Academic literature on the topic 'Accelerating vaccine formulation development'

Many vaccines require an adjuvant to induce a strong immune response. Aluminum–containing adjuvants have been approved by the United States Food and Drug Administration for human use for many years. There are two main aluminum-containing adjuvants, aluminum hydroxide and aluminum phosphate. Due to their favorable safety profile, aluminum-containing adjuvants have been widely used in human vaccines for decades. Many currently licensed and commercially available vaccines contain aluminum-containing adjuvants. However, aluminum-containing vaccine adjuvants suffer from two major limiting factors: (1) aluminum-containing adjuvants can only weakly or moderately potentiate antigen-specific antibody responses and are generally considered incapable of inducing cellular immune responses; (2) vaccines that contain aluminum-containing adjuvants require cold-chain refrigeration for storage and distribution, and may not be frozen, because freezing of the vaccine in dispersion causes irreversible coagulation that damages vaccines (e.g., loss in potency and stability). In this dissertation, the first limitation was addressed by reducing the size of the aluminum hydroxide from micrometers (3-10 micrometer) to nanometers of less than 200 nm, and the second limitation mentioned above was addressed by freeze-drying vaccines that contain aluminum salts as adjuvants into a dry powder using thin-film freeze-drying. In addition, using an improved experimental design, the vaccine adjuvant activities of nanoparticles of around 200 nm was compared to that of the nanoparticles of around 700 nm. The smaller 200 nm nanoparticles showed a more potent adjuvant activity than the larger nanoparticles. When dispersed in an aqueous medium, both aluminum hydroxide and aluminum phosphate are physically 1–20 micrometer particulates. There are data showing that particulate vaccine carriers of around 200 nm (or less) may be optimal in potentiating the immunogenicity of vaccines. Based on this finding, aluminum hydroxide nanoparticles of 112 nm were synthesized, and its adjuvant activity was compared to that of the traditional aluminum hydroxide adjuvant, which have particulates of 3-20 micrometer. Using ovalbumin and Bacillus anthracis protective antigen protein as model antigens, it was found that protein antigens adsorbed on the aluminum hydroxide nanoparticles induced stronger antigen-specific antibody responses than the same protein antigens adsorbed on the traditional aluminum hydroxide microparticles of around 9.3 µm. Importantly, the inflammation reactions induced by aluminum hydroxide nanoparticles in the injection sites were milder than that induced by microparticles. Simply reducing the particle size of the traditional aluminum hydroxide adjuvant in suspension from micrometers into nanometers represents a novel and effective approach to improve its potency. The second limitation was addressed by converting vaccines that contain an aluminum salt as an adjuvant from an aqueous dispersion into a dried powder using thin-film freeze-drying. There is evidence that aluminum-containing vaccines can be lyophilized to dry powders using high speed freezing methods. Thin-film freezing is a high speed freezing method with a freezing rate between 100 to 10,000 K/s, but the feasibility of using thin-film freeze-drying to freeze-dry vaccines that contain aluminum salts as adjuvants has not been tested before. In this dissertation, Using ovalbumin as a model protein antigen and aluminum hydroxide or aluminum phosphate as an adjuvant, it was confirmed that vaccines that are adjuvanted with aluminum hydroxide or aluminum phosphate can be freeze-dried with as low as 2% (w/v) of trehalose as a cryoprotectant by thin-film freeze-drying without causing vaccine aggregation while preserving the immunogenicity of the vaccine. Finally, the feasibility of using the thin-film freeze-drying method to freeze-drying vaccines that contain aluminum salts as adjuvants was further confirmed by drying a commercial aluminum salt-adjuvanted tetanus toxoid vaccine. Vaccines that contain aluminum salts as adjuvants may be converted to a dry powder using the thin-film freeze-drying method to avoid loss of potency due exposure to freezing conditions during transport and storage.<br>text

