Liposomes are versatile delivery systems and immunological adjuvants that not only can load various antigens, such as proteins, peptides, nucleic acids and carbohydrates, but also can combine them with immunostimulators. Liposomes have great potential in the development of new types of vaccines, and much effort has been devoted to enhancing vaccine efficacy in recent years. Different types of immune cells such as macrophages and dendritic cells play an important role in the immune response and in preventing or treating cancer, allergy or many other infectious diseases. Targeting liposome-based delivery systems to certain immune cells and organs is one of the most effective measures in such treatments. Extensive research has shown that liposomes combined with immunostimulators or modified with pattern recognition receptor ligands can target various immune cells and the lymphatic system, thus not only inducing and promoting the desired immune response but also decreasing adverse effects throughout the body and avoiding targeting irrelevant cell types or tissues. Therefore, in this review, we outline some targeting strategies that can be adopted in the design of liposomal vaccines to improve vaccine efficacy, and we summarise the related liposome-based vaccine applications in several diseases. These applications have great potential to treat or prevent some infectious and intractable diseases.

Aluminum (oxy) Hydroxide Nanorods Activate an Early Immune Response in Pseudomonas aeruginosa Vaccine

Bacterial vaccines have been widely used to prevent infectious diseases, especially in veterinary medicine. Although there are many reports on bacterin adjuvants, only a few contain innovations in bacterin adjuvants. Taking this into consideration, in this study we designed and synthesized a new aluminum (oxy) hydroxide (AlOOH) nanorod (Al-NR) with a diameter of 200 ± 80 nm and a length of 1.1 ± 0.6 μm. Using whole- Pseudomonas aeruginosa PAO1 as antigens, we showed that the bacterial antigens of P. aeruginosa PAO1 adsorbed on the Al-NRs induced a quick and stronger antigen-specific antibody response than those of the other control groups, especially in the early stage of immunization. Furthermore, the level of antigen-specific IgG was approximately 4-fold higher than that of the no adjuvant group and 2.5-fold higher than those of other adjuvant groups in the first week after the initial immunization. The potent adjuvant activity of the Al-NRs was attributed to the rapid presentation of antigen adsorbed on them by APCs. Additionally, Al-NRs induced a milder local inflammation than the other adjuvants. In short, we confirmed that Al-NRs, enhancing both humoral and cellular immune responses, are a potentially promising vaccine adjuvant delivery system for inhibiting the whole- Pseudomonas aeruginosa infection.

Revival of a potent therapeutic maytansinoid agent using a strategy that combines covalent drug conjugation with sequential nanoparticle assembly

Maytansine and its related analogues are a class of highly potent anti-proliferation agents that have failed to be exploited as clinical drugs for human therapy due to unacceptable systemic toxicity. Here, we delineate a novel strategy that combines rational drug conjugation with subsequent nanoparticle assembly to systemically deliver this highly potent and toxic drug. To demonstrate this concept, we covalently coupled the thiolated maytansine derivative, the DM1 agent, to amphiphilic block co-polymers, polyethylene glycol (PEG)-block-polylactide (PLA), in varying molecular weights to generate two prodrug constructs (i.e., PEG_2K-PLA_2K-DM1 and PEG_2K-PLA_4K-DM1) via the maleimide-thiol reaction. The resulting two constructs are amenable to self-assembly in aqueous solutions and are systemically injectable for preclinical studies. In vivo evaluations indicate that PEG-PLA-DM1 conjugate-assembled nanoparticles (NPs) display substantially reduced drug toxicity compared to the free drug forms and NPs that physically encapsulate DM1. Furthermore, following systemic administration, these nanodrugs produced superior therapeutic efficacy over free DM1 in a colon tumor xenograft-bearing mouse model. Therefore, this study provides evidence that the conjugation of toxic drugs to assembling copolymers enables the alleviation of cancer drug toxicity and effective delivery of anticancer drugs. Thus, this DM1-formulated platform represents a new generation of nanotherapeutics that are available for further clinical evaluation.

