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Reliable experimental data and models are required to better understand and design chemical looping processes with oxygen carrier materials like ilmenite. A dubious variability of suggested kinetics for similar oxygen carrier materials has been presented in the literature. Part I of this work focuses on thermogravimetric analysis (TGA) of gas–solid kinetics and addresses several of its challenges, which are possible reasons behind such deviations. The reduction of synthetic ilmenite (60 mass% Fe 2 O 3 ＋ 40 mass% TiO 2) powder with H 2 in a TGA system was investigated for this purpose. Multiple steps were necessary to overcome mass transfer limitations during the measurements: (i) small sample masses down to 1.6 mg, (ii) high gas flow rates, (iii) a suitable sample carrier and (iv) proper sample dispersion on the sample carrier. Three types of sample carriers (crucible, basket and plate) were tested; the plate showed the best performance overall. It was alarming that an exemplary increase in sample mass from 1.6 to 3 mg, which was still significantly lower than all other studies reviewed, already introduced a noticeable influence of diffusion. Isothermal (650–950 ° C , 17–50 vol% H 2) and nonisothermal parameter studies were conducted and yielded vastly different isoconversional activation energies. A computational fluid dynamics (CFD) study of the TGA system suggested considerable axial dispersion of H 2 influencing the initial conversion period. These findings help to assess the reliability of kinetic studies and guide towards diffusion-free, kinetic measurements. The results will be used for model development in part II. • The reduction of synthetic ilmenite with hydrogen was analyzed in a TGA. • Temperature and concentration influences were studied in the kinetic regime. • The questionable variability of results in similar kinetic studies was addressed. • Small increase in mass (1.6 mg to 3 mg) already changed apparent activation energy. • Sample carrier/dispersion, gas flow field and temperature ramps were studied. [ABSTRACT FROM AUTHOR]

Strengthening governance is an essential strategy to tackling antimicrobial resistance (AMR) at all levels: global, national, regional, and local. To date, no systematic approach to governance of national action plans on AMR exists. To address this issue, we aimed to develop the first governance framework to offer guidance for both the development and assessment of national action plans on AMR. We reviewed health system governance framework reviews to inform the basic structure of our framework, international guidance documents from WHO, the Food and Agriculture Organization, the World Organisation for Animal Health, and the European Commission, and sought the input of 25 experts from international organisations, government ministries, policy institutes, and academic institutions to develop and refine our framework. The framework consists of 18 domains with 52 indicators that are contained within three governance areas: policy design, implementation tools, and monitoring and evaluation. To consider the dynamic nature of AMR, the framework is conceptualised as a cyclical process, which is responsive to the context and allows for continuous improvement and adaptation of national action plans on AMR. [ABSTRACT FROM AUTHOR]

The so-called "layer model" or "interface-based model" is a simplified single particle model, originally developed for shorter computation time during computational fluid dynamics (CFD) simulations. A reactive biomass particle is assumed to consist of successive layers, in which drying, pyrolysis and char conversion occur sequentially. The interfaces between these layers are the reaction fronts. The model has already been validated for drying, pyrolysis and char oxidation. Layer models in the literature have commonly employed surface reactions at the reaction front to describe char conversion. In this work, the suitability of this surface reaction concept is assessed when gasifying biochar. It is shown that a particular layer model, already available, which originally employed surface reactions, was unable to adequately describe the mass loss during gasification of a biochar. In order to overcome this incapability, the model was extended to consider volumetric reactions in the char layer. The influence of intraparticle diffusion was considered through an effectiveness factor. The model is easily adaptable for different gas-solid kinetic rate laws, while still allowing for comparably fast solutions of the model equations. The extended model was validated using theoretical calculations and experimental measurements from literature. It was demonstrated that intraparticle diffusion can significantly slow down the biochar gasification process. A general guideline for when to employ volumetric reactions, rather than surface reactions, and when to consider intraparticle diffusion is provided based on the Thiele modulus as the criterion. [ABSTRACT FROM AUTHOR]

