The goal of this project is to develop a method to prevent staphylococcal mastitis in dairy cows (both new infections and relapses) by treatment with modified (detoxified) staphylococcal enterotoxins. The detoxified agent will be administered and tested alone and with other antigens as an adjuvant. The goals of the Phase I project are: 1) to confirm preliminary data indicating that detoxified enterotoxin acts as an immunostimulant, capable of preventing periparturient depression of the immune responses, and 2) to determine that detoxified enterotoxin does not induce aberrant immune responses characteristic of native toxin.The project will use a modified staphylococcal enterotoxin C to induce non-specific stimulation of the bovine immune system, resulting in a heightened immune response to both enterotoxigenic and non- enterotoxigenic strains of Staphylococcus aureus. Preliminary evidence has indicated that this compound invigorated bovine immune responses to increase resistance to experimental intramammary infection with S. aureus. It is expected that this novel approach to immunization against S. aureus, by using detoxified enterotoxins as immune stimulants, will circumvent difficulties associated with previous vaccination attempts centered on selected virulence factors that did not lead to a broad spectrum of protection.
Anticipated Results/Potential Commercial Applications of Research::We will establish that detoxified enterotoxin, acting as an attenuated superantigen, can be safely administered to cows to effect a general immunostimulation. Mastitis is the most costly livestock disease. It is estimated that losses due to mastitis exceed $billion per annum. Clearly the development of an effective treatment to reduce the impact of mastitis would have a positive impact on the national dairy industry and represent a valuable commercial product. The development, through immune enhancement, of an effective immunostimulant to prevent mastitis would represent one of very few prophylactic treatments.
