Particulate delivery systems for vaccination against bioterrorism agents and emerging infectious pathogens

The immunostimulatory roles of gold nanoparticles in immunization and vaccination against Brucella abortus antigens

One effective antigen carrier proposed for use in immunization and vaccination is gold nanoparticles. Prior work has shown that gold nanoparticles themselves have adjuvant properties. Currently, gold nanoparticles are used to design new diagnostic tests and vaccines against viral, bacterial, and parasitic infections. We investigated the use of gold nanoparticles as immunomodulators in immunization and vaccination with an antigen isolated from Brucella abortus. Gold nanoparticles with a diameter of 15 nm were synthesized for immunization of animals and were then conjugated to the isolated antigen. The conjugates were used to immunize white BALB/c mice. As a result, high-titer (1:10240) antibodies were produced. The respiratory and proliferative activities of immune cells were increased, as were the serum interleukin concentrations. The minimum antigen amount detected with the produced antibodies was ∼ 0.5 pg. The mice immunized with gold nanoparticles complexed with the B. abortus antigen were more resistant to B. abortus strain 82 than were the mice immunized through other schemes. This fact indicates that animal immunization with this conjugate enhances the effectiveness of the immune response. The results of this study are expected to be used in further work to examine the protective effect of gold nanoparticles complexed with the B. abortus antigen on immunized animals and to develop test systems for diagnosing brucellosis in the laboratory and in the field.

Global Catastrophic Biological Risks in the Post-COVID-19 World: Time to Act Is Now

Global Catastrophic Biological Risks (GCBRs) refer to events with biological agents that can result in unprecedented or catastrophic disasters that are beyond the collective response-abilities of nation-states and the existing governance instruments of global governance and international affairs. This article offers a narrative review, with a view to new hypothesis development to rethink GCBRs after coronavirus disease 2019 (COVID-19) so as to better prepare for future pandemics and ecological crises, if not to completely prevent them. To determine GCBRs' spatiotemporal contexts, define causality, impacts, differentiate the risk and the event, would improve theorization of GCBRs compared to the impact-centric current definition. This could in turn lead to improvements in preparedness, response, allocation of resources, and possibly deterrence, while actively discouraging lack of due biosecurity diligence. Critical governance of GCBRs in ways that unpack the political power-related dimensions could be particularly valuable because the future global catastrophic events might be different in quality, scale, and actors. Theorization of GCBRs remains an important task going forward in the 21st century in ways that draw from experiences in the field, while integrating flexibility, versatility, and critically informed responses to GCBRs.

Human Anthrax: Update of the Diagnosis and Treatment

Anthrax is one of the most important zoonotic diseases which primarily infects herbivores and occasionally humans. The etiological agent is Bacillus anthracis which is a Gram-positive, aerobic, spore-forming, nonmotile, rod-shaped bacillus. The spores are resistant to environmental conditions and remain viable for a long time in contaminated soil, which is the main reservoir for wild and domestic mammals. Infections still occur in low-income countries where they cause suffering and economic hardship. Humans are infected by contact with ill or dead animals, contaminated animal products, directly exposed to the spores in the environment or spores released as a consequence of a bioterrorist event. Three classical clinical forms of the disease, cutaneous, gastrointestinal and inhalation, are seen, all of which can potentially lead to sepsis or meningitis. A new clinical form in drug users has been described recently and named “injectional anthrax” with high mortality (>33%). The symptoms of anthrax in the early stage mimics many diseases and as a consequence it is important to confirm the diagnosis using a bacterial culture or a molecular test. With regards to treatment, human isolates are generally susceptible to most antibiotics with penicillin G and amoxicillin as the first choice, and ciprofloxacin and doxycycline serving as alternatives. A combination of one or more antibiotics is suggested in systemic anthrax. Controlling anthrax in humans depends primarily on effective control of the disease in animals. Spore vaccines are used in veterinary service, and an acellular vaccine is available for humans but its use is limited.