Despite the broad knowledge about the pathogenicity of Streptococcus pyogenes there is still a controversy about the correlate of protection in GAS infections. We aimed in further improving the immune responses stimulated against GAS comparing different vaccine formulations including bis-(3′,5′)-cyclic dimeric adenosine monophosphate (c-di-AMP) and BPPCysMPEG, a derivative of the macrophage-activating lipopeptide (MALP-2), as adjuvants, respectively, to be administered with and without the universal T helper cell epitope P25 along with the optimized B cell epitope J14 of the M protein and B and T cell epitopes of SfbI. Lipopeptide based nano carrier systems (LCP) were used for efficient antigen delivery across the mucosal barrier. The stimulated immune responses were efficient in protecting mice against a respiratory challenge with a lethal dose of a heterologous S. pyogenes strain. Moreover, combination of the LCP based peptide vaccine with c-di-AMP allowed reduction of antigen dose at the same time maintaining vaccine efficacy. [ABSTRACT FROM AUTHOR]

The most promising strategy to sustainably prevent infectious diseases is vaccination. However, emerging as well as re-emerging diseases still constitute a considerable threat. Furthermore, lack of compliance and logistic constrains often result in the failure of vaccination campaigns. To overcome these hurdles, novel vaccination strategies need to be developed, which fulfill maximal safety requirements, show maximal efficiency and are easy to administer. Mucosal vaccines constitute promising non-invasive approaches able to match these demands. Here we demonstrate that nanoparticle (polyphosphazenes)-based vaccine formulations including c-di-AMP as adjuvant, cationic innate defense regulator peptides (IDR) and ovalbumin (OVA) as model antigen were able to stimulate strong humoral and cellular immune responses, which conferred protection against the OVA expressing influenza strain A/WSN/OVA I (H1N1). The presented results confirm the potency of nanoparticle-based vaccine formulations to deliver antigens across the mucosal barrier, but also demonstrate the necessity to include adjuvants to stimulate efficient antigen-specific immune responses. [ABSTRACT FROM AUTHOR]

Herein, we provide the first description of a synthetic delivery method for self-replicating replicon RNAs (RepRNA) derived from classical swine fever virus (CSFV) using a Coatsome-replicon vehicle based on Coatsome® SS technologies. This results in an unprecedented efficacy when compared to well-established polyplexes, with up to ∼65 fold-increase of the synthesis of RepRNA-encoded gene of interest (GOI). We demonstrated the efficacy of such Coatsome-replicon vehicles for RepRNA-mediated induction of CD8 T-cell responses in mice. Moreover, we provide new insights on physical properties of the RepRNA, showing that the removal of all CSFV structural protein genes has a positive effect on the translation of the GOI. Finally, we successfully engineered RepRNA constructs encoding a porcine reproductive and respiratory syndrome virus (PRRSV) antigen, providing an example of antigen expression with potential application to combat viral diseases. The versatility and simplicity of modifying and manufacturing these Coatsome-replicon vehicle formulations represents a major asset to tackle foreseeable emerging pandemics. This work is the first description of a synthetic delivery method combining self-replicating RNA (RepRNA) and Coatsome® SS technologies. Unprecedented efficacy was seen in vitro when compared to well-established polyplexes. In mice, a single immunization led to the induction of a specific CD8+ T-cell response. Finally, the removal of all RepRNA structural protein genes further increases the translation rate of the foreign antigen. Overall, this vaccine approach is a major improvement in the field of synthetic RNA vaccines and has the potential to be a major asset to tackle foreseeable emerging pandemics. [Display omitted] [ABSTRACT FROM AUTHOR]

