Vaccines, new opportunities for a new society

The expanding role of mass spectrometry in the field of vaccine development

Biological mass spectrometry has evolved as a core analytical technology in the last decade mainly because of its unparalleled ability to perform qualitative as well as quantitative profiling of enormously complex biological samples with high mass accuracy, sensitivity, selectivity and specificity. Mass spectrometry-based techniques are also routinely used to assess glycosylation and other post-translational modifications, disulfide bond linkage, and scrambling as well as for the detection of host cell protein contaminants in the field of biopharmaceuticals. The role of mass spectrometry in vaccine development has been very limited but is now expanding as the landscape of global vaccine development is shifting towards the development of recombinant vaccines. In this review, the role of mass spectrometry in vaccine development is presented, some of the ongoing efforts to develop vaccines for diseases with global unmet medical need are discussed and the regulatory challenges of implementing mass spectrometry techniques in a quality control laboratory setting are highlighted.

Vaccination against Allergy: A Paradigm Shift?

Since the discovery that IgE antibodies mediate allergy, decades of research have unraveled complex mechanisms associated with conventional immunotherapy and the vital protagonists that shape 'immune tolerance' to allergens. Debate exists on what should constitute the dominant effector mechanism in driving rational drug designs for next-generation immunotherapies. As vaccine technology continues to advance, the development of novel vaccines in this area of continued medical need might stand on a threshold of breakthrough inspired by experiments by Dunbar on the passive vaccination of allergic animals more than 100 years ago. In this opinion article, we discuss both novel insights into IgG antibodies as the principle effector modality induced by specific immunotherapy and advances in antigen-carrier design that may catapult allergy treatment into our modern world.

Ageing, age-related diseases and oxidative stress: What to do next?

Among other mechanisms, oxidative stress has been postulated to play an important role in the rate of ageing. Oxidative damage contributes to the hallmarks of ageing and essential components in pathological pathways which are thought to drive multiple age-related diseases. Nonetheless, results from studies testing the hypothesis of oxidative stress in ageing and diseases showed controversial results. While observational studies mainly found detrimental effects of high oxidative stress levels on disease status, randomized clinical trials examining the effect of antioxidant supplementation on disease status generally showed null effects. However, re-evaluations of these counterinitiative observations are required considering the lack of reliability and specificity of traditionally used biomarkers for measuring oxidative stress. To facilitate these re-evaluations, this review summarizes the basic knowledge of oxidative stress and the present findings regarding the role of oxidative damage in ageing and age-related diseases. Meanwhile, two approaches are highlighted, namely proper participants selection, together with the development of reliable biomarkers. We propose that oxidized vitamin E metabolites may be used to accurately monitor individual functional antioxidant level, which might serve as promising key solutions for future elucidating the impact of oxidative stress on ageing and age-related diseases.

Recombinant PBP2a of methicillin-resistant S. aureus formulation in Alum and Montanide ISA266 adjuvants induced cellular and humoral immune responses with protection in Balb/C mice

Staphylococcus aureus is an important cause of both hospital and community acquired infections worldwide. S.aureus can develop multidrug resistance; thus, immunotherapy can be a rational alternative. High level β-lactam resistance of S. aureus has been attributed to the penicillin binding protein 2a (PBP2a). In this study, we assessed the immunogenicity and protectivity of PBP2a formulated in Montanide ISA266 and Alum adjuvants. Recombinant PBP2a with a molecular weight of approximately 13 kDa was expressed and purified by nickel-nitrilotriacetic acid (NI-NTA) affinity chromatography and characterized by SDS-PAGE and Western blot. To investigate the immunogenicity and protective effects of recombinant protein, 20 μg of r-PBP2a in various formulations were subcutaneously injected in different groups. Two booster vaccinations were carried out in two-week intervals and blood samples were collected two weeks after each injection. To determine the type of induced immune response, sera and splenocytes were analyzed by ELISA for total IgG and isotypes (IgG1 and IgG2a) and cytokine secretion (IFN-γ, IL-4, IL-17 and TNF-α), respectively. Three weeks following the last immunization, experimental mice were challenged with 5 × 10⁸ CFU of bacteria intraperitoneally and mortality rate and bacterial load were assessed. Interestingly, analysis of humoral immune responses revealed that administration of r-PBP2a with Montanide ISA266 significantly increased specific IgG responses and also IgG1 isotype compared to alum-adjuvanted vaccine group. Also, r-PBP2a formulation with alum and MontanideISA266 adjuvants raised IFN-γ, IL-4, IL-17 cytokines secretion, and protectivity following experimental challenge. The results of the present study provide evidences for immunogenicity and protectivity of PBP2a protein as a vaccine candidate.

In silico Design of an Epitope-Based Vaccine Ensemble for Chagas Disease

Trypanosoma cruzi infection causes Chagas disease, which affects 7 million people worldwide. Two drugs are available to treat it: benznidazole and nifurtimox. Although both are efficacious against the acute stage of the disease, this is usually asymptomatic and goes undiagnosed and untreated. Diagnosis is achieved at the chronic stage, when life-threatening heart and/or gut tissue disruptions occur in ~30% of those chronically infected. By then, the drugs' efficacy is reduced, but not their associated high toxicity. Given current deficiencies in diagnosis and treatment, a vaccine to prevent infection and/or the development of symptoms would be a breakthrough in the management of the disease. Current vaccine candidates are mostly based on the delivery of single antigens or a few different antigens. Nevertheless, due to the high biological complexity of the parasite, targeting as many antigens as possible would be desirable. In this regard, an epitope-based vaccine design could be a well-suited approach. With this aim, we have gone through publicly available databases to identify T. cruzi epitopes from several antigens. By means of a computer-aided strategy, we have prioritized a set of epitopes based on sequence conservation criteria, projected population coverage of Latin American population, and biological features of their antigens of origin. Fruit of this analysis, we provide a selection of CD8⁺ T cell, CD4⁺ T cell, and B cell epitopes that have <70% identity to human or human microbiome protein sequences and represent the basis toward the development of an epitope-based vaccine against T. cruzi.

