Project Number: 1265-32000-083-00
Project Type: Appropriated

Start Date: Nov 07, 2006
End Date: Nov 06, 2011

Objective:
The objectives of the research project plan are as follows: 1) to identify disease resistance genes and immunological responses that influence the course of intramammary infection; 2) to discover and evaluate effective biotherapeutics for the prevention and treatment of bovine mastitis; and 3) to develop strategies that promote cell replacement in the bovine mammary gland.

Approach:
To identify disease resistance genes that influence the course of intramammary infection (Objective 1) we will: 1) compare differential innate immune response patterns and host gene expression profiles that are elicited in response to intramammary pathogens that are readily cleared from the gland versus those that establish chronic infection; 2) determine whether experimentally-induced inflammation enhances clearance of mastitis pathogens that cause chronic subclinical mastitis; and 3) compare the inflammatory and gene expression responses of primiparous versus multiparous cows. To discover and evaluate effective biotherapeutics for the prevention and treatment of bovine mastitis (Objective 2) we will: 1) test the efficacy of intramammary infusion of recombinant bovine sCD14 as a means to recruit neutrophils and promote clearance of E. coli; 2) test the effectiveness of the organic irritant dextran at dry-off to prevent new intramammary infections; 3) evaluate the anti-inflammatory and microbicidal activity of bovine bactericidal-permeability increasing protein (BPI) in various biological fluids as an initial indicator of its utility in the treatment of intramammary and systemic infections; and 4) evaluate the ability of cis-urocanic acid to inhibit neutrophil-induced respiratory burst activity and injury to the mammary epithelium. To identify strategies that promote cell replacement in the bovine mammary gland (Objective 3) we will focus on the biology of bovine mammary stem cells, which are crucial for the proliferation replacement of mammary epithelial cells. In prepubertal heifers, we will: 1) identify mammary stem cells by their ability to retain bromodeoxyuridine label for an extended time and develop genetic markers for these cells, by isolating them from tissue using laser microdissection, and performing microarray analysis to identify markers that distinguish stem cells from non-stem cells; and 2) we will evaluate methods to promote expansion of the stem cell population in vivo by modulating key signaling pathways.