Self-amplifying replicon RNA (RepRNA) are large molecules (12-14 kb); their self-replication amplifies mRNA template numbers, affording several rounds of antigen production, effectively increasing vaccine antigen payloads. Their sensitivity to RNase-sensitivity and inefficient uptake by dendritic cells (DCs) – absolute requirements for vaccine design – were tackled by condensing RepRNA into synthetic, nanoparticulate, polyethylenimine (PEI)-polyplex delivery vehicles. Polyplex-delivery formulations for small RNA molecules cannot be transferred to RepRNA due to its greater size and complexity; the N:P charge ratio and impact of RepRNA folding would influence polyplex condensation, post-delivery decompaction and the cytosolic release essential for RepRNA translation. Polyplex-formulations proved successful for delivery of RepRNA encoding influenza virus hemagglutinin and nucleocapsid to DCs. Cytosolic translocation was facilitated, leading to RepRNA translation. This efficacy was confirmed in vivo , inducing both humoral and cellular immune responses. Accordingly, this paper describes the first PEI-polyplexes providing efficient delivery of the complex and large, self-amplifying RepRNA vaccines. From the Clinical Editor The use of self-amplifying replicon RNA (RepRNA) to increase vaccine antigen payloads can potentially be useful in effective vaccine design. Nonetheless, its use is limited by the degradation during the uptake process. Here, the authors attempted to solve this problem by packaging RepRNA using polyethylenimine (PEI)-polyplex delivery vehicles. The efficacy was confirmed in vivo by the appropriate humoral and cellular immune responses. This novel delivery method may prove to be very useful for future vaccine design. [ABSTRACT FROM AUTHOR]

High-temperature corrosion in biomass fired boilers is still an insufficiently explored phenomenon which causes unscheduled plant shutdowns and hence, economical problems. To investigate the high-temperature corrosion and deposit formation behaviour of superheater tube bundles, online corrosion probe as well as deposit probe measurements have been carried out in a specially designed fixed bed/drop tube reactor in order to simulate a superheater boiler tube under well-controlled conditions. The investigated boiler steel 13CrMo4–5 is commonly used as steel for superheater tube bundles in biomass fired boilers. Forest wood chips and quality sorted waste wood (A1–A2 according to German standards) as relevant fuels have been selected to investigate the influence on the deposit formation and corrosion behaviour. The following influencing parameter variations have been performed during the test campaigns: flue gas temperature between 650 and 880 ° C , steel temperature between 450 and 550 ° C and flue gas velocity between 2 and 8 m/s. One focus of the work presented is the detailed investigation of the structure and the chemical composition of the deposits formed as well as of the corrosion products. A further goal of the work presented was the development of an empirical model which can be used within CFD simulations of flow and heat transfer to calculate and evaluate the local corrosion potential of biomass fired plants already at the planning stage. The corrosion probe measurements show a clear dependency on the parameters investigated and the empirical function developed reproduces the measured corrosion behaviour sufficiently accurate. Since the additional calculation time within the CFD simulation is negligible the model represents a helpful tool for plant designers to estimate whether high-temperature corrosion is of relevance for a certain plant or not, when using fuels with similar compositions and the steel 13CrMo4–5. [ABSTRACT FROM AUTHOR]

Trans-follicular (TF) vaccination has recently been studied as a unique route for non-invasive transcutaneous vaccination. The present study aims to extensively characterize the immune responses triggered by TF vaccination using ovalbumin loaded chitosan-PLGA (poly lactic-co-glycolic acid) nanoparticles without skin pre-treatment to preserve skin integrity. The impact of formulation composition i.e. antigenic solution or antigen-loaded nanoparticles with or without adjuvant [bis-(3′,5′)-cyclic dimeric adenosine monophosphate] on immune response quality following TF immunization was analyzed and compared with immune responses obtained after tape stripping the skin. The results presented in this study confirm the ability of nanoparticle based vaccine formulations to deliver antigen across the intact skin via the follicular route, but at the same time demonstrate the necessity to include adjuvants to generate efficient antigen-specific humoral and cellular immune responses. From the Clinical Editor This study confirms the ability of nanoparticle based vaccine formulations to deliver antigen across the intact skin via the follicular route, and highlights the necessity to include adjuvants to generate efficient immune responses. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the work on the development and test of a basic design tool for the automatic performance of parameter studies for the optimisation of biomass combustion plants is presented. The model consists of parameterisation and optimisation routines linked with an in-house developed empirical packed bed combustion model as well as gas phase CFD models especially adapted for biomass grate furnaces. To test and verify the routine developed, it has been applied to the optimisation of a 180 kWth pilot-scale grate furnace. The main focus was on the minimisation of CO emissions and the pressure loss by changing the diameter and angle of the secondary air nozzles. The simulation results show that the time of the optimisation process can be reduced considerably by the automatic routine developed and the evaluation of several independent design parameters is possible. This new procedure forms an important milestone towards automatic CFD-based furnace and boiler optimisations in the future. [Copyright &y& Elsevier]