Identification of lipid A deacylase as a novel, highly conserved and protective antigen against enterohemorrhagic Escherichia coli

Enterohemorrhagic E. coli (EHEC) is a major cause of large outbreaks worldwide associated with hemorrhagic colitis and hemolytic uremic syndrome. While vaccine development is warranted, a licensed vaccine, specific for human use, against EHEC is not yet available. In this study, the reverse vaccinology approach combined with genomic, transcriptional and molecular epidemiology data was applied on the EHEC O157:H7 genome to select new potential vaccine candidates. Twenty-four potential protein antigens were identified and one of them (MC001) was successfully expressed onto Generalized Modules for Membrane Antigens (GMMA) delivery system. GMMA expressing this vaccine candidate was immunogenic, raising a specific antibody response. Immunization with the MC001 candidate was able to reduce the bacterial load of EHEC O157:H7 strain in feces, colon and caecum tissues after murine infection. MC001 is homologue to lipid A deacylase enzyme (LpxR), and to our knowledge, this is the first study describing it as a potential vaccine candidate. Gene distribution and sequence variability analysis showed that MC001 is present and conserved in EHEC and in enteropathogenic E. coli (EPEC) strains. Given the high genetic variability among and within E. coli pathotypes, the identification of such conserved antigen suggests that its inclusion in a vaccine might represent a solution against major intestinal pathogenic strains.

Physical and chemical profiles of nanoparticles for lymphatic targeting

Nanoparticles (NPs) have been gaining prominence as delivery vehicles for modulating immune responses to improve treatments against cancer and autoimmune diseases, enhancing tissue regeneration capacity, and potentiating vaccination efficacy. Various engineering approaches have been extensively explored to control the NP physical and chemical properties including particle size, shape, surface charge, hydrophobicity, rigidity and surface targeting ligands to modulate immune responses. This review examines a specific set of physical and chemical characteristics of NPs that enable efficient delivery targeted to secondary lymphoid tissues, specifically the lymph nodes and immune cells. A critical analysis of the structure-property-function relationship will facilitate further efforts to engineer new NPs with unique functionalities, identify novel utilities, and improve the clinical translation of NP formulations for immunotherapy.

Immunosenescence and human vaccine immune responses

The age-related dysregulation and decline of the immune system-collectively termed "immunosenescence"-has been generally associated with an increased susceptibility to infectious pathogens and poor vaccine responses in older adults. While numerous studies have reported on the clinical outcomes of infected or vaccinated individuals, our understanding of the mechanisms governing the onset of immunosenescence and its effects on adaptive immunity remains incomplete. Age-dependent differences in T and B lymphocyte populations and functions have been well-defined, yet studies that demonstrate direct associations between immune cell function and clinical outcomes in older individuals are lacking. Despite these knowledge gaps, research has progressed in the development of vaccine and adjuvant formulations tailored for older adults in order to boost protective immunity and overcome immunosenescence. In this review, we will discuss the development of vaccines for older adults in light of our current understanding-or lack thereof-of the aging immune system. We highlight the functional changes that are known to occur in the adaptive immune system with age, followed by a discussion of current, clinically relevant pathogens that disproportionately affect older adults and are the central focus of vaccine research efforts for the aging population. We conclude with an outlook on personalized vaccine development for older adults and areas in need of further study in order to improve our fundamental understanding of adaptive immunosenescence.

Real-Time Imaging of Vaccine Biodistribution Using Zwitterionic NIR Nanoparticles

Efficient and timely delivery of vaccine antigens to the secondary lymphoid tissue is crucial to induce protective immune responses by vaccination. However, determining the longitudinal biodistribution of injected vaccines in the body has been a challenge. Here, the near-infrared (NIR) fluorescence imaging is reported that can efficiently enable the trafficking and biodistribution of vaccines in real time. Zwitterionic NIR fluorophores are conjugated on the surface of model vaccines and tracked the fate of bioconjugated vaccines after intradermal administration. Using an NIR fluorescence imaging system, it is possible to obtain time-course imaging of vaccine trafficking through the lymphatics, observing notable uptake in lymph nodes with minimal nonspecific tissue interactions. Flow cytometry analysis confirmed that the uptake in lymph nodes by antigen presenting cells was highly dependent on the hydrodynamic diameter of vaccines. These results demonstrate that the combination of a real-time NIR fluorescence imaging system and zwitterionic fluorophores is a powerful tool to determine the fate of vaccine antigens. Since such non-specific vaccine uptake causes serious adverse reactions, this method is not only useful for optimization of vaccine design, but also for safety evaluation of clinical vaccine candidates.

Boosting the Immune System, From Science to Myth: Analysis the Infosphere With Google

Background: The concept that one can “boost” immunity is a popular one. Although the only evidence-based approach to this is vaccination, the lay public is exposed to a wide range of information on how to boost immunity. The aim of this study was to analyze such information available on the Internet.

Methods and findings: We visited 185 webpages returned from a Google search on “boost immunity” and classified them by typology (blogs, commercial, government, no-profit, news, professional, scientific journals) and by using standard indicators of health information quality (JAMA score, HONCode). We then analyzed their content in terms of disease and “boosters” mentioned. Commercial and news websites represented one third of the results each. Of the 37 approaches to boost immunity recorded, the top ones were diet (77% of webpages), fruit (69%), vitamins (67%), antioxidants (52%), probiotics (51%), minerals (50%), and vitamin C (49%). Interestingly, vaccines ranked 27th, with only 12% of webpages mentioning them.

Conclusions: Commercial websites are an important component of the information available to the public on the topic, and thus contribute providing biased information.

Vaccine Evolution and Its Application to Fight Modern Threats

Before the development of the first vaccine, infectious diseases were a major cause of death around the globe with life expectancy estimated to be <50 years. Three measures have helped to drastically reduce the burden of infectious diseases but only vaccines have proven to be able to eradicate infectious agents. Herein, we describe new methodologies that have paved the way for what is currently known as modern vaccinology and the use of vaccines to tackle antimicrobial resistance, the biggest global threat of our time.

