Single low-dose un-adjuvanted HBsAg nanoparticle vaccine elicits robust, durable immunity

Nanotechnology in the Diagnosis and Treatment of Antibiotic-Resistant Infections

The development of antimicrobial resistance (AMR), along with the relative reduction in the production of new antimicrobials, significantly limits the therapeutic options in infectious diseases. Thus, novel treatments, especially in the current era, where AMR is increasing, are urgently needed. There are several ongoing studies on non-classical therapies for infectious diseases, such as bacteriophages, antimicrobial peptides, and nanotechnology, among others. Nanomaterials involve materials on the nanoscale that could be used in the diagnosis, treatment, and prevention of infectious diseases. This review provides an overview of the applications of nanotechnology in the diagnosis and treatment of infectious diseases from a clinician's perspective, with a focus on pathogens with AMR. Applications of nanomaterials in diagnosis, by taking advantage of their electrochemical, optic, magnetic, and fluorescent properties, are described. Moreover, the potential of metallic or organic nanoparticles (NPs) in the treatment of infections is also addressed. Finally, the potential use of NPs in the development of safe and efficient vaccines is also reviewed. Further studies are needed to prove the safety and efficacy of NPs that would facilitate their approval by regulatory authorities for clinical use.

Nanotechnology Platform for Advancing Vaccine Development against the COVID-19 Virus

The COVID-19 pandemic has had a profound impact on societies, public health, healthcare systems, and the world economy. With over 771 million people infected worldwide and a staggering death toll exceeding 6,960,783 as of 4 October 2023 (according to the World Health Organization), the urgency for a solution was paramount. Since the outbreak, the demand for immediate treatment for COVID-19 viral infection, as well as for effective vaccination against this virus, was soaring, which led scientists, pharmaceutical/biotech companies, government health agencies, etc., to think about a treatment strategy that could control and minimize this outbreak as soon as possible. Vaccination emerged as the most effective strategy to combat this infectious disease. For vaccination strategies, any conventional vaccine approach using attenuated live or inactivated/engineered virus, as well as other approaches, typically requires years of research and assessment. However, the urgency of the situation promoted a faster and more effective approach to vaccine development against COVID-19. The role of nanotechnology in designing, manufacturing, boosting, and delivering vaccines to the host to counter this virus was unquestionably valued and assessed. Several nanoformulations are discussed here in terms of their composition, physical properties, credibility, and applications in past vaccine development (as well as the possibility of using those used in previous applications for the generation of the COVID-19 vaccine). Controlling and eliminating the spread of the virus and preventing future recurrence requires a safe, tolerable, and effective vaccine strategy. In this review, we discuss the potential of nanoformulations as the basis for an effective vaccine strategy against COVID-19.

State-of-art high-performance Nano-systems for mutated coronavirus infection management: From Lab to Clinic

The emerging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants made emerging novel coronavirus diseases (COVID-19) pandemic/endemic/or both more severe and difficult to manage due to increased worry about the efficacy and efficiency of present preventative, therapeutic, and sensing measures. To deal with these unexpected circumstances, the development of novel nano-systems with tuneable optical, electrical, magnetic, and morphological properties can lead to novel research needed for (1) COVID-19 infection (anti-microbial systems against SARS-CoV-2), (2) early detection of mutated SARS-CoV-2, and (3) targeted delivery of therapeutics using nano-systems, i.e., nanomedicine. However, there is a knowledge gap in understanding all these nano-biotechnology potentials for managing mutated SARS-CoV-2 on a single platform. To bring up the aspects of nanotechnology to tackle SARS-CoV-2 variants related COVID-19 pandemic, this article emphasizes improvements in the high-performance of nano-systems to combat SARS-CoV-2 strains/variants with a goal of managing COVID-19 infection via trapping, eradication, detection/sensing, and treatment of virus. The potential of state-of-the-art nano-assisted approaches has been demonstrated as an efficient drug delivery systems, viral disinfectants, vaccine productive cargos, anti-viral activity, and biosensors suitable for point-of-care (POC) diagnostics. Furthermore, the process linked with the efficacy of nanosystems to neutralize and eliminate SARS-CoV-2 is extensively highligthed in this report. The challenges and opportunities associated with managing COVID-19 using nanotechnology as part of regulations are also well-covered. The outcomes of this review will help researchers to design, investigate, and develop an appropriate nano system to manage COVID-19 infection, with a focus on the detection and eradication of SARS-CoV-2 and its variants. This article is unique in that it discusses every aspect of high-performance nanotechnology for ideal COVID pandemic management.