Abstract: Severe acute respiratory syndrome (SARS) is a serious infectious disease caused by the SARS coronavirus. We assessed the potential of prime-boost vaccination protocols based on the nucleocapsid (NC) protein co-administered with a derivative of the mucosal adjuvant MALP-2 or expressed by modified Vaccinia virus Ankara (MVA–NC) to stimulate humoral and cellular immune responses at systemic and mucosal levels. The obtained results demonstrated that strong immune responses can be elicited both at systemic and mucosal levels following a heterologous prime-boost vaccination protocol consisting in priming with NC protein add-mixed with MALP-2 by intranasal route and boosting with MVA–NC by intramuscular route. [Copyright &y& Elsevier]

Abstract: Adjuvants are usually required to stimulate efficient immune responses after vaccination by the mucosal route. Unfortunately, only a few molecules have been described, which exhibit this property. Thus, there is an urgent need to develop new mucosal adjuvants. Our results demonstrate that the fibrinogen–albumin–IgG receptor (FAI) from group C streptococci is a promising mucosal adjuvant. Strong antigen-specific antibody responses were stimulated at both systemic and mucosal levels when model antigens were co-administered with FAI. Immunizations performed using truncated derivatives demonstrated that the fragment encompassing the IgG- and fibrinogen-binding regions represents the minimal domain possessing adjuvant activity. FAI specifically targets B cells, thereby supporting their activation and antibody production, even in the absence of T cell help. Co-administration of antigens with FAI also resulted in elicitation of strong antibody responses in CBA/N Xid mice, which exhibit a deficiency in humoral immunity. The overcoming of their unresponsiveness by co-administration of FAI suggests that this promising adjuvant can be exploited for the establishment of vaccination strategies in patients affected by immune deficiencies of the B cell compartment. [Copyright &y& Elsevier]

Abstract: The identification of new adjuvants is a critical need in vaccinology. In this work, it is demonstrated that bis-(3′,5′)-cyclic dimeric guanosine monophosphate (cdiGMP) exhibits potent adjuvant properties. Subcutaneous co-administration of cdiGMP with β-galactosidase (β-Gal) to mice resulted in the elicitation of significantly higher antigen-specific serum IgG titres than in animals receiving β-Gal alone. Strong cellular immune responses, which were characterized by a balanced Th1/Th2 pattern, were also observed in response to the β-Gal protein and a peptide encompassing its MHC class I-restricted epitope in immunized animals. These results suggest that cdiGMP represents a promising adjuvant for vaccine development. [Copyright &y& Elsevier]

Abstract: We investigated whether intranasal immunisation with diphtheria toxoid (DT) conjugated polypeptides encompassing T and B cell epitopes of the SfbI protein (FNBR) or a conformational-constrained B cell epitope of the M1 protein (J8) was able to confer protection against lethal mucosal challenge with a heterologous Streptococcus pyogenes strain. To this end, BALB/c mice were immunised with the conjugates. Strong antigen-specific antibody responses were observed in both serum and mucosal secretions. Vaccinated mice were challenged 10 days after the last boost by the intranasal route. Animals receiving FNBR-DT co-administered with either the cholera toxin B subunit (CTB) or the TLR 2/6 agonist MALP-2 were efficiently protected against the virulent S. pyogenes strain (90% and 70% survival, respectively), whereas those immunised with J8-DT plus either CTB or MALP-2 showed intermediate levels of protection (60% and 40%, respectively). The obtained results indicate that in our experimental animal model peptide-based conjugate vaccines represent a valid alternative to protect against streptococcal infection. [Copyright &y& Elsevier]

