Currently, the serological diagnosis of Lyme disease is complicated by cross-reactivity with other microbes, including disease agents. A 41 kDa flagellar protein (flagellin) of Borrelia burgdorferi has been shown to be both an immunodominant antigen, IgM against this antigen rising early during infection, and to possess epitopes that are unique to the genus Borrelia. The nucleic acid sequence of flagellin is known. The intent of these studies will be to synthesize six to ten-mere overlapping oligopeptides covering the entire sequence, screen these putative oligopeptide antigens and then against disease state sera. Phase Ii studies will consist of evaluating prototype ELISA and DIA in large scale clinical trials to more carefully define the sensitivity of the assays. Phase II studies will also include amino acid substitution experiments to optimize both antigen affinity and specificity.