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.

Subunit-based mucosal vaccine delivery systems for pulmonary delivery - Are they feasible?

Pulmonary infections are the most common cause of death globally. However, the development of mucosal vaccines that provide protective immunity against respiratory pathogens are limited. In contrast to needle-based vaccines, efficient vaccines that are delivered via noninvasive mucosal routes (such as via the lungs and nasal passage) produce both antigen-specific local mucosal IgA and systemic IgG protective antibodies. One major challenge in the development of pulmonary vaccines using subunit antigens however, is the production of optimal immune responses. Subunit vaccines therefore rely upon use of adjuvants to potentiate immune responses. While the lack of suitable mucosal adjuvants has hindered progress in the development of efficient pulmonary vaccines, particle-based systems can provide an alternative approach for the safe and efficient delivery of subunit vaccines. In particular, the rational engineering of particulate vaccines with optimal physicochemical characteristics can produce long-term protective immunity. These protect antigens against enzymatic degradation, target antigen presenting cells and initiate optimal humoral and cellular immunity. This review will discuss our current understanding of pulmonary immunology and developments in fabricating particle characteristics that may evoke potent and durable pulmonary immunity.

Impact of existing vaccines in reducing antibiotic resistance: Primary and secondary effects

Vaccines impact antibiotic-resistant infections in two ways: through a direct reduction in the organisms and strains carrying resistant genes that are specifically targeted by the vaccine and also via a secondary effect through a reduction in febrile illnesses that often lead to the use of antibiotics. We review here the impact of pneumococcal conjugate vaccines (PCVs) on the prevalence of antibiotic-resistant disease and antibiotic usage as an example of the direct effect of vaccines on antibiotic resistance and the impact of influenza vaccination on antibiotic usage as an example of a secondary effect. A prelicensure study of a PCV in Africa demonstrated 67% fewer penicillin-resistant invasive disease episodes in the PCV group compared with controls. Similar studies in the United States and Europe demonstrated reductions in antibiotic use consistent with the vaccines' impact on the risk of otitis media infections in children. Postlicensure reductions in the circulation of antibiotic-resistant strains targeted by the vaccines have been dramatic, with virtual elimination of these strains in children following vaccine introduction. In terms of a secondary effect, following influenza vaccination reductions of 13-50% have been observed in the use of antibiotics by individuals receiving influenza vaccine compared with controls. With the demonstrated effectiveness of vaccination programs in impacting the risk of antibiotic-resistant infections and the increasing threat to public health that these infections represent, more attention needs to be given to development and utilization of vaccines to address antibiotic resistance.

Exploitation of reverse vaccinology and immunoinformatics as promising platform for genome-wide screening of new effective vaccine candidates against Plasmodium falciparum

Background

In the current scenario, designing of world-wide effective malaria vaccine against Plasmodium falciparum remain challenging despite the significant progress has been made in last few decades. Conventional vaccinology (isolate, inactivate and inject) approaches are time consuming, laborious and expensive; therefore, the use of computational vaccinology tools are imperative, which can facilitate the design of new and promising vaccine candidates.

Results

In current investigation, initially 5548 proteins of P. falciparum genome were carefully chosen for the incidence of signal peptide/ anchor using SignalP4.0 tool that resulted into 640 surface linked proteins (SLP). Out of these SLP, only 17 were predicted to contain GPI-anchors using PredGPI tool in which further 5 proteins were considered as malarial antigenic adhesins by MAAP and VaxiJen programs, respectively. In the subsequent step, T cell epitopes of 5 genome derived predicted antigenic adhesins (GDPAA) and 5 randomly selected known malarial adhesins (RSKMA) were analysed employing MHC class I and II tools of IEDB analysis resource. Finally, VaxiJen scored T cell epitopes from each antigen were considered for prediction of population coverage (PPC) analysis in the world-wide population including malaria endemic regions. The validation of the present in silico strategy was carried out by comparing the PPC of combined (MHC class I and II) predicted epitope ensemble among GDPAA (99.97%), RSKMA (99.90%) and experimentally known epitopes (EKE) of P. falciparum (97.72%) pertaining to world-wide human population.

Conclusions

The present study systematically screened 5 potential protective antigens from P. falciparum genome using bioinformatics tools. Interestingly, these GDPAA, RSKMA and EKE of P. falciparum epitope ensembles forecasted to contain highly promiscuous T cell epitopes, which are potentially effective for most of the world-wide human population with malaria endemic regions. Therefore, these epitope ensembles could be considered in near future for novel and significantly effective vaccine candidate against malaria.

Electronic supplementary material

The online version of this article (10.1186/s12859-018-2482-x) contains supplementary material, which is available to authorized users.

β-Glucan as an immune activator and a carrier in the construction of a synthetic MUC1 vaccine

We describe the preparation of a cancer vaccine candidate by conjugating a MUC1 peptide antigen to the β-glucan polysaccharide, which serves both as a carrier and an immune activator. In contrast to amorphous polysaccharides, peptide-β-glucan conjugates form uniform nanoparticles that facilitate the delivery of antigens and binding to myeloid cells, thus leading to the activation of both innate and adaptive immunity.

The Biologics Revolution and Endotoxin Test Concerns

The advent of “at will” production of biologics in lieu of harvesting animal proteins (i.e. insulin) or human cadaver proteins (i.e. growth hormone) has revolutionized the treatment of disease. While the fruits of the biotechnology revolution are widely acknowledged, the realization of the differences in the means of production and changes in the manner of control of potential impurities and contaminants in regard to the new versus the old are less widely appreciated. This chapter is an overview of the biologics revolution in terms of the rigors of manufacturing required to produce them, their mechanism of action, and caveats of endotoxin control. It is a continulation of the previous chapter that established a basic background knowledge of adaptive immune principles necessary to understand the mode of action of both disease causation and biologics therapeutic treatment via immune modulation.

