Vaccine products containing recombinant antigens must include an adjuvant to aid in the potentiation of the immune response. The only adjuvants currently appearing in FDA-approved products are the aluminum-salt adjuvants aluminum hydroxide and aluminum phosphate. A lyophilized vaccine product would be highly beneficial due to the improved stability of dried formulations. However, there is some concern that the lyophilization of such products results in a loss in potency of the vaccine due to aggregation of the adjuvants. The main goal of this dissertation is to examine the causes of aggregation of aluminum salt adjuvants and examine how changes in the physical and chemical properties of lyophilized vaccines affect the immunogenicity and storage stability of such vaccines.

We investigated the aggregation of aluminum hydroxide adjuvants during freezing and drying in succinate buffer and found adjuvant aggregation to be related to freeze-concentration-induced buffer ion crystallization and surface charge modification. Aggregation of adjuvant particles during freezing and drying was minimized through the use of suitable concentrations of a glass-forming excipient and/or faster cooling methods during freezing.

Two model vaccines were then tested for their ability to elicit antibody production. The immunogenicity of freeze/thaw and lyophilized lysozyme vaccines containing either aluminum hydroxide or aluminum phosphate adjuvant was independent on the adjuvant particle diameter and the fraction of protein bound to adjuvant, both of which were previously-hypothesized to be critical factors dictating immunogenicity. The immunogenicity of freeze-dried and spray freeze-dried alkaline phosphatase vaccines was also investigated and found to be independent on the particle diameter and retained antigen activity.

Finally, the stability of lyophilized preparations of a vaccine containing an antigen being developed for a multivalent vaccine against botulism was investigated. The stability of the vaccine was found to be improved compared to liquid formulations of the same antigen. While there were changes in strength of binding of the antigen to the adjuvant and some alterations in the mass spectroscopy analysis of the digested antigen, these did not negatively affect the immunogenicity of the dried vaccines during storage. The spray freeze-dried vaccine had statistically equivalent potency as a liquid vaccine preparation at up to fifteen weeks of storage.