Whole-Inactivated Influenza Virus Is a Potent Adjuvant for Influenza Peptides Containing CD8+ T Cell Epitopes

Influenza peptide antigens coding for conserved T cell epitopes have the capacity to induce cross-protective influenza-specific immunity. Short peptide antigens used as a vaccine, however, often show poor immunogenicity. In this study, we demonstrate that whole-inactivated influenza virus (WIV) acts as an adjuvant for influenza peptide antigens, as shown by the induction of peptide-specific CD8+ T cells in HLA-A2.1 transgenic mice upon vaccination with the influenza-M1-derived GILGFVFTL peptide (GIL), formulated with WIV. By screening various concentrations of GIL and WIV, we found that both components contributed to the GIL-specific T cell response. Whereas co-localization of the peptide antigen and WIV adjuvant was found to be important, neither physical association between peptide and WIV nor fusogenic activity of WIV were relevant for the adjuvant effect of WIV. We furthermore show that WIV may adjuvate T cell responses to a variety of peptides, using pools of either conserved wild-type influenza peptides or chemically altered peptide ligands. This study shows the potential of WIV as an adjuvant for influenza peptides. The simple formulation process and the solid safety record of WIV make this an attractive adjuvant for T cell peptides, and may also be used for non-influenza antigens

The effect of formulation on spray dried Sabin inactivated polio vaccine

The objective of this study was to develop a stable spray dried formulation, containing the three serotypes of Sabin inactivated polio vaccine (sIPV), aiming for minimal loss of native conformation (D-antigen) during drying and subsequent storage. The influence of atomization and drying stress during spray drying on trivalent sIPV was investigated. This was followed by excipient screening, in which monovalent sIPV was formulated and spray dried. Excipient combinations and concentrations were tailored to maximize both the antigen recovery of respective sIPV serotypes after spray drying and storage (T = 40 °C and t = 7 days). Furthermore, a fractional factorial design was developed around the most promising formulations to elucidate the contribution of each excipient in stabilizing D-antigen during drying. Serotype 1 and 2 could be dried with 98% and 97% recovery, respectively. When subsequently stored at 40 °C for 7 days, the D-antigenicity of serotype 1 was fully retained. For serotype 2 the D-antigenicity dropped to 71%. Serotype 3 was more challenging to stabilize and a recovery of 56% was attained after drying, followed by a further loss of 37% after storage at 40 °C for 7 days. Further studies using a design of experiments approach demonstrated that trehalose/monosodium glutamate and maltodextrin/arginine combinations were crucial for stabilizing serotype 1 and 2, respectively. For sIPV serotype 3, the best formulation contained Medium199, glutathione and maltodextrin. For the trivalent vaccine it is therefore probably necessary to spray dry the different serotypes separately and mix the dry powders afterwards to obtain the trivalent vaccine.</p

mRNA-lipid nanoparticle COVID-19 vaccines : structure and stability

A drawback of the current mRNA-lipid nanoparticle (LNP) COVID-19 vaccines is that they have to be stored at (ultra)low temperatures. Understanding the root cause of the instability of these vaccines may help to rationally improve mRNA-LNP product stability and thereby ease the temperature conditions for storage. In this review we discuss proposed structures of mRNA-LNPs, factors that impact mRNA-LNP stability and strategies to optimize mRNA-LNP product stability. Analysis of mRNA-LNP structures reveals that mRNA, the ionizable cationic lipid and water are present in the LNP core. The neutral helper lipids are mainly positioned in the outer, encapsulating, wall. mRNA hydrolysis is the determining factor for mRNA-LNP instability. It is currently unclear how water in the LNP core interacts with the mRNA and to what extent the degradation prone sites of mRNA are protected through a coat of ionizable cationic lipids. To improve the stability of mRNA-LNP vaccines, optimization of the mRNA nucleotide composition should be prioritized. Secondly, a better understanding of the milieu the mRNA is exposed to in the core of LNPs may help to rationalize adjustments to the LNP structure to preserve mRNA integrity. Moreover, drying techniques, such as lyophilization, are promising options still to be explored