Development of Thermostable Lyophilized Sabin Inactivated Poliovirus Vaccine

Poliomyelitis is a highly contagious disease caused by the poliovirus. While the live attenuated OPV has been the vaccine of choice, a major concern is its ability to revert to a form that can cause paralysis, so-called vaccine-associated paralytic poliomyelitis. Therefore, the new endgame strategy of the Global Polio Eradication Initiative includes the introduction of an IPV. However, the feasibility of the use of current IPV formulations in developing countries is limited, because IPV is insufficiently stable to be purified, transported, and stored under unrefrigerated conditions. We successfully designed the sIPV for use in the dry state that maintains the full vaccine potency in animal models after incubation at ambient temperature. This report provides, for the first time, candidate formulations of sIPV that are stable at elevated temperatures.

As oral poliovirus vaccine (OPV) causes vaccine-associated paralytic poliomyelitis, the polio endgame strategy introduced by the Global Polio Eradication Initiative calls for a phased withdrawal of OPV and an introduction of inactivated poliovirus vaccine (IPV). The introduction of IPV creates challenges in maintaining the cold chain for vaccine storage and distribution. Recent advances in lyophilization have helped in finding a temperature-stable formulation for multiple vaccines; however, poliovirus vaccines have yet to capture a stable, safe formula for lyophilization. In addition, efficient in vitro methods for antigen measurement are needed for screening stable vaccine formulations. Here, we report size exclusion high-performance liquid chromatography (SE-HPLC) as a reliable means to identify the leading lyophilized formulation to generate thermostable Sabin inactivated poliovirus vaccine (sIPV). High-throughput screening and SE-HPLC determined the leading formulation, resulting in 95% D-antigen recovery and low residual moisture content of sIPV following lyophilization. Furthermore, the lyophilized sIPV remained stable after 4 weeks of incubation at ambient temperature and induced strong neutralizing antibodies and full protection of poliovirus receptor transgenic mice against the in vivo challenge of wild-type poliovirus. Overall, this report describes a novel means for the high-throughput evaluation of sIPV antigenicity and a thermostable lyophilized sIPV with in vivo vaccine potency.

M cell targeting engineered biomaterials for effective vaccination

Vaccines are one of the greatest medical interventions of all time and have been successful in controlling and eliminating a myriad of diseases over the past two centuries. Among several vaccination strategies, mucosal vaccines have wide clinical applications and attract considerable interest in research, showing potential as innovative and novel therapeutics. In mucosal vaccination, targeting (microfold) M cells is a frontline prerequisite for inducing effective antigen-specific immunostimulatory effects. In this review, we primarily focus on materials engineered for use as vaccine delivery platforms to target M cells. We also describe potential M cell targeting areas, methods to overcome current challenges and limitations of the field. Furthermore, we present the potential of biomaterials engineering as well as various natural and synthetic delivery technologies to overcome the challenges of M cell targeting, all of which are absent in current literature. Finally, we briefly discuss manufacturing and regulatory processes to bring a robust perspective on the feasibility and potential of this next-generation vaccine technology.

A Bacteriophage T4 Nanoparticle-Based Dual Vaccine against Anthrax and Plague

Following the deadly anthrax attacks of 2001, the Centers for Disease Control and Prevention (CDC) determined that Bacillus anthracis and Yersinia pestis that cause anthrax and plague, respectively, are two Tier 1 select agents that pose the greatest threat to the national security of the United States. Both cause rapid death, in 3 to 6 days, of exposed individuals. We engineered a virus nanoparticle vaccine using bacteriophage T4 by incorporating key antigens of both B. anthracis and Y. pestis into one formulation. Two doses of this vaccine provided complete protection against both inhalational anthrax and pneumonic plague in animal models. This dual anthrax-plague vaccine is a strong candidate for stockpiling against a potential bioterror attack involving either one or both of these biothreat agents. Further, our results establish the T4 nanoparticle as a novel platform to develop multivalent vaccines against pathogens of high public health significance.

Bacillus anthracis and Yersinia pestis, the causative agents of anthrax and plague, respectively, are two of the deadliest pathogenic bacteria that have been used as biological warfare agents. Although Biothrax is a licensed vaccine against anthrax, no Food and Drug Administration-approved vaccine exists for plague. Here, we report the development of a dual anthrax-plague nanoparticle vaccine employing bacteriophage (phage) T4 as a platform. Using an in vitro assembly system, the 120- by 86-nm heads (capsids) of phage T4 were arrayed with anthrax and plague antigens fused to the small outer capsid protein Soc (9 kDa). The antigens included the anthrax protective antigen (PA) (83 kDa) and the mutated (mut) capsular antigen F1 and the low-calcium-response V antigen of the type 3 secretion system from Y. pestis (F1mutV) (56 kDa). These viral nanoparticles elicited robust anthrax- and plague-specific immune responses and provided complete protection against inhalational anthrax and/or pneumonic plague in three animal challenge models, namely, mice, rats, and rabbits. Protection was demonstrated even when the animals were simultaneously challenged with lethal doses of both anthrax lethal toxin and Y. pestis CO92 bacteria. Unlike the traditional subunit vaccines, the phage T4 vaccine uses a highly stable nanoparticle scaffold, provides multivalency, requires no adjuvant, and elicits broad T-helper 1 and 2 immune responses that are essential for complete clearance of bacteria during infection. Therefore, phage T4 is a unique nanoparticle platform to formulate multivalent vaccines against high-risk pathogens for national preparedness against potential bioterror attacks and emerging infections.