Vaccines platforms and COVID-19: what you need to know

BACKGROUND

The novel SARS-CoV-2, responsible for the COVID-19 pandemic, is the third zoonotic coronavirus since the beginning of the 21 first century, and it has taken more than 6 million human lives because of the lack of immunity causing global economic losses. Consequently, developing a vaccine against the virus represents the fastest way to finish the threat and regain some "normality."

OBJECTIVE

Here, we provide information about the main features of the most important vaccine platforms, some of them already approved, to clear common doubts fostered by widespread misinformation and to reassure the public of the safety of the vaccination process and the different alternatives presented.

METHODS

Articles published in open access databases until January 2022 were identified using the search terms "SARS-CoV-2," "COVID-19," "Coronavirus," "COVID-19 Vaccines," "Pandemic," COVID-19, and LMICs or their combinations.

DISCUSSION

Traditional first-generation vaccine platforms, such as whole virus vaccines (live attenuated and inactivated virus vaccines), as well as second-generation vaccines, like protein-based vaccines (subunit and viral vector vaccines), and third-generation vaccines, such as nanoparticle and genetic vaccines (mRNA vaccines), are described.

CONCLUSIONS

SARS-CoV-2 sequence information obtained in a record time provided the basis for the fast development of a COVID-19 vaccine. The adaptability characteristic of the new generation of vaccines is changing our capability to react to emerging threats to future pandemics. Nevertheless, the slow and unfair distribution of vaccines to low- and middle-income countries and the spread of misinformation are a menace to global health since the unvaccinated will increase the chances for resurgences and the surge of new variants that can escape the current vaccines.

Use of Nanomaterials for Diagnosis and Treatment: The Advancement of Next-Generation Antiviral Therapy

Globally, viral illness propagation is the leading cause of morbidity and death, causing wreaking havoc on socioeconomic development and health care systems. The rise of infected individuals has outpaced the existing critical care facilities. Early and sophisticated methods are desperately required in this respect to halt the spread of the infection. Therefore, early detection of infectious agents and an early treatment approach may help minimize viral outbreaks. Conventional point-of-care diagnostic techniques such as computed tomography scan, quantitative real time polymerase chain reaction (qRT-PCR), X-ray, and immunoassay are still deemed valuable. However, the labor demanding, low sensitivity, and complex infrastructure needed for these methods preclude their use in distant areas. Nanotechnology has emerged as a potentially transformative technology due to its promise as an effective theranostic platform for diagnosing and treating viral infection, circumventing the limits of traditional techniques. Their unique physical and chemical characteristics make nanoparticles (NPs) advantageous for drug delivery platforms due to their size, encapsulation efficiency, improved bioavailability, effectiveness, immunogenicity, and antiviral response. This study discusses the recent research on nanotechnology-based treatments designed to combat new viruses.

Recent advances on chitosan as an adjuvant for vaccine delivery

Chitosan (CS) is a natural polymer derived from chitin that has wide applications in drugs, vaccines, and antigen delivery. The distinctive mucoadhesive, biocompatibility, biodegradable, and less toxic properties of chitosan compared to the currently used vaccine adjuvants made it a promising candidate for use as an adjuvant/carrier in vaccine delivery. In addition, chitosan exhibits intrinsic immunomodulating properties making it a suitable adjuvant in preparing vaccines delivery systems. Nanoparticles (NPs) of chitosan and its derivatives loaded with antigen have been shown to induce cellular and humoral responses. Versatility in the physicochemical properties of chitosan can provide an excellent opportunity to engineer antigen-specific adjuvant/delivery systems. This review discusses the recent advances of chitosan and its derivatives as adjuvants in vaccine deliveryand the published literature in the last fifteen years. The impact of physicochemical properties of chitosan on vaccine formulation has been described in detail. Applications of chitosan and its derivatives, their physicochemical properties, and mechanisms in enhancing immune responses have been discussed. Finally, challenges and future aspects of chitosan use has been pointed out.