Abstract: Streptococcus pyogenes is a human pathogen causing invasive and non-invasive diseases, as well as severe sequels, such as rheumatic fever. Several bacterial factors have been proposed as candidate vaccine antigens. Among them, the serum opacity factor (SOF), which was able to confer protective immunity against an intraperitoneal challenge after vaccination by the parenteral route. In an attempt to develop more efficient vaccines, we combined SOF with an additional well-known protective antigen, namely, the fibronectin-binding protein I (SfbI). Intranasal immunization of mice with SOF and SfbI stimulates strong systemic and mucosal immune responses against both antigens. Animals vaccinated with SfbI, alone or in combination with SOF, were also efficiently protected against a lethal challenge with a SOF/SfbI-positive virulent S. pyogenes strain (80% survival). In contrast, those vaccinated with SOF alone were not protected against a mucosal challenge (100% lethality), which mimics more closely natural infections. These results highlight the importance of developing adequate experimental animal models to evaluate vaccine efficiency, according to the selected antigen. [Copyright &y& Elsevier]

Abstract: We have demonstrated that the fibrinogen–albumin–IgG receptor of group C streptococci (FAI) targets B-cells in vivo. We exploited the targeting properties of FAI to improve the immune responses stimulated by soluble antigens administered by the mucosal route. Enhanced systemic and mucosal immune responses were observed in mice after intranasal immunization when ovalbumin was fused to FAI or truncated derivatives. The FAI fragment encompassing the IgG- and fibrinogen-binding regions was the minimal domain exhibiting optimal carrier/adjuvant properties. The obtained results suggest that the FAI protein represents a useful tool to improve the immunogenicity of vaccine antigens. [Copyright &y& Elsevier]

Protective immunity against Streptococcus pyogenes can be induced by intranasal vaccination with the fibronectin-binding domain (H12 fragment) of the fibronectin-binding protein I (SfbI) co-administered with the B subunit of the cholera toxin (CTB) as mucosal adjuvant. However, intranasal administration of A–B moiety bacterial toxins or their derivatives has been associated with potentially severe side effects. Since the SfbI protein exhibits adjuvant properties, we investigated whether vaccination with the H12 fragment alone is sufficient to promote long-lasting protection. The obtained results demonstrated that the humoral and cellular immune responses stimulated at both systemic and mucosal levels were almost identical when mice were vaccinated with the H12 fragment in the presence or absence of CTB. Immunized mice were protected against challenge with a lethal dose of S. pyogenes given 36 or 110 days after primary vaccination to the same extent (80% survival), regardless of CTB incorporation. These results demonstrate that vaccination with the H12 fragment stimulates long-lasting protective immunity. The adjuvant properties exhibited by the fibronectin-binding domain of the SfbI protein strength the potential of this antigen for inclusion in multi-component vaccines against S. pyogenes. [Copyright &y& Elsevier]

Increasing energy autonomy is one of the main reasons for municipalities to invest in renewable energy technologies. In this study, the potential of weather-robust autonomous energy systems is evaluated for 11 003 German municipalities in over one million parallelized techno-economic optimizations utilizing high-performance computing clusters. For this purpose, a holistic municipal-level energy system model (ETHOS.FineRegions) was developed that minimizes annualized system costs in 2045. The completely energy autonomous supply can be established in around 90% of German municipalities corresponding to 50% of the country's population. Especially highly populated municipalities often do not have the capacity to meet their own energy demands due to low wind and open-field PV potentials. Large rooftop PV capacities account for 40% of installed capacity in the autonomous municipalities. Seasonal storage needs are met by large underground thermal storage tanks and batteries provide intraday storage. Furthermore, huge capacity increases are often required for the final 20% of energy demand to be met in order to achieve a degree of autonomy of 100%. The large storage and rooftop PV capacities lead to high specific system costs in the autonomous municipalities with between 144 €/MWh and 174 €/MWh on average, depending on legislation and opposition towards onshore wind installations. By paying a premium of up to 50% compared to the grid-dependent system, 3945 municipalities with 17.2 million inhabitants could become completely autonomous by 2045. For regions that could achieve an autonomous energy supply at moderate costs, however, lost revenues through energy exports could be a decisive argument against autonomy efforts. • Single energy system optimizations for 11003 German municipalities. • Assessment of various scenarios in more than one million techno-economic optimizations. • Utilization of high-performance computing clusters for parallelized optimizations. • Complete energy autonomy technically feasible in 90% of German municipalities. • Extended economic potential for autonomy in 36% of German municipalities. [ABSTRACT FROM AUTHOR]