Buccal and sublingual vaccine delivery

Drug Delivery Technolog

Hyaluronan molecular weight: effects on dissolution time of dissolving microneedles in the skin and on immunogenicity of antigen

Biomaterials used as matrix for dissolving microneedles (dMNs) may affect the manufacturing process as well as the potency of the active pharmaceutical ingredient, e.g. the immunogenicity of incorporated vaccine antigens. The aim of this study was to investigate the effect of the molecular weight of hyaluronan, a polymer widely used in the fabrication of dMNs, ranging in molecular weight from 4.8 kDa to 1.8 MDa, on the dissolution of microneedles in the skin in time as well as the antibody response in mice and T-cell activation in vitro. Hyaluronan molecular weight (HA-MWs) did not affect antibody responses (when lower than 150 kDa) nor CD4+ T-cell responses against model antigen ovalbumin. However, the HA-MWs had an effect on the fabrication of dMNs. The 1.8 MDa HA was not suitable for the fabrication of dMNs. Similarly, the 4.8 kDa HA generated dMN arrays less robust compared to the other HA-MWs requiring optimization of the drying conditions. Finally, higher HA-MWs led to longer application time of dMN arrays for a complete dissolution of microneedles into the skin. Specifically, we identified 20 kDa HA as the optimal HA-MW for the fabrication of dMNs as with this MW the dMNs are robust and dissolve fast in the skin without affecting immunogenicity

Developments in the formulation and delivery of spray dried vaccines

Spray drying is a promising method for the stabilization of vaccines, which are usually formulated as liquids. Usually, vaccine stability is improved by spray drying in the presence of a range of excipients. Unlike freeze drying, there is no freezing step involved, thus the damage related to this step is avoided. The edge of spray drying resides in its ability for particles to be engineered to desired requirements, which can be used in various vaccine delivery methods and routes. Although several spray dried vaccines have shown encouraging preclinical results, the number of vaccines that have been tested in clinical trials is limited, indicating a relatively new area of vaccine stabilization and delivery. This article reviews the current status of spray dried vaccine formulations and delivery methods. In particular it discusses the impact of process stresses on vaccine integrity, the application of excipients in spray drying of vaccines, process and formulation optimization strategies based on Design of Experiment approaches as well as opportunities for future application of spray dried vaccine powders for vaccine delivery

DEVELOPMENT OF INACTIVATED POLIO VACCINE FROM ATTENUATED SABIN STRAINS FOR CLINICAL STUDIES AND TECHNOLOGY-TRANSFER PURPOSES

Recently, responding to WHO’s call for new polio vaccines, the development of Sabin-IPV (injectable, formalin-Inactivated Polio Vaccine, based on attenuated ‘Sabin’ polio virus strains) was initated at NVI. This activity plays an important role in the WHO polio eradication strategy. The use of Sabin instead of wild-type Salk polio strains will provide additional safety during vaccine production. Initially, the Sabin-IPV production process will be based on the scale-down model of the current, and well-established, Salk-IPV process. In parallel, process development, optimization and formulation research is being carried out to further modernize the process and reduce cost per dose. The lab-scale accelerated process development, product characterization, clinical lot production, and preparations for technology transfer will be discussed. Multivariate data analysis (MVDA) was applied on data from current IPV production (more than 60 Vero cell culture based runs) to extract relevant information, like operating ranges. Subsequently, based on the MVDA analysis, a 3-L scale-down model of the current twin 750-L bioreactors has been setup. Currently, in this lab-scale process, cell and virus culture approximate the large-scale and process improvement studies are in progress. This includes the application of increased cell densities, animal component free media, and DOE optimization in multiple parallel bioreactors. Also, results will be shown from large-scale (to prepare for future technology transfer) generation and testing of Master- and Working virus seedlots, and clinical lot (for phase I studies) production under cGMP conditions. The obtained product was used for immunogenicity studies in rats. It was shown that Sabin-IPV induces a good immune response, and a comparison will be made to regular Salk-IPV. Finally, technology transfer to vaccine manufacturers in low and middle–income countries will take place. For that, an international Sabin-IPV manufacturing course, including practical training at pilot-scale, is being setup