Dissertação de mestrado em Biophysics of Bionanosystems<br>The main goal of this work was to characterize and explore the potential of Dioctadecyldimethylammonium Chloride (DODAC) / Monoolein (MO) liposomes in a 1:2 proportion and identify the formulations that could be used in the development of an immunoprotective protocol for Chronic Myeloid Leukemia (CML). CML has long been recognized as one of the most responsive leukemic disorder to immunotherapy. CML is potent model for immune therapy in humans because there is a specific gene rearrangement, BCR/ABL, which product, P210bcr/abl, can be the target antigen. The loading of drugs into particles at the nanometer size range is a recognized technique for the optimization of controlled drug delivery. In its use in vaccines, liposomes have the advantage of being able to maintain antigens present in the organism for long enough to obtain an immune response. Different methods of preparation and distinct peptide/lipid molar ratios were used to prepare P210bcr/abl / DODAC:MO (1:2) nanoparticles. This thesis describes results for biophysical characterization of the peptide/lipid system, encapsulation efficiency and exposure of THP-1 cells to the nanoparticles. The lipid content was essential to achieve the desired nanoparticles. The highest lipid concentration showed higher encapsulation, however, a lower lipid content induced a more efficient cell response. The peptide/lipid system was capable of inducing a stronger cell response than the peptide by itself, emphasizing the potential of this system in vaccine development for the treatment of CML.<br>O objetivo principal deste trabalho foi caracterizar e explorar o potencial dos lipossomas de cloreto de Dioctadecildimetilamónio (DODAC) / Monooleina (MO) numa proporção de 1:2 e identificar as formulações que poderão ser usadas no desenvolvimento de um tratamento imunoprotetor para a Leucemia Mieloide Crónica (LMC). A LMC é desde há muito tempo conhecida como uma das desordens imunológicas mais responsivas à imunoterapia. A LMC é um poderoso modelo para imunoterapia em humanos devido à existência de um gene específico BCR/ABL, cujo produto, P210bcr/abl, pode ser usado como antigene-alvo. A incorporação de fármacos em partículas a uma escala nanométrica é uma técnica reconhecida para a optimização da entrega controlada de fármacos. No seu uso em vacinas, os lipossomas possuem a vantagem de ser capazes de manter os antigenes presentes no organismo o tempo suficiente para se obter uma resposta imune. Diferentes métodos de preparação e várias razões molares de péptido/lipido foram usadas para preparar nanoparticulas de P210bcr/abl / DODAC:MO(1:2). Esta tese descreve os resultados obtidos da caracterização biofísica do sistema péptido/lípido, eficiência de encapsulação e exposição das células THP-1 às nanopartículas. O conteúdo lipídico foi essencial para obter nanopartículas desejáveis. A concentração mais alta de lípido demonstrou maior eficiência de encapsulação, no entanto, uma concentração de lipído mais baixa mostrou-se mais eficiente em induzir uma resposta por parte das células. O sistema péptido/lipido foi capaz de induzir uma resposta mais forte do que o pétido por si só, enfatizando o seu potencial no desenvolvimento de uma vacina para o tratamento da LMC.

This dissertation describes two different projects. The first is the development of an oral DNA vaccine delivery system for fish. A novel oral DNA vaccine delivery system was developed for Rainbow Trout by combining non-viral vectors (polycationic liposomes or polycationic polymer) to facilitate the DNA vaccine's uptake by cell membranes along with enteric-coated protection of the DNA embedded in microparticles to prevent DNA degradation in the gastrointestinal tract. Spray drying and spray coating bead techniques were employed in the preparation of the DNA vaccine microparticles. The spray drying technique allowed production of spherical shape enteric-coated microparticles with a particle size range of 0.18 to 20 ��m. Larger particle sizes of 40-50 mesh were obtained from the spray-coated bead technique. The resultant DNA vaccine microparticles were granulated with regular fish feed and given to fish to investigate the efficacy of the delivery system in providing protection against IHNV, and to demonstrate the ease of administration in fish. An in vivo fish trial experiment showed improvement in fish survival rate when fish were immunized with larger particle size DNA vaccine microparticles. Further research to find effective vector carriers for the DNA vaccine delivery system and to seek modifications of the delivery system that will still prevent the denaturation of plasmid DNA that will also facilitate membrane uptake of the DNA vaccine is needed in order to develop a safe, effective, and commercially viable vaccine to control the outbreak of IHNV. The second project of the dissertation is prediction of in vitro drug release profiles from a novel matrix tablet spray-coated with a barrier membrane using mathematical and statistical models. Tablets were prepared by direct compression followed by spray coating. The relationship of the amount of hydrophilic materials in the core tablets and barrier thickness on drug release mechanism was investigated using factorial design and regression analysis. Drug release characteristics were influenced and can be controlled by modifying the amount of hydrophilic materials in the core tablet and the barrier thickness. Mathematical equation generated from regression analysis of n-value, lag time, and percent drug release as a function of the amount of hydrophilic material and the amount of coating material applied can now be used as a tool for predicting and optimizing in vitro drug release from matrix tablets spray-coated with a barrier membrane.<br>Graduation date: 2003