Current status and development prospects of aquatic vaccines

Diseases are a significant impediment to aquaculture's sustainable and healthy growth. The aquaculture industry is suffering significant financial losses as a result of the worsening water quality and increasing frequency of aquatic disease outbreaks caused by the expansion of aquaculture. Drug control, immunoprophylaxis, ecologically integrated control, etc. are the principal control strategies for fish infections. For a long time, the prevention and control of aquatic diseases have mainly relied on the use of various antibiotics and chemical drugs. However, long-term use of chemical inputs not only increases pathogenic bacteria resistance but also damages the fish and aquaculture environments, resulting in drug residues in aquatic products, severely impeding the development of the aquaculture industry. The development and use of aquatic vaccines are the safest and most effective ways to prevent aquatic animal diseases and preserve the health and sustainability of aquaculture. To give references for the development and implementation of aquatic vaccines, this study reviews the development history, types, inoculation techniques, mechanisms of action, development prospects, and challenges encountered with aquatic vaccines.

Immunogenicity and Reactogenicity in Q Fever Vaccine Development

Coxiella burnetii is an obligate intracellular bacterium which, in humans, causes the disease Q fever. Although Q fever is most often a mild, self-limiting respiratory disease, it can cause a range of severe syndromes including hepatitis, myocarditis, spontaneous abortion, chronic valvular endocarditis, and Q fever fatigue syndrome. This agent is endemic worldwide, except for New Zealand and Antarctica, transmitted via aerosols, persists in the environment for long periods, and is maintained through persistent infections in domestic livestock. Because of this, elimination of this bacterium is extremely challenging and vaccination is considered the best strategy for prevention of infection in humans. Many vaccines against C. burnetii have been developed, however, only a formalin-inactivated, whole cell vaccine derived from virulent C. burnetii is currently licensed for use in humans. Unfortunately, widespread use of this whole cell vaccine is impaired due to the severity of reactogenic responses associated with it. This reactogenicity continues to be a major barrier to access to preventative vaccines against C. burnetii and the pathogenesis of this remains only partially understood. This review provides an overview of past and current research on C. burnetii vaccines, our knowledge of immunogenicity and reactogenicity in C. burnetii vaccines, and future strategies to improve the safety of vaccines against C. burnetii.

Recent Trends in Protective Textiles against Biological Threats: A Focus on Biological Warfare Agents

The rising threats to worldwide security (affecting the military, first responders, and civilians) urge us to develop efficient and versatile technological solutions to protect human beings. Soldiers, medical personnel, firefighters, and law enforcement officers should be adequately protected, so that their exposure to biological warfare agents (BWAs) is minimized, and infectious microorganisms cannot be spread so easily. Current bioprotective military garments include multilayered fabrics integrating activated carbon as a sorptive agent and a separate filtrating layer for passive protection. However, secondary contaminants emerge following their accumulation within the carbon filler. The clothing becomes too heavy and warm to wear, not breathable even, preventing the wearer from working for extended hours. Hence, a strong need exists to select and/or create selectively permeable layered fibrous structures with bioactive agents that offer an efficient filtering capability and biocidal skills, ensuring lightweightness, comfort, and multifunctionality. This review aims to showcase the main possibilities and trends of bioprotective textiles, focusing on metal-organic frameworks (MOFs), inorganic nanoparticles (e.g., ZnO-based), and organic players such as chitosan (CS)-based small-scale particles and plant-derived compounds as bioactive agents. The textile itself should be further evaluated as the foundation for the barrier effect and in terms of comfort. The outputs of a thorough, standardized characterization should dictate the best elements for each approach.

Efficacy and Immune Response Elicited by Gold Nanoparticle- Based Nanovaccines against Infectious Diseases