Abstract: New effective adjuvants are required to improve the performance of subunit vaccines. Here, we showed that bis-(3′,5′)-cyclic dimeric adenosine monophosphate (c-di-AMP), a second messenger molecule in bacteria and archaea, exerts strong adjuvant activities when delivered by mucosal route. In vitro studies showed that c-di-AMP was able to both stimulate pre-activated murine macrophages and promote the activation and maturation of dendritic cells of murine and human origin. Co-administration of c-di-AMP with β-galactosidase (β-Gal) by intranasal route to BALB/c mice resulted in the elicitation of significantly higher serum antigen-specific IgG titres than in controls. The induction of local immune responses was shown by the production of antigen-specific secretory IgA in different mucosal territories. In addition, strong cellular immune responses were observed against both the β-Gal protein and a peptide encompassing its MHC class I-restricted epitope. The ratio of β-Gal-specific antibodies and the secreted cytokine profiles by in vitro re-stimulated splenocytes suggested that a balanced Th1/Th2/Th17 response pattern is promoted by c-di-AMP. When C57BL/6 mice were immunized with OVA and c-di-AMP, vigorous in vivo CTL responses were also observed. These results indicated that c-di-AMP exhibits a high potential as adjuvant for the development of mucosal vaccines, in particular when cellular immunity is needed. [Copyright &y& Elsevier]

Abstract: Here we demonstrated that bis-(3′,5′)-cyclic dimeric inosine monophosphate (c-di-IMP) exhibits potent adjuvant properties. BALB/c or C57BL/6 mice were immunized with the model antigens beta-galactosidase (β-Gal) or Ovalbumin (OVA) alone or co-administered with c-di-IMP by the intranasal route. Animals receiving c-di-IMP showed significantly higher anti-β-Gal or OVA immunoglobulin G titres (IgG) in sera than those vaccinated with β-Gal or OVA alone. Furthermore, strong local immune responses were also detectable in different mucosal territories, as shown by the high levels of β-Gal-specific secretory IgA (sIgA). The analysis of the antigen-specific IgG isotypes in sera, together with the profiles of the cytokines and chemokines secreted by lymphocytes from vaccinated animals showed that the use of c-di-IMP resulted in stimulation of a mixed TH1/TH2/TH17 response. Mucosal immunization of C57BL/6 mice with OVA using c-di-IMP as adjuvant also led to the stimulation of both humoral and cellular (i.e., 60% of antigen-specific lysis by in vivo CTL) responses. Our results demonstrated that the novel compound c-di-IMP exhibits strong adjuvant properties when co-administered with an antigen by the mucosal route, thereby representing a promising candidate adjuvant for the development of mucosal vaccination strategies. [Copyright &y& Elsevier]

Vaccination is the most efficient strategy to protect from infectious diseases and the induction of a protective immune response not only depends on the nature of the antigen, but is also influenced by the vaccination strategy and the co-administration of adjuvants. Therefore, the precise monitoring of adjuvant candidates and their immune modulatory properties is a crucial step in vaccine development. Here, one central aspect is the induction of appropriate humoral and cellular effector mechanisms. In our study we performed a direct comparison of two promising candidates in adjuvant development, the STING activator bis-(3,5)-cyclic dimeric adenosine monophosphate (c-di-AMP) and the Toll-like receptor ligand formulation poly(I:C)/CpG. These were evaluated in C57BL/6 mice using the model antigen ovalbumin (OVA) in subcutaneous vaccination with soluble protein as well as in a dendritic cell (DC) targeting approach (αDEC-OVA). Strikingly, c-di-AMP as compared to poly(I:C)/CpG resulted in significantly higher antigen-specific IgG antibody levels when used in immunization with soluble OVA as well as in antigen targeting to DC. In vaccination with soluble OVA, c-di-AMP induced a significantly stronger CTL, Th1 and IFNγ-producing CD8+ memory T cell response than poly(I:C)/CpG. The response was CTL and Th1 cell dominated, a profile shared by both adjuvants. In the context of targeting OVA to DC, c-di-AMP induced significantly increased Th1 and Th2 cell responses as compared to poly(I:C)/CpG. Interestingly, the Th1 response dominated the overall T cell response only when c-di-AMP was used, indicating a distinct modulatory property of c-di-AMP when the DC targeting immunization approach was exploited. Taken together, we describe superior properties of c-di-AMP as compared to poly(I:C)/CpG in subcutaneous vaccination with soluble antigen as well as antigen targeting to DC. This indicates exceptionally effective adjuvant properties for c-di-AMP and provides compelling evidence of its potential for further adjuvant development, especially also when using DC targeting approaches. [ABSTRACT FROM AUTHOR]

