Probing Stability of Lyophilized Vaccine Against Bovine Mastitis

Staphylococcus aureus is a leading cause of mastitis, or infections in the udder, in dairy cows. Mastitis causes significant financial losses and with the rapid increase of antibiotic resistant bacteria, such as Methicillin-resistant Staphylococcus aureus (MRSA), it is vital to create alternative ways to fight these pathogens. Our lab is developing and testing a mucosal chimeric vaccine against bovine mastitis containing two surface antigens from S. aureus. The genes for the adhesins isdA and clfA were cloned with those for Vibrio cholerae cholera toxin A2/B (CTA2/B) to create the intranasally administered vaccine. The purification of this vaccine was scaled up using 1L culture volumes and D-galactose agarose affinity purification. Purified proteins were analyzed by SDS-PAGE and bicinchoninic (BCA) assay. Currently we have produced over 15 mg of vaccine for use in future bovine vaccine challenge studies. Lyophilization is a well-recognized method in the pharmaceutical industry used to store biologically active drugs that are not stable in solution, or to prolong the shelf-lives of drugs. Excipients can have a great influence on performance and stability of lyophilized drugs. IsdA chimera was lyophilized using a variety of excipients and stored at different temperatures. The stability was analyzed using SDS-PAGE and BCA assay