The use of nanoparticles for developing vaccines has become a routine process for researchers and pharmaceutical companies. Gold nanoparticles (GNPs) are chemical inert, have low toxicity, and are easy to modify and functionalize, making them an attractive choice for nanovaccine development. GNPs are modified for diagnostics and detection of many pathogens. The biocompatibility and biodistribution properties of GNPs render them ideal for use in clinical settings. They have excellent immune modulatory and adjuvant properties. They have been used as the antigen carrier for the delivery system to a targeted site. Tagging them with antibodies can direct the drug or antigen-carrying GNPs to specific tissues or cells. The physicochemical properties of the GNP, together with its dynamic immune response based on its size, shape, surface charge, and optical properties, make it a suitable candidate for vaccine development. The clear outcome of modulating dendritic cells, T and B lymphocytes, which trigger cytokine release in the host, indicates GNPs' efficiency in combating pathogens. The high titer of IgG and IgA antibody subtypes and their enhanced capacity to neutralize pathogens are reported in multiple studies on GNP-based vaccine development. The major focus of this review is to illustrate the role of GNPs in developing nanovaccines against multiple infectious agents, ranging from viruses to bacteria and parasites. Although the use of GNPs has its shortcomings and a low but detectable level of toxicity, their benefits warrant investing more thought and energy into the development of novel vaccine strategies.

Conjugation-Free Multilamellar Protein-Lipid Hybrid Vesicles for Multifaceted Immune Responses

Various lipid-based nanocarriers have been developed for the co-delivery of protein antigens with immunological adjuvants. However, their in vivo potency in vaccine delivery is limited by structural instability, which causes off-target delivery and low cross-presentation efficacies. Recent works employ covalent cross-linking to stabilize the lipid nanostructures, though the immunogenicity and side effects of chemically modified protein antigens and lipids can cause a long-lasting safety issue. Here robust "conjugation-free" multilamellar protein antigen-lipid hybrid nanovesicles (MPLVs) are introduced through the antigen-mediated self-assembly of unilamellar lipid vesicles for the co-delivery of protein antigens and immunologic adjuvants. The nanocarriers coated with monophosphoryl lipid A and hyaluronic acids elicit highly increase antigen-specific immune responses in vitro and in vivo. The MPLVs increase the generation of immunological surface markers and cytokines in mouse-derived bone-marrow dendritic cells compared to soluble antigens with adjuvants. Besides, the vaccination of mice with the MPLVs significantly increase the production of anti-antigen antibody and interferon-gamma via the activation of CD4⁺ and CD8⁺ T cells, respectively. These findings suggest that MPLVs can serve as a promising nanovaccine delivery platform for efficient antigen cross-presentation through the efficient co-delivery of protein antigens with adjuvants.

Novel approaches for vaccine development

Vaccines are critical tools for maintaining global health. Traditional vaccine technologies have been used across a wide range of bacterial and viral pathogens, yet there are a number of examples where they have not been successful, such as for persistent infections, rapidly evolving pathogens with high sequence variability, complex viral antigens, and emerging pathogens. Novel technologies such as nucleic acid and viral vector vaccines offer the potential to revolutionize vaccine development as they are well-suited to address existing technology limitations. In this review, we discuss the current state of RNA vaccines, recombinant adenovirus vector-based vaccines, and advances from biomaterials and engineering that address these important public health challenges.

Emerging skin-targeted drug delivery strategies to engineer immunity: A focus on infectious diseases

INTRODUCTION

Infectious pathogens are global disrupters. Progress in biomedical science and technology has expanded the public health arsenal against infectious diseases. Specifically, vaccination has reduced the burden of infectious pathogens. Engineering systemic immunity by harnessing the cutaneous immune network has been particularly attractive since the skin is an easily accessible immune-responsive organ. Recent advances in skin-targeted drug delivery strategies have enabled safe, patient-friendly, and controlled deployment of vaccines to cutaneous microenvironments for inducing long-lived pathogen-specific immunity to mitigate infectious diseases, including COVID-19.

AREAS COVERED

This review briefly discusses the basics of cutaneous immunomodulation and provides a concise overview of emerging skin-targeted drug delivery systems that enable safe, minimally invasive, and effective intracutaneous administration of vaccines for engineering systemic immune responses to combat infectious diseases.

EXPERT OPINION

In-situ engineering of the cutaneous microenvironment using emerging skin-targeted vaccine delivery systems offers remarkable potential to develop diverse immunization strategies against pathogens. Mechanistic studies with standard correlates of vaccine efficacy will be important to compare innovative intracutaneous drug delivery strategies to each other and to existing clinical approaches. Cost-benefit analyses will be necessary for developing effective commercialization strategies. Significant involvement of industry and/or government will be imperative for successfully bringing novel skin-targeted vaccine delivery methods to market for their widespread use.

