Thermostable Vaccine Compositions and Methods of Preparing Same

Abstract

The disclosure provides compositions relating to thermostable vaccines and methods of preparing same. Specifically, the disclosure provides for methods of preparing thermostable vaccines based on a recombinant ricin neurotoxin protein and uses of co-adjuvants to develop a composition capable of eliciting an immune response in a subject.

Description

GOVERNMENT SUPPORT STATEMENT[0001]This invention was made with government support under grant UO1-A1-08-2210 from the National Institutes of Health. The government has certain rights in the invention.FIELD OF THE INVENTION[0002]The present invention relates generally to the field of dried vaccine compositions. More specifically, to methods of producing dried vaccine compositions bound to adjuvant and containing immunostimulatory molecules.BACKGROUND OF THE INVENTION[0003]Vaccines containing recombinant proteins benefit from or absolutely require an adjuvant to elicit an immune response. (Callahan et al., 1991, The importance of surface charge in the optimization of antigen-adjuvant interactions, Pharm. Res. 8(7):851-858; Singh and O'Hagan 1999, Advances in vaccine adjuvants, Nat Biotechnol 17(11): 1075-81; and O'Hagan et al., 2001, Recent developments in adjuvants for vaccines against infectious diseases, Biomol Eng 18(3): 69-85). Aluminum-salt adjuvants are currently the most widel...

AI Technical Summary

Benefits of technology

The patent describes a method of controlling the particle size in a dried vaccine composition. The method involves combining aluminum salts, a buffer system, a glass-forming agent, and an antigen to create a liquid vaccine formulation. The liquid vaccine formulation is then freezed and lyophilized to create a dried vaccine composition. After reconstitution with an aqueous diluent, the mean particle diameter of the reconstitutable vaccine composition is less than 100 micrometers. The use of certain glass-forming agents, such as trehalose, can help to decrease the particle size. The method can be carried out using tray freezing, shelf freezing, spray-freezing, or shell-freezing. The concentration of the glass-forming agent can be decreased as the cooling rate of the liquid vaccine formulation is increased. Overall, this method can help to create a more stable and effective vaccine composition.

Problems solved by technology

Nonetheless, there are significant limitations in the use of aluminum-salt adjuvants in many subunit vaccines based on recombinant proteins, peptides, and chemically synthesized vaccines.

These limitations include the general aspects of vaccine storage and stability, since vaccine containing aluminum adjuvants can be stored only within narrow temperature ranges, and cannot be frozen.

Further limitations include the generally accepted view that aluminum adjuvants are relatively weak, do not foster the development of cellular immunity, and may favor the development of antibodies that are non-neutralizing in cases where neutralizing antibodies are necessary to block viral infections or impede the activity of biological toxins.

However, when vaccines formulated with aluminum-salt adjuvants are processed in an attempt to improve stability through freezing and lyophilization, a loss of potency occurs, where potency is a summation of the quality of the vaccine measurable by a series of tests that can include immunogenicity in animals, chemical degradation of protein antigen, denaturation of protein antigen, or loss of substituent immunogenic epitopes.

Loss of potency is associated with loss of efficacy in humans.

Previous studies have suggested that a freeze-dried vaccine product containing adjuvant cannot be produced due to aggregation of the adjuvant particles.

Particle aggregation may account for significant losses.

However, a solution pH that provides optimal protein stability, may not allow for appropriate binding of the vaccine to adjuvants.

Very little data is available on the storage of dried vaccines under elevated temperature conditions, as most of the attempts to generate dried vaccines have been to obtain inhalable powders or preparations able to survive moderate excursions in temperature.

Although a moderate amount of stability can be achieved with liquid suspension vaccines, it is not likely that all stability parameters can be met for longer storage periods that are required for vaccines to be stockpiled and distributed.

In the case of protein immunogens that are adsorbed to aluminum adjuvants crystals, the measurement of function and other parameters in vitro is correspondingly more difficult, since protein may be sequestered and difficult to remove for analysis.

Thus, function can only be tested by immunogenicity and protection studies.

These studies demonstrated the difficulty in identifying a pre-lyophilization solution pH that confers adequate physical and chemical stability to the proteins studied during lyophilization and storage.

Protein aggregation was minimized following lyophilization from a solution at pH greater than 6, although, deamidation occurred at an unacceptably high rate.

However, Roser et al., while disclosing prevention of gross particle aggregation, do not disclose the importance of freezing rate of a particulate suspension or other factors critical to control and maintain pre-lyophilization particle size and protein structure in an aluminum-salts containing vaccine in the presence of trehalose.

However, a variety of exploratory formulations to enhance vaccines have been developed as more potent alternative to aluminum-salts adjuvants, but are not currently available in FDA-licensed human vaccines.

However the toxoid is considered to be too toxic for routine use in humans and dgRTA is difficult and expensive to produce, and also retains both active sites and could induce toxic side effects in humans.

Although ricin A chain is at least 1000-fold less toxic than the native ricin, it still retains enzymatic activity that may result in toxicity when used as a vaccine (Thorpe, Detre et al., 1985, Modification of the carbohydrate in ricin with metaperiodate-cyanoborohydride mixtures.

These proteins are nontoxic individually, but when administered together are a potent toxin, causing rapid cell death.

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