Current view on novel vaccine technologies to combat human infectious diseases

Inactivated and live attenuated vaccines have improved human life and significantly reduced morbidity and mortality of several human infectious diseases. However, these vaccines have faults, such as reactivity or suboptimal efficacy and expensive and time-consuming development and production. Additionally, despite the enormous efforts to develop vaccines against some infectious diseases, the traditional technologies have not been successful in achieving this. At the same time, the concerns about emerging and re-emerging diseases urge the need to develop technologies that can be rapidly applied to combat the new challenges. Within the last two decades, the research of vaccine technologies has taken several directions to achieve safe, efficient, and economic platforms or technologies for novel vaccines. This review will give a brief overview of the current state of the novel vaccine technologies, new vaccine candidates in clinical trial phases 1-3 (listed by European Medicines Agency (EMA) and Food and Drug Administration (FDA)), and vaccines based on the novel technologies which have already been commercially available (approved by EMA and FDA) with the special reference to pandemic COVID-19 vaccines. KEY POINTS: • Vaccines of the new generation follow the minimalist strategy. • Some infectious diseases remain a challenge for the vaccine development. • The number of new vaccine candidates in the late phase clinical trials remains low.

Carbohydrates-based diagnosis, prophylaxis and treatment of infectious diseases: Special emphasis on COVID-19

COVID-19 pandemic is taking a dangerous turn due to unavailability of approved and effective vaccines and therapy. Currently available diagnostic techniques are time-consuming, expensive, and maybe impacted by the mutations produced in the virus. Therefore, investigation of novel, rapid, and economic diagnosis techniques, prophylactic vaccines and targeted efficacious drug delivery systems as treatment strategy is imperative. Carbohydrates are essential biomolecules which also act as markers in the realization of immune systems. Moreover, they exhibit antiviral, antimicrobial, and antifungal properties. Carbohydrate-based vaccines and therapeutics including stimuli sensitive systems can be developed successfully and used effectively to fight COVID-19. Thus, carbohydrate-based diagnostic, prophylactic and therapeutic alternatives could be promising to defeat COVID-19 propitiously. Morphology of SARS-CoV-2 and its relevance in devising combat strategies has been discussed. Carbohydrate-based approaches for tackling infectious diseases and their importance in the design of various diagnostic and treatment modalities have been reviewed.

Applications of nanomaterials in COVID-19 pandemic

The novel coronavirus 2019 (COVID-19) pandemic represents one of the biggest global health threats in the last two decades, so researchers around the world are searching for solutions and treatments for COVID-19. At the time of writing, there are no specific drugs that have demonstrated suitable effectiveness in treating COVID-19. The current challenge involves designing tools for the prevention, rapid and accurate diagnosis, drug delivery, and effective treatment of this novel coronavirus. In this short review, we discuss how nanotechnology offers new ways to combat COVID-19, and how nanomaterials can be applied to control the COVID-19 outbreak. We also summarize relevant studies regarding the use of nanomaterials for preventing viral spread, preparing vaccines, and diagnosing coronavirus, as well as studies that show how nanoparticles can be used as drug delivery systems for the treatment of viral infections. Research on nanotechnology-based diagnosis, drug delivery, and antiviral therapy is currently in the early stages. However, the unique chemical properties of some nanomaterials highlight the broad prospect of nanomaterials in the future, and we propose that they will play an important role in the fight against COVID-19.