New Vaccine Technologies to Combat Outbreak Situations

Ever since the development of the first vaccine more than 200 years ago, vaccinations have greatly decreased the burden of infectious diseases worldwide, famously leading to the eradication of small pox and allowing the restriction of diseases such as polio, tetanus, diphtheria, and measles. A multitude of research efforts focuses on the improvement of established and the discovery of new vaccines such as the HPV (human papilloma virus) vaccine in 2006. However, radical changes in the density, age distribution and traveling habits of the population worldwide as well as the changing climate favor the emergence of old and new pathogens that bear the risk of becoming pandemic threats. In recent years, the rapid spread of severe infections such as HIV, SARS, Ebola, and Zika have highlighted the dire need for global preparedness for pandemics, which necessitates the extremely rapid development and comprehensive distribution of vaccines against potentially previously unknown pathogens. What is more, the emergence of antibiotic resistant bacteria calls for new approaches to prevent infections. Given these changes, established methods for the identification of new vaccine candidates are no longer sufficient to ensure global protection. Hence, new vaccine technologies able to achieve rapid development as well as large scale production are of pivotal importance. This review will discuss viral vector and nucleic acid-based vaccines (DNA and mRNA vaccines) as new approaches that might be able to tackle these challenges to global health.

Routing dependent immune responses after experimental R848-adjuvated vaccination

Most traditional vaccines are administered via the intramuscular route. Other routes of administration however, can induce equal or improved protective memory responses and might provide practical advantages such as needle-free immunization, dose sparing and induction of tissue-specific (mucosal) immunity. Here we explored the differences in immunological outcome after immunization with model antigens via two promising immunization routes (intradermal and intranasal) with or without the experimental adjuvant and TLR7/8-agonist R848. Because the adaptive immune response is largely determined by the local innate cells at the site of immunization, the effect of R848-adjuvation on local cellular recruitment, antigenic uptake by antigen-presenting cells and the initiation of the adaptive response were analyzed for the two routes of administration. We show a general immune-stimulating effect of R848 irrespective of the route of administration. This includes influx of neutrophils, macrophages and dendritic cells to the respective draining lymph nodes and an increase in antigen-positive antigen-presenting cells which leads for both intradermal and intranasal immunization to a mainly T_H1 response. Furthermore, both intranasal and intradermal R848-adjuvated immunization induces a local shift in DC subsets; frequencies of CD11b⁺DC increase whereas CD103⁺DC decrease in relative abundance in the draining lymph node. In spite of these similarities, the outcome of immune responses differs for the respective immunization routes in both magnitude and cytokine profile. Via the intradermal route, the induced T-cell response is higher compared to that after intranasal immunization, which corresponds with the local higher uptake of antigen by antigen-presenting cells after intradermal immunization. Furthermore, R848-adjuvation enhances ex vivo IL-10 and IL-17 production after intranasal, but not intradermal, T-cell activation. Quite the opposite, intradermal immunization leads to a decrease in IL-10 production by the vaccine induced T-cells. This knowledge may lead to a more rational development of novel adjuvanted vaccines administered via non-traditional routes.

Cell culture-derived flu vaccine: Present and future

The benefit of influenza vaccines is difficult to estimate due to the complexity of accurately assessing the burden of influenza. To improve the efficacy of influenza vaccines, vaccine manufacturers have developed quadrivalent influenza vaccine (QIV) formulations for seasonal vaccination by including both influenza B lineages. Three parallel approaches for producing influenza vaccines are attracting the interest of many vaccine manufacturing companies. The first and oldest is the conventional egg-derived influenza vaccine, which is used by the current licensed influenza vaccines. The second approach is a cell culture-derived influenza vaccine, and the third and most recent is synthetic vaccines. Here, we analyze the difficulties with vaccines production in eggs and compare this to cell culture-derived influenza vaccines and discuss the future of cell culture-derived QIVs.

Immunogenicity of diphtheria toxoid and poly(I:C) loaded cationic liposomes after hollow microneedle-mediated intradermal injection in mice

In this study, we aimed to investigate the immunogenicity of cationic liposomes loaded with diphtheria toxoid (DT) and poly(I:C) after hollow microneedle-mediated intradermal vaccination in mice. The following liposomal formulations were studied: DT loaded liposomes, a mixture of free DT and poly(I:C)-loaded liposomes, a mixture of DT-loaded liposomes and free poly(I:C), and liposomal formulations with DT and poly(I:C) either individually or co-encapsulated in the liposomes. Reference groups were DT solution adjuvanted with or without poly(I:C) (DT/poly(I:C)). The liposomal formulations were characterized in terms of particle size, zeta potential, loading and release of DT and poly(I:C). After intradermal injection of BALB/c mice with the formulations through a hollow microneedle, the immunogenicity was assessed by DT-specific ELISAs. All formulations induced similar total IgG and IgG1 titers. However, all the liposomal groups containing both DT and poly(I:C) showed enhanced IgG2a titers compared to DT/poly(I:C) solution, indicating that the immune response was skewed towards a Th1 direction. This enhancement was similar for all liposomal groups that contain both DT and poly(I:C) in the formulations. Our results reveal that a mixture of DT encapsulated liposomes and poly(I:C) encapsulated liposomes have a similar effect on the antibody responses as DT and poly(I:C) co-encapsulated liposomes. These findings may have implications for future design of liposomal vaccine delivery systems.

Progress in biopharmaceutical development

Since its introduction in 1982, biopharmaceutical drugs have revolutionized the treatment of a broad spectrum of diseases and are increasingly used in nearly all branches of medicine. In recent years, the biopharmaceuticals market has developed much faster than the market for all drugs and is believed to have great potential for further dynamic growth because of the tremendous demand for these drugs. Biobetters, which contain altered active pharmaceutical ingredients with enhanced efficacy, will play an important role in the development of biopharmaceuticals. Another significant group of biopharmaceuticals are biosimilars. Their introduction in the European Union and, recently, the Unites States markets will reduce the costs of biopharmaceutical treatment. This review highlights recent progress in the field of biopharmaceutical development and issues concerning the registration of innovative biopharmaceuticals and biosimilars. The leading class of biopharmaceuticals, the current biopharmaceuticals market, and forecasts are also discussed.