Lipid-based vaccine nanoparticles for induction of humoral immune responses against HIV-1 and SARS-CoV-2

The current health crisis of corona virus disease 2019 (COVID-19) highlights the urgent need for vaccine systems that can generate potent and protective immune responses. Protein vaccines are safe, but conventional approaches for protein-based vaccines often fail to elicit potent and long-lasting immune responses. Nanoparticle vaccines designed to co-deliver protein antigens and adjuvants can promote their delivery to antigen-presenting cells and improve immunogenicity. However, it remains challenging to develop vaccine nanoparticles that can preserve and present conformational epitopes of protein antigens for induction of neutralizing antibody responses. Here, we have designed a new lipid-based nanoparticle vaccine platform (NVP) that presents viral proteins (HIV-1 and SARS-CoV-2 antigens) in a conformational manner for induction of antigen-specific antibody responses. We show that NVP was readily taken up by dendritic cells (DCs) and promoted DC maturation and antigen presentation. NVP loaded with BG505.SOSIP.664 (SOSIP) or SARS-CoV-2 receptor-binding domain (RBD) was readily recognized by neutralizing antibodies, indicating the conformational display of antigens on the surfaces of NVP. Rabbits immunized with SOSIP-NVP elicited strong neutralizing antibody responses against HIV-1. Furthermore, mice immunized with RBD-NVP induced robust and long-lasting antibody responses against RBD from SARS-CoV-2. These results suggest that NVP is a promising platform technology for vaccination against infectious pathogens.

Subunit Nanovaccine with Potent Cellular and Mucosal Immunity for COVID-19

To combat the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, we formulated the S1 subunit of the virus with two adjuvants, amphiphilic adjuvant monophosphoryl lipid A for Toll-like receptor 4 and CpG oligodeoxynucleotide for Toll-like receptor 9, into cationic liposomes to produce a potent, safer, and translatable nanovaccine. The nanovaccine can efficiently elicit a humoral immune response and strong IgA antibodies in mice. The sera from the vaccinated mice significantly inhibit SARS-CoV-2 from infecting Vero cells. Moreover, relative to the free S1 with a traditional Alum adjuvant, the nanovaccine can elicit strong T-cell immunity by activating both CD4+ and CD8+ cells.

Potential Applications of Magnesium-Based Polymeric Nanocomposites Obtained by Electrospinning Technique

In the last few decades, the development of new electrospun materials with different morphologies and advanced multifunctional properties are strongly consolidated. There are several reviews that describe the processing, use and characterization of electrospun nanocomposites, however, based on our knowledge, no review on electrospun nanocomposites reinforced with nanoparticles (NPs) based on magnesium, Mg-based NPs, are reported. Therefore, in the present review, we focus attention on the fabrication of these promising electrospun materials and their potential applications. Firstly, the electrospinning technique and its main processing window-parameters are described, as well as some post-processing methods used to obtain Mg-based materials. Then, the applications of Mg-based electrospun nanocomposites in different fields are pointed out, thus taking into account the current trend in developing inorganic-organic nanocomposites to gradually satisfy the challenges that the industry generates. Mg-based electrospun nanocomposites are becoming an attractive field of research for environmental remediation (waste-water cleaning and air filtration) as well as for novel technical textiles. However, the mayor application of Mg-based electrospun materials is in the biomedical field, as pointed out. Therefore, this review aims to clarify the tendency in using electrospinning technique and Mg-based nanoparticles to huge development at industrial level in the near future.

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.

