A major discovery of inflammatory bowel disease (IBD) research in the past decade has been the elucidation of bacteria as necessary for disease pathogenesis. However, no particularly bacterial species, or antigen have been identified. In ulcerative colitis (UC) marker antibodies against neutrophil components (pANCA) have been identified in 68-85 percent of patients. With only 6 percent of the other idiopathic IBD, Crohn's disease (CD) scoring positive for pANCA, this represents specific diagnostic tool. Using a monoclonal anti-neutrophil antibody (5-3 antibody), they have identified two novel antigens implicated in IBD pathogenesis. Both the E. coli OmpC protein and the Mycobacterium Tb, HupB proteins are recognized by 5-3 antibody. The goal of this project is to develop and optimize ELISAs based on these proteins. Satisfaction of Phase I of this proposal will establish novel diagnostics for this disease, and represent the first stage of evaluation of these targets for design of a therapeutic regimen.