GRAPHICAL ABSTRACT

Carbohydrate-containing nanoparticles as vaccine adjuvants

Introduction: Adjuvants are essential to vaccines for immunopotentiation in the elicitation of protective immunity. However, classical and widely used aluminum-based adjuvants have limited capacity to induce cellular response. There are increasing needs for appropriate adjuvants with improved profiles for vaccine development toward emerging pathogens. Carbohydrate-containing nanoparticles (NPs) with immunomodulatory activity and particulate nanocarriers for effective antigen presentation are capable of eliciting a more balanced humoral and cellular immune response.Areas covered: We reviewed several carbohydrates with immunomodulatory properties. They include chitosan, β-glucan, mannan, and saponins, which have been used in vaccine formulations. The mode of action, the preparation methods, characterization of these carbohydrate-containing NPs and the corresponding vaccines are presented.Expert opinion: Several carbohydrate-containing NPs have entered the clinical stage or have been used in licensed vaccines for human use. Saponin-containing NPs are being evaluated in a vaccine against SARS-CoV-2, the pathogen causing the on-going worldwide pandemic. Vaccines with carbohydrate-containing NPs are in different stages of development, from preclinical studies to late-stage clinical trials. A better understanding of the mode of action for carbohydrate-containing NPs as vaccine carriers and as immunostimulators will likely contribute to the design and development of new generation vaccines against cancer and infectious diseases.

Novel Vaccine Technologies in Veterinary Medicine: A Herald to Human Medicine Vaccines

The success of inactivated and live-attenuated vaccines has enhanced livestock productivity, promoted food security, and attenuated the morbidity and mortality of several human, animal, and zoonotic diseases. However, these traditional vaccine technologies are not without fault. The efficacy of inactivated vaccines can be suboptimal with particular pathogens and safety concerns arise with live-attenuated vaccines. Additionally, the rate of emerging infectious diseases continues to increase and with that the need to quickly deploy new vaccines. Unfortunately, first generation vaccines are not conducive to such urgencies. Within the last three decades, veterinary medicine has spearheaded the advancement in novel vaccine development to circumvent several of the flaws associated with classical vaccines. These third generation vaccines, including DNA, RNA and recombinant viral-vector vaccines, induce both humoral and cellular immune response, are economically manufactured, safe to use, and can be utilized to differentiate infected from vaccinated animals. The present article offers a review of commercially available novel vaccine technologies currently utilized in companion animal, food animal, and wildlife disease control.

Nano-adjuvant based on silk fibroin for the delivery of recombinant hepatitis B surface antigen

Nanotechnology has a vital role in vaccine development. Nano-adjuvants, as robust delivery systems, could stimulate immune responses. Using nanoparticles (NPs) in vaccine formulations enhances the target delivery, immunogenicity, and stability of the antigens. Herein, silk fibroin nanoparticles (SFNPs) were used as a nano-adjuvant for delivering recombinant hepatitis B surface antigen (HBsAg). HBsAg was loaded physically and chemically on the surface of SFNPs. The HBsAg-loaded SFNPs had a spherical morphology. The in vitro release studies showed that HBsAg had a continuous and slow release from SFNPs during 56 days. During this time, ∼45.6% and 34.1% HBsAg was released from physical-SFNPs and chemical-SFNPs, respectively. HBsAg-loaded SFNPs were also stable for six months with slight changes in the size, surface charge, and morphology. The results of circular dichroism (CD) and fluorescence spectroscopy indicated that the released HBsAg preserved the native secondary and tertiary structures. The quantitative cellular uptake study also showed that physical-SFNPs were taken up more into J774A.1 macrophage cells than chemical-SFNPs. After 28 and 56 days post-injection, the immunogenicity studies showed that the specific total IgG, IgG1, and IgG2a levels against HBsAg were significantly higher in the physically loaded group than in the chemically loaded group and commercial hepatitis B vaccine. IgG2a levels were detected only in mice immunized with physical-SFNPs. However, the low levels of IL-4 and IFN-γ were produced in all vaccinated groups and differences in mean values were not significant compared with control groups. Results indicated an improvement in the levels of anti-HBsAg IgG in mice immunized with the physical-SFNPs group compared to other groups.