Multilamellar Vaccine Particle Elicits Potent Immune Activation with Protein Antigens and Protects Mice against Ebola Virus Infection

Recent outbreaks of emerging infectious diseases, such as Ebola virus disease (EVD), highlight the urgent need to develop effective countermeasures, including prophylactic vaccines. Subunit proteins derived from pathogens provide a safe source of antigens for vaccination, but they are often limited by their low immunogenicity. We have developed a multilamellar vaccine particle (MVP) system composed of lipid-hyaluronic acid multi-cross-linked hybrid nanoparticles for vaccination with protein antigens and demonstrate their efficacy against Ebola virus (EBOV) exposure. MVPs efficiently accumulated in dendritic cells and promote antigen processing. Mice immunized with MVPs elicited robust and long-lasting antigen-specific CD8⁺ and CD4⁺ T cell immune responses as well as humoral immunity. A single-dose vaccination with MVPs delivering EBOV glycoprotein achieved an 80% protection rate against lethal EBOV infection. These results suggest that MVPs offer a promising platform for improving recombinant protein-based vaccine approaches.

Development of a multiple-antigen protein fusion vaccine candidate that confers protection against Bacillus anthracis and Yersinia pestis

Bacillus anthracis and Yersinia pestis are zoonotic bacteria capable of causing severe and sometimes fatal infections in animals and humans. Although considered as diseases of antiquity in industrialized countries due to animal and public health improvements, they remain endemic in vast regions of the world disproportionally affecting the poor. These pathogens also remain a serious threat if deployed in biological warfare. A single vaccine capable of stimulating rapid protection against both pathogens would be an extremely advantageous public health tool. We produced multiple-antigen fusion proteins (MaF1 and MaF2) containing protective regions from B. anthracis protective antigen (PA) and lethal factor (LF), and from Y. pestis V antigen (LcrV) and fraction 1 (F1) capsule. The MaF2 sequence was also expressed from a plasmid construct (pDNA-MaF2). Immunogenicity and protective efficacy were investigated in mice following homologous and heterologous prime-boost immunization. Antibody responses were determined by ELISA and anthrax toxin neutralization assay. Vaccine efficacy was determined against lethal challenge with either anthrax toxin or Y. pestis. Both constructs elicited LcrV and LF-specific serum IgG, and MaF2 elicited toxin-neutralizing antibodies. Immunizations with MaF2 conferred 100% and 88% protection against Y. pestis and anthrax toxin, respectively. In contrast, pDNA-MaF2 conferred only 63% protection against Y. pestis and no protection against anthrax toxin challenge. pDNA-MaF2-prime MaF2-boost induced 75% protection against Y. pestis and 25% protection against anthrax toxin. Protection was increased by the molecular adjuvant CARDif. In conclusion, MaF2 is a promising multi-antigen vaccine candidate against anthrax and plague that warrants further investigation.

Anthrax and plague are ancient infectious diseases that continue to affect people living in poor, endemic regions and to threaten industrialized nations due to their potential use in biowarfare. Candidate vaccines need improvement to minimize non-desirable effects and increase their efficacy. The purpose of this work was to develop and evaluate a single subunit vaccine capable of conferring protection against Bacillus anthracis and Yersinia pestis. To this end, specific regions from their genome or key protective protein sequences from both microorganisms were combined to obtain either recombinant plasmids or recombinant proteins and tested as vaccine candidates in mice. The recombinant protein MaF2 induced specific antibody responses and afforded full and partial protection against Y. pestis and B. anthracis, respectively. Meanwhile, the DNA vaccine equivalent to MaF2 conferred only partial protection against Y. pestis, which increased when combined with an MaF2 protein boost. MaF2 emerged as a promising dual pathogen recombinant vaccine that warrants further investigation.

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.

Identification of FimH derivatives as adjuvant vaccinated with PAc that enhance protection against Streptcoccus mutans colonization

FimH is the adhesin of type I fimbriae expressed on Escherichia coli that can mediate specific adherence to host cells. High binding mutations in FimH are related to the adaptive evolution of bacteria. However, additional roles that these allelic variations may play remain elusive. To investigate novel biological functions of the mutations in FimH, we introduced four different variants of FimH by incorporating single amino acid substitutions at specific sites, namely A25P, G73R, A106, and T158P, respectively. In this study, adjuvant potential of FimH variants was evaluated by investigating their ability to trigger innate immune response to DC2.4 and adaptive immunity to improve immunological characteristics. The data revealed that purified A106 and T158P up-regulated the expression of co-stimulatory molecules critically involved in DC2.4 activation by interaction with TLR4, whereas A25P and G73R did not induce the phenotypic maturation of DC2.4. Besides, the culture of DC2.4 with A106 and T158P enhanced the release of cytokines and protein phagocytosis. When formulated with PAc, T158P elicited more robust PAc-specific IgG and IgA antibody responses compared to PBS, PAc and PAc+K12 groups and inhibited bacteria colonization. Collectively, the results confirmed that the T158P mutation located around the inter-domain interface of the protein induced a specific enhancement effect on adjuvant characteristics.

