AN INTRAMAMMARY SUBUNIT VACCINE TO PREVENT STAPHYLOCOCCUS AUREUS BOVINE MASTITIS

Our long term goal is to produce a cost-effective vaccine to eliminate S. aureus mastitis in dairy cows. We hypothesize that the CTA2/B vaccine platform can be adapted to incorporate additional targeted S. aureus antigens, and that this platform canbe delivered safely to to the bovine udder to induce specific immuntiy. To test our hypothesis and support the long-term goal of developing a vaccine to reduce or eliminate S. aureus mastitis in dairy cows, we propose the following two technical objectives:Objective 1: Construct a rationally designed multivalent vaccine to prevent clinical and subclinical S. aureus mastitis by incorporating additional targeted antigens. A need remains to expand vaccine protection by incorporating additional antigens from multiple virulence pathways. To address this need, we will build upon previous omics studies to prioritize candidates and expand the current CTA2/B vaccine. We will score a pool of antigens in silico based upon: 1) vaccine antigen prediction, 2) immunoinformatics and epitope prediction, and 3) genomic antigen conservation. Up to ten final candidates will be cloned for chimera expression, using original and newly constructed CTA2/B vectors. Resulting chimeras will be purified, assessed for stability and binding and combined into a new multivalent vaccine.Objective 2: Determine vaccine safety and efficacy after intramammary vaccination in a pilot bovine challenge trial. Intramammary vaccination has been successful in bovine trials, however the safety and efficacy of this route using enterotoxin-based adjuvants is unknown. To address this question, we will perform a randomized/blinded challenge trial using six cows vaccinated and boosted through the intramammary route during milking. Milk and serum will be collected for cytokine, antigen-specific antibody and T-cell proliferation assay. Clinical outcomes and bacterial shedding will be used to assess vaccine efficacy.