Chitosan-Based Nanoparticles Against Viral Infections

Viral infections, in addition to damaging host cells, can compromise the host immune system, leading to frequent relapse or long-term persistence. Viruses have the capacity to destroy the host cell while liberating their own RNA or DNA in order to replicate within additional host cells. The viral life cycle makes it challenging to develop anti-viral drugs. Nanotechnology-based approaches have been suggested to deal effectively with viral diseases, and overcome some limitations of anti-viral drugs. Nanotechnology has enabled scientists to overcome the challenges of solubility and toxicity of anti-viral drugs, and can enhance their selectivity towards viruses and virally infected cells, while preserving healthy host cells. Chitosan is a naturally occurring polymer that has been used to construct nanoparticles (NPs), which are biocompatible, biodegradable, less toxic, easy to prepare, and can function as effective drug delivery systems (DDSs). Furthermore, chitosan is Generally Recognized as Safe (GRAS) by the US Food and Drug Administration (U.S. FDA). Chitosan NPs have been used in drug delivery by the oral, ocular, pulmonary, nasal, mucosal, buccal, or vaginal routes. They have also been studied for gene delivery, vaccine delivery, and advanced cancer therapy. Multiple lines of evidence suggest that chitosan NPs could be used as new therapeutic tools against viral infections. In this review we summarize reports concerning the therapeutic potential of chitosan NPs against various viral infections.

Polymeric nanoparticle vaccines to combat emerging and pandemic threats

Subunit vaccines are more advantageous than live attenuated vaccines in terms of safety and scale-up manufacture. However, this often comes as a trade-off to their efficacy. Over the years, polymeric nanoparticles have been developed to improve vaccine potency, by engineering their physicochemical properties to incorporate multiple immunological cues to mimic pathogenic microbes and viruses. This review covers recent advances in polymeric nanostructures developed toward particulate vaccines. It focuses on the impact of microbe mimicry (e.g. size, charge, hydrophobicity, and surface chemistry) on modulation of the nanoparticles’ delivery, trafficking, and targeting antigen-presenting cells to elicit potent humoral and cellular immune responses. This review also provides up-to-date progresses on rational designs of a wide variety of polymeric nanostructures that are loaded with antigens and immunostimulatory molecules, ranging from particles, micelles, nanogels, and polymersomes to advanced core-shell structures where polymeric particles are coated with lipids, cell membranes, or proteins.

Nanotechnology-based promising strategies for the management of COVID-19: current development and constraints

INTRODUCTION

COVID-19 pandemic has been declared as a global emergency by the World Health Organization which has mounted global pressure on the healthcare system. The design and development of rapid tests for the precise and early detection of infection are urgently needed to detect the disease and also for bulk screening of infected persons. The traditional drugs moderately control the symptoms, but so far, no specific drug has been discovered. The prime concern is to device novel tools for rapid and precise diagnosis, drug delivery, and effective therapies for coronavirus. In this context, nanotechnology offers novel ways to fight against COVID-19.

AREA COVERED

This review includes the use of nanomaterials for the control of COVID-19. The tools for diagnosis of coronavirus, nano-based vaccines, and nanoparticles as a drug delivery system for the treatment of virus infection have been discussed. The toxicity issues related to nanoparticles have also been addressed.

EXPERT OPINION

The research on nanotechnology-based diagnosis, drug delivery, and antiviral therapies is at a preliminary stage. The antiviral nanomedicine therapies are cost-effective and with high quality. Nanoparticles are a promising tool for prevention, diagnosis, antiviral drug delivery, and therapeutics, which may open up new avenues in the treatment of COVID-19.

Nanomaterials and Nanotechnology-Associated Innovations against Viral Infections with a Focus on Coronaviruses