Vaccine nanoparticles displaying recombinant Ebola virus glycoprotein for induction of potent antibody and polyfunctional T cell responses

The recent outbreaks of Ebolavirus (EBOV) in West Africa underscore the urgent need to develop an effective EBOV vaccine. Here, we report the development of synthetic nanoparticles as a safe and highly immunogenic platform for vaccination against EBOV. We show that a large recombinant EBOV antigen (rGP) can be incorporated in a configurational manner into lipid-based nanoparticles, termed interbilayer-crosslinked multilamellar vesicles (ICMVs). The epitopes and quaternary structure of rGP were properly maintained on the surfaces of ICMVs formed either with or without nickel nitrilotriacetic acid (NTA)-functionalized lipids. When administered in mice, rGP-ICMVs without NTA-lipids efficiently generated germinal center B cells and polyfunctional T cells while eliciting robust neutralizing antibody responses. This study suggests the potential of vaccine nanoparticles as a delivery platform for configurational, multivalent display of large subunit antigens and induction of neutralizing antibody and T cell responses.

Dual TLR agonist nanodiscs as a strong adjuvant system for vaccines and immunotherapy

Recent studies have shown that certain combinations of Toll-like receptor (TLR) agonists can induce synergistic immune activation. However, it remains challenging to achieve such robust responses in vivo in a manner that is effective, facile, and amenable for clinical translation. Here, we show that MPLA, a TLR4 agonist, and CpG, a TLR9 agonist, can be efficiently co-loaded into synthetic high-density lipoprotein nanodiscs, forming a potent adjuvant system (ND-MPLA/CpG) that can be readily combined with a variety of subunit antigens, including proteins and peptides. ND-MPLA/CpG significantly enhanced activation of dendritic cells, compared with free dual adjuvants or nanodiscs delivering a single TLR agonist. Importantly, mice immunized with physical mixtures of protein antigens ND-MPLA/CpG generated strong humoral responses, including induction of IgG responses against protein convertase subtilisin/kexin 9 (PCSK9), leading to 17-30% reduction of the total plasma cholesterol levels. Moreover, ND-MPLA/CpG exerted strong anti-tumor efficacy in multiple murine tumor models. Compared with free adjuvants, ND-MPLA/CpG admixed with ovalbumin markedly improved antigen-specific CD8+ T cell responses by 8-fold and promoted regression of B16F10-OVA melanoma (P < 0.0001). Furthermore, ND-MPLA/CpG admixed with E7 peptide antigen elicited ~20% E7-specific CD8+ T cell responses and achieved complete regression of established TC-1 tumors in all treated animals. Taken together, our work highlights the simplicity, versatility, and potency of dual TLR agonist nanodiscs for applications in vaccines and cancer immunotherapy.

Potency of a Scalable Nanoparticulate Subunit Vaccine

Nanoparticulate vaccines can potentiate immune responses by site-specific drainage to lymph nodes (LNs). This approach may benefit from a nanoparticle engineering method with fine control over size and codelivery of antigen and adjuvant. Here, we applied the flash nanocomplexation (FNC) method to prepare nanovaccines via polyelectrolyte complexation of chitosan and heparin to coencapsulate the VP1 protein antigen from enterovirus 71, which causes hand-foot-mouth disease (HFMD), with tumor necrosis factor α (TNF) or CpG as adjuvants. FNC allows for reduction of the nanovaccine size to range from 90 to 130 nm with relatively narrower size distribution and a high payload capacity. These nanovaccines reached both proximal and distal LNs via subcutaneous injection and subsequently exhibited prolonged retention in the LNs. The codelivery induced strong immune activation toward a Th1 response in addition to a potent Th2 response, and conferred effective protection against lethal virus challenge comparable to that of an approved inactivated viral vaccine in mouse models of both passive and active immunization setting. In addition, these nanovaccines also elicited strong IgA titers, which may offer unique advantages for mucosal protection. This study addresses the issues of size control, antigen bioactivity retention, and biomanufacturing to demonstrate the translational potential of a subunit nanovaccine design.