Self-assembly of peptide amphiphiles for drug delivery: the role of peptide primary and secondary structures

Peptide amphiphiles (PAs), functionalized with alkyl chains, are capable of self-assembling into various nanostructures. Recently, PAs have been considered as ideal drug carriers due to their good biocompatibility, specific biological functions, and hypotoxicity to normal cells and tissues. Meanwhile, the nanocarriers formed by PAs are able to achieve controlled drug release and enhanced cell uptake in response to the stimulus of the physiological environment or specific biological factors in the location of the lesion. However, the underlying detailed drug delivery mechanism, especially from the aspect of primary and secondary structures of PAs, has not been systematically summarized or discussed. Focusing on the relationship between the primary and secondary structures of PAs and stimuli-responsive drug delivery applications, this review highlights the recent advances, challenges, and opportunities of PA-based functional drug nanocarriers, and their potential pharmaceutical applications are discussed.

Reduction-Responsive Codelivery System Based on a Metal-Organic Framework for Eliciting Potent Cellular Immune Response

Utilizing nanoparticles to deliver subunit vaccines can be viewed as a promising strategy for enhancing the immune response, especially with regard to cellular immunity to fight against infectious viruses and malignant cancer. Nevertheless, its applications are still far from practicality because of some limitations such as high cost, non-biocompatibility, non-biodegradability, and the inefficient stimulation of cytotoxic T lymphocyte (CTL) response. In this study, we use metal-organic framework (MOF) MIL-101-Fe-NH₂ nanoparticles as carriers to fabricate an innovative reduction-responsive antigen delivery system for cotransporting the antigen model ovalbumin (OVA) and an immune adjuvant, unmethylated cytosine-phosphate-guanine (CpG) oligonucleotide. In vitro cellular tests show that the MOF nanoparticles can not only greatly improve the uptake of OVA by the antigen-presenting cells but also smartly deliver both OVA and CpG into the same cell. By feat of the reductively controllable release of OVA and the promoting function of CpG, the delivery system can elicit strong cellular immunity and CTL response in mice. Moreover, the increased frequencies of effector memory T cells inspired by the delivery system indicate that it can induce a potent immune memory response. These results demonstrate that MOF nanoparticles are excellent vehicles for codelivering antigen and immune adjuvant and may find wider applications in biomedical fields.

Preparation of Modified Konjac Glucomannan Nanoparticles and their Application as Vaccine Adjuvants to Promote Ovalbumin-Induced Immune Response in Mice

PURPOSE

Herein, we reported a facile strategy for synthesis of two types of modified konjac glucomannan nanoparticles (NPs). The goal of this project was to explore the potential of the NPs as vaccine adjuvants.

METHODS

Firstly, anionic carboxymethylated konjac glucomannan (CKGM) and cationic quaternized konjac glucomannan (QKGM) were synthesized by chemical modification of konjac glucomannan (KGM). Subsequently, two types of NPs, CKGM/QKGM and sodium tripolyphosphate (TPP)/QKGM, were prepared through polyelectrolyte complex method and ionic cross-linking method, respectively. The thus-synthesized NPs were then loaded with ovalbumin (OVA) to further evaluate the effect of NPs on immune response in mice.

RESULTS

The encapsulation efficiency of OVA for CKGM/QKGM/OVA and TPP/QKGM/OVA NPs could be 49.2% and 67.7%, respectively, while the drug loading capacity could reach 10.9% and 60%. The NPs showed irregular spherical shape and exhibited good sustained-release properties. In vitro cytotoxicity assay revealed that both the blank and OVA-loaded NPs were not toxic to cells. The OVA-specific IgG, splenocytes proliferation and cytokine levels indicated that the OVA-induced humoral and cellular immune responses were up-regulated by OVA-loaded NPs. What's more, CKGM/QKGM/OVA NPs elicited both higher IL-2 and IFN-γ production, while TPP/QKGM/OVA NPs elicited both higher IL-4 and IL-10 production.

CONCLUSIONS

These results suggest that TPP/QKGM and CKGM/QKGM NPs are promising to be used as vaccine adjuvants. The TPP/QKGM/OVA NPs could induce stronger humoral immune response, while CKGM/QKGM/OVA NPs could enhance the cellular immune response more effectively.