Transfollicular vaccination aims to reach the peri-follicular antigen presenting cells without impairing the stratum corneum (SC) barrier. This would be an optimal vaccination strategy under critical hygienic conditions. Nanoparticles (NPs) are the ideal vehicles for transfollicular delivery of vaccines as they are able to (i) penetrate deeper into the hair follicles than molecules in solution, (ii) can help to stabilize protein based antigen and (iii) improve and modulate the immune response. This study investigates the potential of transfollicular delivery of polymeric NPs using ovalbumin (OVA) as a model antigen. NPs were prepared by a double emulsion method from pharmaceutically well characterized biocompatible and biodegradable polymers poly(lactide-co-glycolide) (PLGA) or chitosan-coated PLGA (Chit-PLGA) using polyvinyl alcohol as stabilizer. The NP formulations are available as freeze dried product which can be re-constituted with water or cell culture medium before use to yield any desired OVA/NP concentration. OVA was protected from cleavage or aggregation inside the NPs and retained its biological activity to 74% (PLGA) and 64% (Chit-PLGA). Thus, when applying a typical dose of 8.5μl/cm2 NP formulation (50mg NPs/ml, 54.3±0.047 and 66.5±0.044μg OVA/mg NPs for PLGA and Chit-PLGA NPs, respectively) an effective dose of 17μg/cm2 (PLGA) or 18μg/cm2 (Chit-PLGA) of active OVA is administered. In a cell culture assay encapsulated OVA stimulated the proliferation of CD4+ (PLGA and Chit-PLGA) and CD8+ T-cells (only Chit-PLGA) to a larger extent than OVA in solution. An adoptive transfer experiment demonstrated that the model antigen OVA can be delivered via the transfollicular route. This preliminary experiment is a proof of concept that by this transfollicular immunization approach it is possible to deliver antigens, thereby stimulating antigen-specific T cells. Both NP formulations improved the delivery efficiency of OVA into the hair follicles on excised pig ears by a factor of 2–3 compared to OVA solution. This delivery efficiency could further be increased by increasing the number of NPs applied per skin area by a factor of ≈2–2.4. Consequently formulation of OVA into PLGA and Chit-PLGA NPs may offer to reduce the dose which needs to be applied for transfollicular immunization. [ABSTRACT FROM AUTHOR]

Abstract: Mucosal vaccine formulations based on purified recombinant C280 γ-Intimin and EspB (Escherichia coli secreted protein B) from enterohaemorragic E. coli co-administered with a pegylated derivative of the TLR2/6 agonist MALP-2 (macrophage-activating lipopeptide) as adjuvant were evaluated in BALB/c mice. After intranasal vaccination, strong humoral and cellular immune responses were observed against C280 γ-Intimin and EspB. Sera of immunized mice inhibit bacterial haemolytic activity in vitro. Antigen-specific T-cell proliferation, IL-4, IL-2 and IFN-γ producing cells, and secretory IgA were mostly detected in animals receiving MALP-2 as adjuvant. These results suggest that C280 γ-Intimin and EspB are good candidate antigens to be incorporated into mucosal vaccines against this important pathogen. [Copyright &y& Elsevier]