Challenges in adult vaccination

Life-long primary prevention interventions beginning and continuing throughout an individual's lifetime are increasingly seen as key to meeting the global healthcare challenges that accompany demographic changes - a concept referred to as "Healthy aging". In this perspective, vaccination is seen as part of a triad, together with healthy diet and exercise. Current adult vaccine coverage is lower than target vaccination rates in most developed countries, and so vaccine preventable diseases continue to present a substantial burden on health and healthcare resources, especially in older individuals. In part, this is due to lack of knowledge and understanding of the benefits of vaccination, inconsistent recommendations by providers and uncertainties about cost benefits. However, lower vaccine effectiveness in older adults plays a part, and new vaccines with novel characteristics to improve effectiveness in older adults are required. A life-course immunization approach to ensure optimal vaccine uptake across adults of all ages can be expected to reduce morbidity and mortality in later life. To achieve this, greater emphasis on public and healthcare provider education is necessary, based on appropriate economic analyses that demonstrate the overall value of vaccination. This article introduces the technical, economic, political and demographic issues that make establishing effective adult vaccination programs such a difficult, but pressing issue, and outlines some of the steps that are now being taken to address them. Key messages Life-long preventive activities that start and continue throughout life are essential, especially as the world's population is "getting older". This "Healthy aging" approach includes not only healthy diet and physical exercise; vaccination is critical in reducing some infectious diseases and their complications. Many adults, especially older adults (who have lower immunity than younger people) develop infections such as influenza and shingles that could potentially be prevented through vaccination. This review provides a perspective on the challenges in delivering a life-course immunization program. While some vaccines are less effective in older people, newer vaccines have been developed which provide stronger and longer protection in older patients than standard existing vaccines. However, the benefits of vaccination can only be realized if the vaccines are recommended and used. For that purpose, greater education of patients and their healthcare providers is necessary. Better knowledge of vaccines and making sure that all adults are up to date with all their recommended vaccines is an essential part of "Healthy aging". This should prevent not only vaccine-preventable diseases but also reduce the risk of complications in later life.

Alum/Toll-Like Receptor 7 Adjuvant Enhances the Expansion of Memory B Cell Compartment Within the Draining Lymph Node

Vaccination is one of the most cost-effective health interventions and, with the exception of water sanitization, no other action has had such a major effect in mortality reduction. Combined with other approaches, such as clean water, better hygiene, and health education, vaccination contributed to prevent millions of cases of deaths among children under 5 years of age. New or improved vaccines are needed to fight some vaccine-preventable diseases that are still a threat for the public health globally, as reported also in the Global Vaccine Action Plan (GVAP) endorsed by the World Health Assembly in 2012. Adjuvants are substances that enhance the effectiveness of vaccination, but despite their critical role for the development of novel vaccines, very few of them are approved for use in humans. Aluminum hydroxide (Alum) is the most common adjuvant used in vaccines administered in millions of doses around the world to prevent several dangerous diseases. The development of an improved version of Alum can help to design and produce new or better vaccines. Alum/toll-like receptor (TLR)7 is a novel Alum-based adjuvant, currently in phase I clinical development, formed by the attachment of a benzonaphthyridine compound, TLR7 agonist, to Alum. In preclinical studies, Alum/TLR7 showed a superior adjuvant capacity, compared to Alum, in several disease models, such as meningococcal meningitis, anthrax, staphylococcus infections. None of these studies reported the effect of Alum/TLR7 on the generation of the B cell memory compartment, despite this is a critical aspect to achieve a better immunization. In this study, we show, for the first time, that, compared to Alum, Alum/TLR7 enhances the expansion of the memory B cell compartment within the draining lymph node (LN) as result of intranodal sustained proliferation of antigen-engaged B cells and/or accumulation of memory B cells. In addition, we observed that Alum/TLR7 induces a recruitment of naïve antigen-specific B cells within the draining LN that may help to sustain the germinal center reaction. Our data further support Alum/TLR7 as a new promising adjuvant, which might contribute to meet the expectations of the GVAP for 2020 and beyond.

Blocking interleukin-4 enhances efficacy of vaccines for treatment of opioid abuse and prevention of opioid overdose

Vaccines offer an option to treat heroin and prescription opioid abuse and prevent fatal overdoses. Opioid vaccines elicit antibodies that block opioid distribution to the brain and reduce opioid-induced behavioral effects and toxicity. The major limitation to the translation of addiction vaccines is that efficacy is observed only in subjects achieving optimal drug-specific serum antibody levels. This study tested whether efficacy of a vaccine against oxycodone is increased by immunomodulators targeting key cytokine signaling pathways involved in B and T cell lymphocyte activation. Blockage of IL-4 signaling increased vaccine efficacy in blocking oxycodone distribution to the brain and protection against opioid-induced behavior and toxicity in mice. This strategy generalized to a peptide-protein conjugate immunogen, and a tetanus-diphtheria-pertussis vaccine. These data demonstrate that cytokine-based immunomodulators increase efficacy of vaccines against small molecules, peptides and proteins, and identify IL-4 as a pharmacological target for improving efficacy of next-generation vaccines.

Understanding modern-day vaccines: what you need to know

Vaccines are considered to be one of the greatest public health achievements of the last century. Depending on the biology of the infection, the disease to be prevented, and the targeted population, a vaccine may require the induction of different adaptive immune mechanisms to be effective. Understanding the basic concepts of different vaccines is therefore crucial to understand their mode of action, benefits, risks, and their potential real-life impact on protection. This review aims to provide healthcare professionals with background information about the main vaccine designs and concepts of protection in a simplified way to improve their knowledge and understanding, and increase their confidence in the science of vaccination ( Supplementary Material ). KEY MESSAGE Different vaccine designs, each with different advantages and limitations, can be applied for protection against a particular disease. Vaccines may contain live-attenuated pathogens, inactivated pathogens, or only parts of pathogens and may also contain adjuvants to stimulate the immune responses. This review explains the mode of action, benefits, risks and real-life impact of vaccines by highlighting key vaccine concepts. An improved knowledge and understanding of the main vaccine designs and concepts of protection will help support the appropriate use and expectations of vaccines, increase confidence in the science of vaccination, and help reduce vaccine hesitancy.

Chimeras could help in the fight against leptospirosis

Understanding the structure of an antigen can guide the design of improved antigen-based vaccines.