Efficient Gene Delivery Mediated by a Helical Polypeptide: Controlling the Membrane Activity via Multivalency and Light-Assisted Photochemical Internalization (PCI)

The development of robust and nontoxic membrane-penetrating materials is highly demanded for nonviral gene delivery. Herein, a photosensitizer (PS)-embedded, star-shaped helical polypeptide was developed, which combines the advantages of multivalency-enhanced intracellular DNA uptake and light-strengthened endosomal escape to enable highly efficient gene delivery with low toxicity. 5,10,15,20-Tetrakis-(4-aminophenyl) porphyrin as a selected PS initiated ring-opening polymerization of N-carboxyanhydride and yielded a star-shaped helical polypeptide after side-chain functionalization with guanidine groups. The star polypeptide afforded a notably higher transfection efficiency and lower cytotoxicity than those of its linear analogue. Light irradiation caused almost complete (∼90%) endosomal release of the DNA cargo via the photochemical internalization (PCI) mechanism and further led to a 6-8-fold increment of the transfection efficiency in HeLa, B16F10, and RAW 264.7 cells, outperforming commercial reagent 25k PEI by up to 3 orders of magnitude. Because the PS and DNA cargoes were compartmentalized distantly in the core and polypeptide layers, respectively, the generated reactive oxygen species caused minimal damage to DNA molecules to preserve their transfection potency. Such multivalency- and PCI-potentiated gene delivery efficiency was also demonstrated in vivo in melanoma-bearing mice. This study thus provides a promising strategy to overcome the multiple membrane barriers against nonviral gene delivery.

Harnessing self-assembled peptide nanoparticles in epitope vaccine design

Vaccination has been one of the most successful breakthroughs in medical history. In recent years, epitope-based subunit vaccines have been introduced as a safer alternative to traditional vaccines. However, they suffer from limited immunogenicity. Nanotechnology has shown value in solving this issue. Different kinds of nanovaccines have been employed, among which virus-like nanoparticles (VLPs) and self-assembled peptide nanoparticles (SAPNs) seem very promising. Recently, SAPNs have attracted special interest due to their unique properties, including molecular specificity, biodegradability, and biocompatibility. They also resemble pathogens in terms of their size. Their multivalency allows an orderly repetitive display of antigens on their surface, which induces a stronger immune response than single immunogens. In vaccine design, SAPN self-adjuvanticity is regarded an outstanding advantage, since the use of toxic adjuvants is no longer required. SAPNs are usually composed of helical or β-sheet secondary structures and are tailored from natural peptides or de novo structures. Flexibility in subunit selection opens the door to a wide variety of molecules with different characteristics. SAPN engineering is an emerging area, and more novel structures are expected to be generated in the future, particularly with the rapid progress in related computational tools. The aim of this review is to provide a state-of-the-art overview of self-assembled peptide nanoparticles and their use in vaccine design in recent studies. Additionally, principles for their design and the application of computational approaches to vaccine design are summarized.

Chitosan nanoparticles based nanovaccines for cancer immunotherapy

Cancer immunotherapy based on tumor vaccine is very promising and intriguing for carcinoma treatment. Herein, antitumor nanovaccines consisting of self-assembled chitosan (CS) nanoparticles and two-component mucin1 (MUC1) glycopeptide antigens were reported. Two different kinds of polyanionic electrolyte [sodium tripolyphosphate (TPP) and γ-poly-L-glutamic acid (γ-PGA)] were combined with chitosan polymers to fabricate the diameter of nearly 400–500 nm CS nanoparticles by electrostatic interactions. The nanovaccines were constructed by physically mixing MUC1 glycopeptide antigens with CS nanoparticles, which reduced vaccine constructing complexity compared with traditional chemical total synthetic vaccines. Immunological studies revealed that the CS/γ-PGA nanoparticle could dramatically enhance the immunogenicity of peptide epitope and produce significantly high titers of IgG antibody which was even better than Freund’s adjuvant-containing vaccines.

Applications of Gold Nanoparticles in Nanomedicine: Recent Advances in Vaccines

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

Tailoring stimuli-responsive delivery system driven by metal-ligand coordination bonding