Viral infections have recently emerged not only as a health threat to people but rapidly became the cause of universal fatality on a large scale. Nanomaterials comprising functionalized nanoparticles (NPs) and quantum dots and nanotechnology-associated innovative detection methods, vaccine design, and nanodrug production have shown immense promise for interfacing with pathogenic viruses and restricting their entrance into cells. These viruses have been scrutinized using rapid diagnostic detection and therapeutic interventional options against the caused infections including vaccine development for prevention and control. Coronaviruses, namely SARS-CoV, MERS-CoV, and SARS-CoV-2, have endangered human life, and the COVID-19 (caused by SARS-CoV-2) outbreak has become a perilous challenge to public health globally with huge accompanying morbidity rates. Thus, it is imperative to expedite the drug and vaccine development efforts that would help mitigate this pandemic. In this regard, smart and innovative nano-based technologies and approaches encompassing applications of green nanomedicine, bio-inspired methods, multifunctional bioengineered nanomaterials, and biomimetic drug delivery systems/carriers can help resolve the critical issues regarding detection, prevention, and treatment of viral infections. This perspective review expounds recent nanoscience advancements for the detection and treatment of viral infections with focus on coronaviruses and encompasses nano-based formulations and delivery platforms, nanovaccines, and promising methods for clinical diagnosis, especially regarding SARS-CoV-2.

Chitosan nanoparticles as a delivery platform for neurotoxin II from Androctonus australis hector scorpion venom: Assessment of toxicity and immunogenicity

In recent years, biodegradable polymers based nanoparticles received high interest for the development of vaccine delivery vehicles. In this study, chitosan nanoparticles encapsulating Aah II toxin (AahII-CNPs) isolated from Androctonus australis hector venom, were investigated as vaccine delivery system. Particles obtained by ionotropic gelation were characterized for their size, surface charge, morphology and toxin release profile from Aah II-CNPs. Toxin-nanoparticles interactions were assessed by Fourier Transform Infrared Spectrometry and X-Ray Diffraction. An immunization protocol was designed in mice to investigate anti-toxin immunity and the protective status induced by different Aah II immune formulations. Unloaded chitosan nanoparticles presenting a spherical shape and smooth surface, were characterized by a size of 185 nm, a dispersion index (PDI) of 0.257 and a zeta potential of +34.6 mV. Aah II toxin was successfully entrapped into chitosan nanoparticles as revealed by FTIR and XRD data. Entrapment efficiency (EE) and Loading capacity (LC) were respectively of 96.66 and 33.5%. Aah II-CNPs had a diameter of 208 nm, a PDI of 0.23 and a zeta potential of +30 mV. Encapsulation of Aah II reduced its toxicity and protected mice until 10 LD₅₀. Mice were immunized via a dual prime-boost scheme. Nanoentrapped Aah II immunogen elicited systemic innate and humoral immune responses as well as local spleen parenchyma hyperplasic alterations. Aah II-CNPs immunized mice withstood high lethal doses of native Aah II, one-month post-boost inoculation. This study provided encouraging and promising results for the development of preventive therapies against scorpion envenoming mainly for the populations at-risk.

Nanoparticle-based vaccines

Infectious diseases are the tip of the iceberg in the economic burden of the developing countries, due to the resistance of the pathogens to antibiotics and the lack of vaccines. The vaccines have become a big challenge in the last decades, where the attention has been focused on scientific challenges such as new vaccine development and adjuvants or delivery systems. The classical vaccines were developed from live-attenuated or killed organisms, such as influenza, smallpox, and BCG, as well as subunits such as Hepatitis B. The attenuated vaccines carry the risk of regaining their pathogenicity under immunosuppression conditions. The development of subunit vaccines without risk are considered as an essential need in combination with adequate delivery systems to obtain desired cell and humoral immune responses against infectious diseases. In the last decades, the use of nanoparticles as a delivery system in vaccines has received special attention to improve vaccine efficacy. These nanoparticles could be composed of lipids, metal and nonmetal inorganics, several polymers, and virus-like particles, which have been tested in research; some of them have already been approved for human and animal use. The characteristics of the nanoparticles have allowed targeting desired antigen-presenting cells to improve immunization strategies to induce protection. The main characteristics of the nanoparticles are to protect the antigens from early proteolytic degradation, control antigen release, and help antigen uptake and processing by antigen-presenting cells, and they should be safe for human and veterinary use. In addition, the nanoparticles could be modified in their physicochemical properties to target specific cells and improve vaccine efficacy. This chapter focuses on the nanoparticle-based vaccine formulations and the approaches used to realize efficient delivery of vaccines in order to induce host protective immunity against infectious diseases.