A smart multi-functional coating based on anti-pathogen micelles tethered with copper nanoparticlesviaa biosynthesis method usingl-vitamin C

A multi-functional anti-pathogen coating with “release-killing”, “contact-killing” and “anti-adhesion” properties was prepared from biocompatible polymer encapsulated chlorine dioxide (ClO₂) which protected the active ingredient from the outside environment.

Proteome-scale identification of Leishmania infantum for novel vaccine candidates: A hierarchical subtractive approach

Vaccines are one of the most significant achievements in medical science. However, vaccine design is still challenging at all stages. The selection of antigenic peptides as vaccine candidates is the first and most important step for vaccine design. Experimental selection of antigenic peptides for the design of vaccines is a time-consuming, labor-intensive and expensive procedure. More recently, in the light of computer-aided biotechnology and reverse vaccinology, the precise selection of antigenic peptides and rational vaccine design against many pathogens have developed. In this study, the whole proteome of Leishmania infantum was analyzed using a pipeline of algorithms. From the set of 8045 proteins of L. infantum, sixteen novel antigenic proteins were derived using a hierarchical proteome subtractive analysis. These novel vaccine targets can be utilized as top candidates for designing the new prophylactic or therapeutic vaccines against visceral leishmaniasis. Significantly, all the sixteen novel vaccine candidates are non-allergen antigenic proteins that have not been used for the design of vaccines against visceral leishmaniasis until now.

Fighting against a protean enemy: immunosenescence, vaccines, and healthy aging

The progressive increase of the aged population worldwide mandates new strategies to ensure sustained health and well-being with age. The development of better and/or new vaccines against pathogens that affect older adults is one pivotal intervention in approaching this goal. However, the functional decline of various physiological systems, including the immune system, requires novel approaches to counteract immunosenescence. Although important progress has been made in understanding the mechanisms underlying the age-related decline of the immune response to infections and vaccinations, knowledge gaps remain, both in the areas of basic and translational research. In particular, it will be important to better understand how environmental factors, such as diet, physical activity, co-morbidities, and pharmacological treatments, delay or contribute to the decline of the capability of the aging immune system to appropriately respond to infectious diseases and vaccination. Recent findings suggest that successful approaches specifically targeted to the older population can be developed, such as the high-dose and adjuvanted vaccines against seasonal influenza, the adjuvanted subunit vaccine against herpes zoster, as well as experimental interventions with immune-potentiators or immunostimulants. Learning from these first successes may pave the way to developing novel and improved vaccines for the older adults and immunocompromised. With an integrated, holistic vaccination strategy, society will offer the opportunity for an improved quality of life to the segment of the population that is going to increase most significantly in numbers and proportion over future decades.

Multicriteria decision analysis and core values for enhancing vaccine-related decision-making

Vaccines have the potential to transform the health of all individuals and to reduce the health inequality between rich and poor countries. However, to achieve these goals, it is no longer sufficient to prioritize vaccine development using cost-effectiveness as the sole indicator. During a symposium entitled "Mission Grand Convergence-The Role of Vaccines," held in Siena, Italy, in July 2015, key stakeholders agreed that the prioritization of vaccine development and deployment must use multicriteria decision-making based on the following core concepts: (i) mortality and severity of the disease, (ii) vaccine safety considerations, and (iii) economic evaluation that captures the full benefits of vaccination.

Innovative Approaches to Improve Anti-Infective Vaccine Efficacy

Safe and efficacious vaccines are arguably the most successful medical interventions of all time. Yet the ongoing discovery of new pathogens, along with emergence of antibiotic-resistant pathogens and a burgeoning population at risk of such infections, imposes unprecedented public health challenges. To meet these challenges, innovative strategies to discover and develop new or improved anti-infective vaccines are necessary. These approaches must intersect the most meaningful insights into protective immunity and advanced technologies with capabilities to deliver immunogens for optimal immune protection. This goal is considered through several recent advances in host-pathogen relationships, conceptual strides in vaccinology, and emerging technologies. Given a clear and growing risk of pandemic disease should the threat of infection go unmet, developing vaccines that optimize protective immunity against high-priority and antibiotic-resistant pathogens represents an urgent and unifying imperative.

Identification of New Features from Known Bacterial Protective Vaccine Antigens Enhances Rational Vaccine Design

With many protective vaccine antigens reported in the literature and verified experimentally, how to use the knowledge mined from these antigens to support rational vaccine design and study underlying design mechanism remains unclear. In order to address the problem, a systematic bioinformatics analysis was performed on 291 Gram-positive and Gram-negative bacterial protective antigens with experimental evidence manually curated in the Protegen database. The bioinformatics analyses evaluated included subcellular localization, adhesin probability, peptide signaling, transmembrane α-helix and β-barrel, conserved domain, Clusters of Orthologous Groups, and Gene Ontology functional annotations. Here we showed the critical role of adhesins, along with subcellular localization, peptide signaling, in predicting secreted extracellular or surface-exposed protective antigens, with mechanistic explanations supported by functional analysis. We also found a significant negative correlation of transmembrane α-helix to antigen protectiveness in Gram-positive and Gram-negative pathogens, while a positive correlation of transmembrane β-barrel was observed in Gram-negative pathogens. The commonly less-focused cytoplasmic and cytoplasmic membrane proteins could be potentially predicted with the help of other selection criteria such as adhesin probability and functional analysis. The significant findings in this study can support rational vaccine design and enhance our understanding of vaccine design mechanisms.

Lipopolysaccharide Detection across the Kingdoms of Life

Studies in recent years have uncovered a diverse set of eukaryotic receptors that recognize lipopolysaccharide (LPS), the major outer-membrane component of Gram-negative bacteria. Indeed, Toll-like receptors, G-protein-coupled receptors, integrins, receptor-like kinases, and caspases have emerged as important LPS-interacting proteins. In this review, the mammalian receptors that detect LPS are described. I highlight how no host protein is involved in all LPS responses, but a single lipid (phosphatidylinositol-4,5-bisphosphate) regulates many LPS responses, including endocytosis, phagocytosis, inflammation, and pyroptosis. I further describe LPS response systems that operate specifically in plants, and discuss potentially new LPS response systems that await discovery. This diversity of receptors for a single microbial product underscores the importance of host-microbe interactions in multiple kingdoms of life.