Knowledge and attitudes towards Zika virus among medical students in King Abdulaziz University, Jeddah, Saudi Arabia

Zika Virus (ZIKV) and its associated consequences remain vital public health challenge of international concerns. The current study was done to assess knowledge and attitudes towards ZIKV and the factors associated with good knowledge among medical students in King Abdulaziz University, Jeddah. A cross-sectional study was conducted among 426 students. They were selected through multistage stratified random sample method, 2016. A validated, confidential, interviewing questionnaire contained 25 knowledge and 10 attitude items was used. Descriptive and inferential statistics were done. Results revealed that Facebook was the commonest source of ZIKV information. About half of the participants correctly identified mosquito bites and vertical route as ZIKV transmission modes. However, smaller percentages recognized the sexual and blood transmission modes. Calculations of knowledge score revealed that 77.5%, 15.0%, and 7.5% of the participants obtained poor, fair, and satisfactory scores, respectively. Age, educational year and attending ZIKV training were significantly associated with good knowledge (p<0.05). Concerning attitudes, about half of the participants agreed that ZIKV could add new burden on healthcare system of the affected countries. Most of participants were interested in learning more about ZIKV, emerging diseases and travel epidemiology. In conclusion, medical students had limited knowledge about ZIKV, and good attitudes towards learning about it. Conduction of ZIKV educational programs, and development of courses about emerging disease epidemiology are required.

Toward a Single-Dose Vaccination Strategy with Self-Encapsulating PLGA Microspheres

Poly(lactic-co-glycolic acid) (PLGA) microspheres have been widely examined for vaccine applications due to their attractive features of biocompatibility, biodegradability, ability to be internalized by antigen-presenting cells, and long-term antigen release. However, one of the major challenges for PLGA particle vaccines is the potential for antigen instability and loss of antigenicity and immunogenicity. To address this challenge, we have developed a new method of "self-healing" encapsulation in PLGA microspheres, where pre-made PLGA microspheres are loaded with protein antigens under aqueous conditions with minimal impact on their antigenicity and immunogenicity. In this report, we show that mice immunized with self-encapsulating PLGA microspheres in a prime-boost regimen generated significantly enhanced antigen-specific CD8α+ T cell and antibody responses, compared with mice immunized with free, soluble protein admixed with calcium phosphate gel, a widely used adjuvant. Furthermore, a single-dose of microspheres designed for >40 day sustained antigen release elicited robust cellular and humoral immune responses as efficiently as the prime-boost vaccinations with calcium phosphate gel. Overall, these results suggest excellent potential of our self-encapsulating PLGA microspheres as a vaccine platform for multiple-dose as well as single-dose vaccinations.

Biomaterial strategies for generating therapeutic immune responses

Biomaterials employed to raise therapeutic immune responses have become a complex and active field. Historically, vaccines have been developed primarily to fight infectious diseases, but recent years have seen the development of immunologically active biomaterials towards an expanding list of non-infectious diseases and conditions including inflammation, autoimmunity, wounds, cancer, and others. This review structures its discussion of these approaches around a progression from single-target strategies to those that engage increasingly complex and multifactorial immune responses. First, the targeting of specific individual cytokines is discussed, both in terms of delivering the cytokines or blocking agents, and in terms of active immunotherapies that raise neutralizing immune responses against such single cytokine targets. Next, non-biological complex drugs such as randomized polyamino acid copolymers are discussed in terms of their ability to raise multiple different therapeutic immune responses, particularly in the context of autoimmunity. Last, biologically derived matrices and materials are discussed in terms of their ability to raise complex immune responses in the context of tissue repair. Collectively, these examples reflect the tremendous diversity of existing approaches and the breadth of opportunities that remain for generating therapeutic immune responses using biomaterials.