Single dose HBsAg CS-γ-PGA nanogels induce potent protective immune responses against HBV infection

Hepatitis B virus (HBV) infection is a severe threat to public health, which can be prevented by prophylactic vaccination. Here, we tested nanogels carriers in the prophylactic effect of hepatitis B surface antigen (HBsAg) vaccine. HBsAg nanogels (Ng) were prepared using chitosan (CS) and poly-γ-glutamic acid (γ-PGA). Positively charged Ng (+) and negatively charged Ng (-) were prepared by adjusting the CS and γ-PGA proportion. Dendritic cells (DCs) maturation in mice immunized with HBsAg Ng (+) and HBsAg Ng (-) could be augmented in response to pAAV/HBV1.2 plasmid challenge. Single-dose immunization with HBsAg Ng (+) induced HBsAg specific-antibodies. HBsAg Ng (+) immunized mice cleared HBsAg and restored anti-HBs production after pAAV/HBV1.2 plasmid challenge. Single-dose HBsAg Ng (+) induced humoral and cellular immunity, and could induce effector memory T cells. Single-dose HBsAg Ng (-) favored the induction of cellular immunity, and induced central memory T cells and effector memory T cells. However, HBsAg elimination was similar between HBsAg Ng (+)- and HBsAg Ng (+) plus HBsAg Ng (-)-immunized mice. Zeta potential measurements showed that HBsAg Ng (+) were more stable than HBsAg Ng (-). Therefore, Ng (+) are desirable HBsAg prophylactic vaccine carriers, providing long-term protection against HBV, and are a good choice to study and apply weakly immunostimulatory antigens.

Chitosan-Poly (I:C)-PADRE Based Nanoparticles as Delivery Vehicles for Synthetic Peptide Vaccines

The safety and precision of peptide antigens has prompted the search for adjuvants capable of increasing the immune response against these intrinsically poorly immunogenic antigens. The integration of both immunostimulants and peptide antigens within nanometric delivery systems for their co-delivery to immune cells is a promising vaccination strategy. With this in mind, the potential synergistic effect of the immunostimulant poly (I:C) (pIC) and a T-Helper peptide (PADRE), integrated into a chitosan (CS) based nanostructure, was explored. The value of this nanostructured combination of materials was assessed for a peptide antigen (1338aa) derived from the HPV-16 L2 protein. These nanoparticles, produced by ionic gelation technique, exhibited a nanometric size (<300 nm), a high positive surface charge (>40 mV) and high pIC association efficiency (>96%). They also showed capacity for the association of both the 1338aa and PADRE peptides. The influence of the presence of pIC and PADRE in the nanocomposition, as well as that of the peptide presentation form (encapsulated versus surface adsorbed) on the antibody induction was evaluated in a preliminary in vivo study. The data obtained highlights the possibility to engineer nanoparticles through the rational combination of a number of adjuvant molecules together with the antigen.

Single-injection vaccines: Progress, challenges, and opportunities

Currently, vaccination is the most efficient and cost-effective medical treatment for infectious diseases; however, each year 10 million infants remain underimmunized due to current vaccination schedules that require multiple doses to be administered across months or years. These dosing regimens are especially challenging in the developing world where limited healthcare access poses a major logistical barrier to immunization. Over the past four decades, researchers have attempted to overcome this issue by developing single-administration vaccines based on controlled-release antigen delivery systems. These systems can be administered once, but release antigen over an extended period of time to elicit both primary and secondary immune responses resulting in antigen-specific immunological memory. Unfortunately, unlike controlled release systems for drugs, single-administration vaccines have yet to be commercialized due to poor antigen stability and difficulty in obtaining unconventional release kinetics. This review discusses the current state of single-administration vaccination, challenges delaying the development of these vaccines, and potential strategies for overcoming these challenges.