In this study, a novel coordination bonding system based on metal-tannic acid (TA) architecture on zein/carboxymethyl chitosan (CMCS) nanoparticles (NPs) was investigated for the pH-responsive drug delivery. CMCS has been reported to coat on zein NPs as delivery vehicles for drugs or nutrients in previous studies. The cleavage of either the "metal-TA" or "NH2-metal" coordination bonds resulted in significant release of guest molecules with high stimulus sensitivity, especially in mild acidic conditions. The prepared metal-TA-coated zein/CMCS NPs (zein/CMCS-TA/metal NPs) could maintain particle size in cell culture medium at 37°C, demonstrating good stability compared with zein/CMCS NPs. In vitro release behavior of doxorubicin hydrochloride (DOX)-loaded metal-TA film-coated zein/CMCS NPs (DOX-zein/CMCS-TA/metal NPs) showed fine pH responsiveness tailored by the ratio of zein to CMCS as well as the metal species and feeding concentrations. The blank zein/CMCS-TA/metal NPs (NPs-TA/metal) were of low cytotoxicity, while a high cytotoxic activity of DOX-zein/CMCS-TA/metal NPs (DOX-NPs-TA/metal) against HepG2 cells was demonstrated by in vitro cell assay. Confocal laser scanning microscopy (CLSM) and flow cytometry were combined to study the uptake efficiency of DOX-NPs or DOX-NPs-TA/metal. This system showed significant potential as a highly versatile and potent platform for drug delivery.

The Role of Eukaryotic and Prokaryotic ABC Transporter Family in Failure of Chemotherapy

Over the years chemotherapy failure has been a vital research topic as researchers have been striving to discover reasons behind it. The extensive studies carried out on chemotherapeutic agents confirm that resistance to chemotherapy is a major reason for treatment failure. “Resistance to chemotherapy,” however, is a comprehensive phrase that refers to a variety of different mechanisms in which ATP-binding cassette (ABC) mediated efflux dominates. The ABC is one of the largest gene superfamily of transporters among both eukaryotes and prokaryotes; it represents a variety of genes that code for proteins, which perform countless functions, including drug efflux – a natural process that protects cells from foreign chemicals. Up to date, chemotherapy failure due to ABC drug efflux is an active research topic that continuously provides further evidence on multiple drug resistance (MDR), aiding scientists in tackling and overcoming this issue. This review focuses on drug resistance by ABC efflux transporters in human, viral, parasitic, fungal and bacterial cells and highlights the importance of the MDR permeability glycoprotein being the mutual ABC transporter among all studied organisms. Current developments and future directions to overcome this problem are also discussed.

Potential of RNAi applications to control viral diseases of farmed shrimp

Viral pathogens pose a primary threat to global shrimp aquaculture. Despite the urgent industry need for them, practical anti-viral control methods are unavailable due, in part, to lack of an adaptive immune response in crustaceans that renders conventional vaccination methods ineffective. One currently studied method of high interest for protecting shrimp against viral infection relies on the post-transcriptional gene silencing mechanism called RNA interference (RNAi) that is induced by gene-specific constructs of double stranded RNA (dsRNA). Although this approach was first described for successful protection of shrimp against white spot disease (WSD) by injecting dsRNA specific to genes of white spot syndrome virus (WSSV) into shrimp in the laboratory in 2005 no practical method for use of dsRNA in shrimp farms has been developed to date. The apparent bottleneck for farm-scale applications of RNAi-mediated viral control in shrimp aquaculture is the lack of simple and cost-effective delivery methods. This review summarizes recent studies on use and delivery of dsRNA to shrimp via injection and oral routes in hatcheries and on farms and it discusses the research directions that might lead to development of practical methods for applications with farmed shrimp. Oral delivery methods tested so far include use of dsRNA-expressing bacteria as a component of dry feed pellets or use of living brine shrimp (Artemia) pre-fed with dsRNA before they are fed to shrimp. Also tested have been dsRNA enclosed in nanocontainers including chitosan, liposomes and viral-like particles (VLP) before direct injection or use as components of feed pellets for hatchery or pond-reared shrimp.

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

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

Aluminum hydroxide nanoparticles show strong activity to stimulate Th-1 immune response against tuberculosis

Many materials such as aluminum hydroxide have been tried as adjuvants to compensate low inherent immunogenicity of subunit vaccines. The aim of this study was to evaluate the specific immune response following the administration of aluminum hydroxide nanoparticles with EsxV antigen. The physiochemical properties of the nanoparticle were characterized in vitro. After subcutaneous immunization, cytokine secretion patterns including IFN-gama,IL-4, and TGF-beta levels were measured by indirect enzyme linked immunosorbent assay (ELISA). Aluminum hydroxide-NPs were demonstrated excellent effects to raise of IFN-γ secretion in compare to EsxV alone. Administration of aluminum hydroxide nanoparticles stimulates strong cellular immune response and could be considered as appropriate adjuvant against TB infection.