Immunological tolerance as a barrier to protective HIV humoral immunity

HIV-1 infection typically eludes antibody control by our immune system and is not yet prevented by a vaccine. While many viral features contribute to this immune evasion, broadly neutralizing antibodies (bnAbs) against HIV-1 are often autoreactive and it has been suggested that immunological tolerance may restrict a neutralizing antibody response. Indeed, recent Ig knockin mouse studies have shown that bnAb-expressing B cells are largely censored by central tolerance in the bone marrow. However, the contribution of peripheral tolerance in limiting the HIV antibody response by anergic and potentially protective B cells is poorly understood. Studies using mouse models to elucidate how anergic B cells are regulated and can be recruited into HIV-specific neutralizing antibody responses may provide insight into the development of a protective HIV-1 vaccine.

Age-appropriate versus up-to-date coverage of routine childhood vaccinations among young children in Israel

BACKGROUND AND AIMS

Routine childhood vaccinations schedules recommend that children receive the vaccine doses at specific ages. Vaccination coverage data are conventionally reported by the up-to-date method. We aimed to assess vaccination timeliness by the age-appropriate method and compare with the up-to-date vaccination coverage.

METHODS

Assessment of age-appropriate and up-to-date vaccination coverage among children born in Israel in 2009 and followed to age 48 months (national representative sample, n = 3892). The vaccinations included: Hepatitis B vaccine (HBV), Diphtheria-Tetanus-acellular Pertussis-Polio-Haemophilus-influenzae-b (DTaP-IPV-Hib), Pneumococcal conjugate vaccine (PCV), Measles-mumps-rubella-varicella vaccine (MMR/MMRV) and Hepatitis A vaccine (HAV). The categories defined: age-appropriate (at the recommended age and up to 1 month), delayed less than 6 months, delayed 6 months and above and unvaccinated (48 months).

RESULTS

The age-specific vaccinations assessment showed considerable delay in receipt of routine vaccination. While most (96%, 95%, 91%, 96%, 94% and 86%) children were vaccinated up-to-date for HBV3, DTaP-IPV-Hib4, PCV3, MMR/MMRV1, HAV1and HAV2 vaccine doses; only 26%, 29%, 47%, 64%, 55% and 12% were vaccinated age-appropriate. Vaccination delay was more common in vaccines with multiple doses. Vaccination delay was associated with high child's birth order, low socio-economic rank, ethnicity (delay more common in Jews vs. Arabs), season of birth (winter) and delayed receipt of DTaP-IPV-Hib vaccine 1st dose.

CONCLUSIONS

This study assessed age-appropriate childhood vaccination coverage in a national cohort of children. While the overall vaccination coverage stands in line with the WHO goals, vaccination timeliness and equity are inadequate and targeted public health intervention programs aimed at vaccination timeliness are necessary.

Reverse Vaccinology: An Approach for Identifying Leptospiral Vaccine Candidates

Leptospirosis is a major public health problem with an incidence of over one million human cases each year. It is a globally distributed, zoonotic disease and is associated with significant economic losses in farm animals. Leptospirosis is caused by pathogenic Leptospira spp. that can infect a wide range of domestic and wild animals. Given the inability to control the cycle of transmission among animals and humans, there is an urgent demand for a new vaccine. Inactivated whole-cell vaccines (bacterins) are routinely used in livestock and domestic animals, however, protection is serovar-restricted and short-term only. To overcome these limitations, efforts have focused on the development of recombinant vaccines, with partial success. Reverse vaccinology (RV) has been successfully applied to many infectious diseases. A growing number of leptospiral genome sequences are now available in public databases, providing an opportunity to search for prospective vaccine antigens using RV. Several promising leptospiral antigens were identified using this approach, although only a few have been characterized and evaluated in animal models. In this review, we summarize the use of RV for leptospirosis and discuss the need for potential improvements for the successful development of a new vaccine towards reducing the burden of human and animal leptospirosis.

Séance bi-académique de l’Académie nationale de médecine et de l’Académie des Sciences: « Confiance et défiance vis-à-vis des vaccins »

SUMMARYThe explosion of vaccines during the 20th century allowed the control of numerous infectious plagues but multiple challenges oppose conservation and extension of these successes. The hesitation of modern societies in front of vaccinations requires researches in life, human and social sciences in order to reach a better understanding of vaccines mechanism of action and to improve the tolerance and acceptability of vaccines and additives. The ageing of the populations and the increase of subjects at risk also require to improve the immunogenicity and the efficiency of existing vaccines. The constant emergence of new epidemics or the development of the antibio-resistance imposes innovation and development of new vaccines. The recent difficulties faced by the development of vaccines against malaria, tuberculosis or AIDS illustrate the necessity of moving beyond classical recipes and of elaborating new vectors and new adjuvants, of better understanding the heterogeneity of vaccine immunity and of developing alternative routes of immunization. Multidisciplinary researches using the most recent advances in molecular, structural and cellular biology, in microbiology, immunology and of genetic engineering to answer these worldwide challenges.

Antiviral Probiotics: A New Concept in Medical Sciences

In recent decades, probiotics have shown beneficial effects on animal and human health. Probiotics can protect the host against several health threats, including infectious diseases. Before 1995, researchers believed that the effect of probiotics was only on gut microbiota which can restore the gut flora and thus prevent pathogenic bacteria from triggering gastroenteritis. Recent studies have shown that the immunomodulatory activity is the most important mechanism of action of probiotics. From this information, researchers started to evaluate the effect of some immunobiotics, not only on pathogenic bacteria but also on viruses, including enteric and respiratory viruses. Several studies have confirmed the potential antiviral activity of some probiotics due to the immunomodulatory effect. These studies were conducted on humans (clinical trials) and in animal models. In this chapter, probiotics with antiviral effect against respiratory and enteric viruses will be presented and discussed, as well as their mechanisms of action.