Nanoengineering of vaccines using natural polysaccharides

Currently, there are over 70 licensed vaccines, which prevent the pathogenesis of around 30 viruses and bacteria. Nevertheless, there are still important challenges in this area, which include the development of more active, non-invasive, and thermo-resistant vaccines. Important biotechnological advances have led to safer subunit antigens, such as proteins, peptides, and nucleic acids. However, their limited immunogenicity has demanded potent adjuvants that can strengthen the immune response. Particulate nanocarriers hold a high potential as adjuvants in vaccination. Due to their pathogen-like size and structure, they can enhance immune responses by mimicking the natural infection process. Additionally, they can be tailored for non-invasive mucosal administration (needle-free vaccination), and control the delivery of the associated antigens to a specific location and for prolonged times, opening room for single-dose vaccination. Moreover, they allow co-association of immunostimulatory molecules to improve the overall adjuvant capacity.

The natural and ubiquitous character of polysaccharides, together with their intrinsic immunomodulating properties, their biocompatibility, and biodegradability, justify their interest in the engineering of nanovaccines. In this review, we aim to provide a state-of-the-art overview regarding the application of nanotechnology in vaccine delivery, with a focus on the most recent advances in the development and application of polysaccharide-based antigen nanocarriers.

Next generation vaccines: single-dose encapsulated vaccines for improved global immunisation coverage and efficacy

OBJECTIVES

Vaccination is considered the most successful health intervention; yet incomplete immunisation coverage continues to risk outbreaks of vaccine preventable diseases worldwide. Vaccination coverage improvement through a single-dose prime-boost technology would revolutionise modern vaccinology, impacting on disease prevalence, significantly benefiting health care and lowering economic burden of disease.

KEY FINDINGS

Over the past 30 years, there have been efforts to develop a single-dose delayed release vaccine technology that could replace the repeated prime-boost immunisations required for many current vaccines. Biocompatible polymers have been employed to encapsulate model vaccines for delayed delivery in vivo, using either continuous or pulsed release. Biomaterial considerations, safety aspects, particle characteristics and immunological aspects of this approach are discussed in detail.

SUMMARY

Despite many studies showing the feasibility of vaccine encapsulation for single-dose prime-boost administration, none have been translated into convincing utility in animal models or human trials. Further development of the encapsulation technology, through optimising the particle composition, formulation, antigen loading efficacy and stability, could lead to the application of this important approach in vaccine deployment. If successful, this would provide a solution to better global vaccination coverage through a reduction in the number of immunisations needed to achieve protection against infectious diseases. This review provides an overview of single-dose vaccination in the context of today's vaccine needs and is derived from a body of literature that has not been reviewed for over a decade.

Fabrication of nanoadjuvant with poly-ε-caprolactone (PCL) for developing a single-shot vaccine providing prolonged immunity

Purpose

The aim of the study was to load a model antigen, tetanus toxoid (TT), in poly-ε-caprolactone nanoparticles (PCL NPs) of two size ranges, ie, mean 61.2 nm (small) and 467.6 nm (large), and study its effect on macrophage polarization as well as antigen presentation in human monocyte-derived macrophages in vitro, along with humoral and cell-mediated immune (CMI) response generated in Swiss albino mice following immunization with the TT-loaded NPs.

Materials and methods

PCL NPs were synthesized by solvent evaporation. The antigen-loaded PCL NPs were characterized for size, zeta potential, and protein-release kinetics. Swiss albino mice were immunized with the antigen-loaded PCL NPs. Flow cytometry was used to quantify interferon-γ- and interleukin-4-secreting cluster of differentiation (CD)4⁺ and CD8⁺ T cells in the spleen, and enzyme-linked immunosorbent assay was used to quantify anti-TT antibody levels in the serum of immunized mice.

Results

Small PCL NPs generated an M1/M2 type polarization of human blood monocyte-derived macrophages and T helper (Th)1/Th2 polarization of autologous CD4⁺ T cells. Efficient CD8⁺ T-cell responses were also elicited. Large PCL NPs failed to cause any type of macrophage polarization. They did not elicit efficient CD8⁺ T-cell responses.

Conclusion

TT-loaded small PCL NPs were able to generate persistent and strong CMI and humoral responses against TT 2 months after single injection in mice without booster dose. This biodegradable nanoadjuvant system may help to develop single-shot immunization for prolonged immunity without booster doses. The capability of enhanced CMI response may have high translational potential for immunization against intracellular infection.